Head Space???

PolarFBear · February 8, 2021, 07:26 PM

I've heard this phrase "head space". What EXACTLY is it and how do you measure it? I'm working on a .303 British of 1956 vintage. My brass is not lasting very long, three reloads at minimum levels. Thanks.

std7mag · February 8, 2021, 08:00 PM

In your case, the 303 British, the head space will be measured from the bolt face, to a datum point on the shoulder of the chamber.
As far as the cartridge goes, will be the base to a datum on the shoulder of the cartridge.
You can get the information from CIP, as it's a European based cartridge.

Nodak1858 · February 8, 2021, 09:51 PM

Doesn't the 303 headspace on the rim?

rc · February 8, 2021, 09:52 PM

So the most basic definition of head space is the space between your ears

On a more serious note, it is the movement front to back that a cartridge has to move in the chamber of a gun when the cylinder, bolt or slide is closed. Some cartridges control headspace on the rim. So a revolver head space is the amount of room the cartridge in the firing position has to slop back and forth in the chamber against the breech face of the revolver and the shoulder on the chamber. Some cylinders have recessed faces and others don't. In auto pistols that headspaced on the rim like 38 auto that was once the space between the back of the barrel chamber and the breech face. Same is true for many rimmed caliber cartridges. However, it was found that setting head space on the mouth of the case leads to more accurate hand guns. So head space for 9mm or modern 38 super as an example is the amount of extra space between the chamber mouth leading to the barrel and the end of the hood which will determine how far forward the slide can go relative to the cartridge. Usually it is minimal. If bullets are not seated deeply enough and bind against the rifling the case will stick up above the barrel hood and the cartridge won't chamber due to insufficient head space for the slide or bolt to close.

In bottle neck centerfire rifles the distance between the breech face and the tapered portion of the chamber set head space. Every time you shoot something like a 223 the shoulder bumps forward. Resizing dies bump the case back so it will chamber smoothly in any gun of that chambering. That difference is basically the head space. Neck sizing only sizes the neck to accept a bullet tightly so the head space it technically zero because you are not bumping back the case to standard factory spec.

HiBC · February 8, 2021, 10:17 PM

Here we go again!!
I suggest you use the search function.You can read for hours what we have already written.
Too many people have their own ideas.
1) The flat face with the primer pocket in it is the case head.When the cartridge if fully chambered,the case head's rearward travel is limited by the breech face.

2) The firearm chamber will have a feature to limit and stop the forward movement of the cartridge. This may be a RIM, (example :30-30 Winchester) may be a BELT(example: 375 H+H) It might be the CASE MOUTH (example 45 ACP) or it might be the SHOULDER of a rimless bottleneck case.

I'll leave the discussion of "Datum" for an advanced class.At this point,its distracting.

3) HEADSPACE is the distance from the breech face to the feature in the chamber designated to stop or limit the forward travel of the cartridge.
Thats it.

4) For us to be able to have a Remington and a Winchester and a Colt,and various ammo manufacturers,some standards were necessary. In the USA,the org that keeps the standards s SAAMI

Per SAAMI standards,there are HEADSPACE GAUGES that are used to check the chamber depth is to standard. The "Go" and"No Go" gauge are used to properly chamber and check a newly manufactured gun. A "Field Gauge" is more generous.It is used to determine a worn gun should be taken out of service

5) Note "Headspace" is only about the firearm. All things "headspace" can be established and checked with not one cartridge within 500 miles.

6) The term "Head Clearance" applies to the clearance between the breech face and the case head when the cartridge is traveled forward to stop against the headspace feature of the chamber. Ammunition tolerances and reloading practices are part of head clearance.

7) Number of reloads only matters to those who reload. Those who reload can learn to control head clearance to get more reloads.
303 Brit headspaces on the rim. To do that, the dies size the shoulder to provide clearance at the shoulder. The shoulder defers to the rim. The handloader can say "No" to that. The handloader can adjust the dies to not size the shoulder so much. Then the shoulder is the dominant headspace feature You can control that.

In a later post,I can tell you how I do it. Its not the only way

Bart B. · February 8, 2021, 10:47 PM

Raise your die a few thousandths in the press then resize a fired case to see if it chambers easy.

RC & std7mag, note the bold text.....

From SAAMI glossary......

HEAD CLEARANCE
The distance between the head of a fully seated cartridge or shell and the face of the breech bolt when the action is in the closed position. Commonly confused with headspace.

HEADSPACE
The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats. 1. BELT: A type of chamber design in which the cartridge seats in the chamber on an enlarged band ahead of the extractor groove of the cartridge body. 2. MOUTH: A type of chamber design in which the cartridge seats in the chamber on the mouth of the cartridge case. 3. RIMLESS: A type of chamber design in which the cartridge seats in the chamber on the shoulder of the cartridge case. 4. RIMMED: A type of chamber design in which the cartridge seats in the chamber on the rim or flange of the cartridge case.

RC20 · February 8, 2021, 11:15 PM

The OPS issue is not arguing the techy definition of headspace but what to do about a 3 case life limit.

Ergo, the 303 has a lot of clearance in the chamber over a sized case as its a battle rifle intended to be in the mud, swamps and sand and you name it. Lot of experience behind it in that regard.

And they could care less about brass life, they don't use it but once (we do of course)

So, the real issue is can you do something about it?

The answer is probably but you have to work at it.

First you need to get the Hornady device that goes on the shoulder, a micrometer to measure and then you have to fiddle with your dies to move the shoulder back about .003 and no more.

That stops the crunch down and then re-stretch of brass you are experiencing.

Another part of that is figuring out if your 303 has the right bolt face to minimize the case movement.

All the nitty gritty tech details aside, the rim on a 303 is the basis of reality. Ergo you can minimize how hard the brass works.

But, in a 303, you also have that space between the head and the rim that a rebate rim per the 06 does not have.

You don't want excess there either. I believe they had like 4 different bolt heads for the 303.

I am not familiar with the process but that can be looked up.

Bart B. · February 8, 2021, 11:33 PM

Quote:

Originally Posted by RC20

The OPS issue is not arguing the techy definition of headspace but what to do about a 3 case
But, in a 303, you also have that space between the head and the rim that a rebate rim per the 06 does not have.

30-06 case heads are not held against the bolt face when fired.

Nor is it a rebated rim case.

HiBC · February 8, 2021, 11:44 PM

Quote:

The OPS issue is not arguing the techy definition of headspace but what to do about a 3 case life limit.

No,read the OP again. The OP asked "Exactly what is headspace"

Which is an excellent question,and a perfect starting place to learn how to improve case life.

Once we agree on terms,we can avoid a lot of long,difficult trips off into the swamp of misinformation.

Colorado Redneck · February 9, 2021, 12:13 AM

PolarFBear, what is rendering the brass unusable? Split case at the mouth? Case head separation?

HiBC · February 9, 2021, 12:38 AM

While this is not the method I use,looking at the product will help you see what needs to be measured,and one workable approach.
https://www.hornady.com/headspace-bushings#!/

Unclenick has described getting a hardware store aluminum bushing and resting it on the case shoulder. You might try a .375 hole.

The first firing.the cartridge case is fireformed to your chamber. BEFORE you run it into the sizing die,these tools will give you a reference measurement of you case head to shoulder . Its just a measurement to a base line starting point.Once you have a starting point,you can measure change.

If you have feeler gages,you can use those between the die and shellholder.

Try a .015 or a .020 to start. You backed the die off that much. Lube and size a case,after you write down that base line fire formed length.

Bring the die down .005 at a time,using the feeler gages. Measure the case each time till you get a change. Now,I should tell you the length might grow initially. Make note of when you start to shorten the case head to shoulder dimension. Lets say your original base line measurement was zero head clearance

I have no SMLE experience. I don;t know how much head clearance they require. Try .003. I've heard about the rear lugs .etc.

I try to set my modern bolt rifle ammo at .002 head clearance.

You can probably take it from here

Nathan · February 9, 2021, 06:04 AM

First, what is causing your short case life? I’m assuming it is case head separations??

As you can see, this is a rimmed case. You need a 303 British field gauge to confirm the rifle is in spec. LINK PTG also has them. The PTG might be a better choice as Forster has a reputation for being overly precise. A field gauge is a no go gauge for rifles that have been shot.

The fix if the rifle gauges ok is all in your fireforming of new brass. If you buy new brass and expand the neck to 0.338”, then fl size until it barely fits in the chamber. This false shoulder will blow out the shoulder without moving the brass near the head. Then FL size to only push the shoulder back 0.002” with successive loadings.

eflyguy · February 9, 2021, 06:41 AM

I don't reload, so I'm probably too ignorant to know better, but it strikes me as slightly concerning that someone who reloads - especially a less-than-popular cartridge - doesn't know what headspace is.

PolarFBear · February 9, 2021, 09:36 AM

Nathan and ColoradoRedneck- case head separation. "eflyguy", I take great pains on visual inspection of my brass. I suggest you endeavor to learn, or at least try, a hobby before you offer castigation. Walk in "our" shoes. For all replies, THANKS. My only real experience in "head space" issues was an incident of case head separation in a 50 BMG, waaaaay back in my youth. Caught some brass in "near vital" areas. I load this .303 for my son and want to maximize safety. Didn't realize it was SUCH a touchy issue.

HiBC · February 9, 2021, 09:43 AM

He is asking the right questions in the right place. We all start somewhere.

Ask the question "What is headspace?" and you CAN get a maddening amount of dis-information.

Bart B. · February 9, 2021, 09:52 AM

Both Redding and Hornady define headspace as the space between the case head and breech face when the case is fully forward in the chamber.

https://www.redding-reloading.com/te...with-headspace

https://www.hornady.com/team-hornady...nal-ballistics

HiBC · February 9, 2021, 10:29 AM

Quote:

Both Redding and Hornady define headspace as the space between the case head and breech face when the case is fully forward in the chamber.

As I said (and as you know,Bart) a maddening amount of dis information is out there.
Redding and Hornady published some incorrect information. They gave a perfect definition for "Head Clearance"

Head clearance and headspace are related but different terms.

A firearm can be made to "perfect" headspace with a chamber reamer and headspace guages and a skilled worker. Its all in the firearm .The nearest round of ammo can be 500 miles away. The ammo is irrelevant to headspace.

However,the symptoms,or problems ordinarily associated with excessive headspace are actually about the resulting excessive head clearance.
Short ammunition can cause excessive head clearance,
Either condition can cause excessive case stretch. Case stretch thins the brass, Case separation can result,
The handloader can tailor ammo to a specific firearm,minimizing head clearance and stretch. The firearm headspace remains unchanged.

The tailored ammo may not work well in another firearm. Tradeoff.

This link will take you to a Varmint Al page, The topic is chamber finish, I'm not suggesting you do anythng to your chamber,but if you scroll down to the "rough chamber" finite element analysis animation, you can see head clearance,case stretch,and thinning in action.

https://varmintal.com/a243z.htm

RC20 · February 9, 2021, 12:49 PM

Back to, the OP asked a question and put it into context.

Its why he is cracking cases feeling its headspace.

We can go all Bart B into the techy weeds that does not respond to that or discuss it in terms of what the OP can do to try to eliminate it technique wise others have done.

Or, I just need to Row The &^*^% Boat Ashore, not learn water physics.

**44 AMP** · February 9, 2021, 03:13 PM

Headspace is a term that has been around since the earliest days of cartridge firearms. It refers, literally, to the space in the firearm where the case head goes.

In the beginning, all cases were rimmed and the first ones were rimfire. The case "head" was the rim, and headspace referred to the space the rim fit in, between the closed boltface and the barrel.

When speaking of rimmed cartridges, which headspace on the rim, where and how bottleneck, rimless and belted cartridges headspace is not relevant.

Specific to the .303 British, and the SMLE rifles, what matters for headspace is where the rim fits. That's all. For military purposes, the rest of the chamber simply has to be big enough for the round to fit into, and being oversized, a little, or a lot, makes no difference at all. An SMLE could have headspace in perfect tolerance and have a chamber grossly oversized and its still fine for service use.

And this is what leads to short case life in SMLEs. The sloppy fit of the case in the chamber, combined with the "min spec" dimensions of sizing dies, and including the fact that ammo is made to be just under "min spec" in size (to ensure fit in min spec chambers.

Add these together and the cases get stretched alot, sized small, and stretched again with each firing/reloading cycle, so they just don't last long, compared to other rifles with "tighter" tolerances.

There are a few commercial .303 British rifles, and their chambers are cut to the usual commercial tolerances, and there are no reports of excessively short case life reloading for those rifles. The problem is that the SMLE is simply NOT a reloader friendly rifle.

You cannot solve this "problem" short of rebarreling the rifle, but you can minimize the effect with careful reloading techniques. And. I wouldn't bother with any sort of "comparator" measuring device(s). Simply neck size fired brass only enough to properly hold a new bullet.

A little trial and error is all that is needed, using your rifle as the "gauge".

Case life won't be great, but done right, you should be able to get 5 or 6 loadings vs. 2-3.

Another point, don't trust "once fired" .303 brass to have its full possible case life. Used to be, I would get "once fired" .303, FL size it once, then neck size only, after that. Then I had a batch that were "fired once" and I FL sized them, and got full case head separation on the next firing.

Now I use only new brass or "once fired" brass from factory ammo that I fired. I don't shoot .303 much anymore, but back when I was doing it regularly, testing new or once fired cases in the rifle to ensure chambering, then sizing only enough to take a new bullet and staying within "normal" pressure limits for that round got me 5-6 loading/firing cycles from the brass, USUALLY. Sometimes a bit more, sometimes a bit less.

Forget all the rest of the info about headspace and how to set your dies using extra tools, gauges and benchrest precision techniques, FOR NOW...

Try the simple stuff, first, and if its doesn't get you anything better, then look at more ...refined...techniques.

Good Luck.

Hope this helps.

PolarFBear · February 9, 2021, 06:04 PM

44AMP. Thanks for the input. Your description is pretty much what I do. All of my "new to me" brass is supposedly once fired. I F/L resize it once. On reloads I only case neck the brass. In my neck of the woods .303 British has always been scarce and even more so now. So conservation of resources is mandatory. Fortunately, this rifle is of later vintage and not one of the "Great War" models. Any inputs on a SMLE chambered for .308.

mehavey · February 9, 2021, 07:00 PM

Quote:

case head separation.

Time for a really dumb observation:
The OP wants to stop/minimize case stretch.

At this point I don't care that the case is supposed to "headspace" on the rim.
We're going to make it "headspace" on the shoulder.

PolarFBear:
- Begin sizing a fired case... gradually
- Sooner or later the dies' going to squish the case in enough that it will actually grow in length even before the die sets the shoulder back
- Keep trying that case in the rifle as you gradually squish-it-in/grow-in-length to the point that the bolt won't close (shoulder too far forward).
- Keep gradually sizing until the shoulder sets back now just enough that the bolt will close again. THAT's where you quit sizing.
- The case now sets up sitting directly on the bolt face, and stopping on the shoulder -- and quits stretching back to the bolt face when fired.

**44 AMP** · February 9, 2021, 10:06 PM

Quote:

At this point I don't care that the case is supposed to "headspace" on the rim.
We're going to make it "headspace" on the shoulder.

Why??

mehavey · February 9, 2021, 10:14 PM

See OP's problem:

Quote:

case head separation.

How do you minimize/stop case head separation in a rimmed bottleneck cartridge ?
Same way you do it in a belted 375 H&H or 300 WinMag.

Ignore the orginal "head"spacing on the rim/belt.
Size for the shoulder.

Bart B. · February 9, 2021, 11:36 PM

Quote:

Originally Posted by mehavey

See OP's problem:

How do you minimize/stop case head separation in a rimmed bottleneck cartridge ?
Same way you do it in a belted 375 H&H or 300 WinMag.

Ignore the orginal "head"spacing on the rim/belt.
Size for the shoulder.

Good idea.

Done right, 15 to 20 maximum loads per case is possible.

mikejonestkd · February 10, 2021, 06:45 AM

Polarbear, I load for a few No4 MK1 enfields and its fairly easy to extend case life.
Both Bart and Mehavey have given good advice on how to do it.

I went a simpler route when loading for .303 brit, I neck size only with a redding Die. I get 15 plus reload per case.

February 8, 2021, 07:26 PM	#1
PolarFBear Senior Member Join Date: April 22, 2015 Location: NE Tennessee, a "Free State" Posts: 478	Head Space??? I've heard this phrase "head space". What EXACTLY is it and how do you measure it? I'm working on a .303 British of 1956 vintage. My brass is not lasting very long, three reloads at minimum levels. Thanks.

February 8, 2021, 08:00 PM	#2
std7mag Senior Member Join Date: June 23, 2013 Location: Central Taxylvania.. Posts: 3,609	In your case, the 303 British, the head space will be measured from the bolt face, to a datum point on the shoulder of the chamber. As far as the cartridge goes, will be the base to a datum on the shoulder of the cartridge. You can get the information from CIP, as it's a European based cartridge. __________________ When our own government declares itself as "tyrannical", where does that leave us??!! "Januarary 6th insurrection". Funny, I didn't see a single piece of rope...

February 8, 2021, 09:51 PM	#3
Nodak1858 Senior Member Join Date: September 7, 2009 Location: N. Dakota Posts: 435	Doesn't the 303 headspace on the rim? __________________ We've all heard that a million monkeys banging on a million typewriters will eventually reproduce the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true.

February 8, 2021, 09:52 PM	#4
rc Senior Member Join Date: April 28, 2001 Location: CA Posts: 1,769	Definitions for Head Space So the most basic definition of head space is the space between your ears On a more serious note, it is the movement front to back that a cartridge has to move in the chamber of a gun when the cylinder, bolt or slide is closed. Some cartridges control headspace on the rim. So a revolver head space is the amount of room the cartridge in the firing position has to slop back and forth in the chamber against the breech face of the revolver and the shoulder on the chamber. Some cylinders have recessed faces and others don't. In auto pistols that headspaced on the rim like 38 auto that was once the space between the back of the barrel chamber and the breech face. Same is true for many rimmed caliber cartridges. However, it was found that setting head space on the mouth of the case leads to more accurate hand guns. So head space for 9mm or modern 38 super as an example is the amount of extra space between the chamber mouth leading to the barrel and the end of the hood which will determine how far forward the slide can go relative to the cartridge. Usually it is minimal. If bullets are not seated deeply enough and bind against the rifling the case will stick up above the barrel hood and the cartridge won't chamber due to insufficient head space for the slide or bolt to close. In bottle neck centerfire rifles the distance between the breech face and the tapered portion of the chamber set head space. Every time you shoot something like a 223 the shoulder bumps forward. Resizing dies bump the case back so it will chamber smoothly in any gun of that chambering. That difference is basically the head space. Neck sizing only sizes the neck to accept a bullet tightly so the head space it technically zero because you are not bumping back the case to standard factory spec.

February 8, 2021, 10:17 PM	#5
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,288	Here we go again!! I suggest you use the search function.You can read for hours what we have already written. Too many people have their own ideas. 1) The flat face with the primer pocket in it is the case head.When the cartridge if fully chambered,the case head's rearward travel is limited by the breech face. 2) The firearm chamber will have a feature to limit and stop the forward movement of the cartridge. This may be a RIM, (example :30-30 Winchester) may be a BELT(example: 375 H+H) It might be the CASE MOUTH (example 45 ACP) or it might be the SHOULDER of a rimless bottleneck case. I'll leave the discussion of "Datum" for an advanced class.At this point,its distracting. 3) HEADSPACE is the distance from the breech face to the feature in the chamber designated to stop or limit the forward travel of the cartridge. Thats it. 4) For us to be able to have a Remington and a Winchester and a Colt,and various ammo manufacturers,some standards were necessary. In the USA,the org that keeps the standards s SAAMI Per SAAMI standards,there are HEADSPACE GAUGES that are used to check the chamber depth is to standard. The "Go" and"No Go" gauge are used to properly chamber and check a newly manufactured gun. A "Field Gauge" is more generous.It is used to determine a worn gun should be taken out of service 5) Note "Headspace" is only about the firearm. All things "headspace" can be established and checked with not one cartridge within 500 miles. 6) The term "Head Clearance" applies to the clearance between the breech face and the case head when the cartridge is traveled forward to stop against the headspace feature of the chamber. Ammunition tolerances and reloading practices are part of head clearance. 7) Number of reloads only matters to those who reload. Those who reload can learn to control head clearance to get more reloads. 303 Brit headspaces on the rim. To do that, the dies size the shoulder to provide clearance at the shoulder. The shoulder defers to the rim. The handloader can say "No" to that. The handloader can adjust the dies to not size the shoulder so much. Then the shoulder is the dominant headspace feature You can control that. In a later post,I can tell you how I do it. Its not the only way Last edited by HiBC; February 8, 2021 at 11:33 PM.

February 8, 2021, 10:47 PM	#6
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Raise your die a few thousandths in the press then resize a fired case to see if it chambers easy. RC & std7mag, note the bold text..... From SAAMI glossary...... HEAD CLEARANCE The distance between the head of a fully seated cartridge or shell and the face of the breech bolt when the action is in the closed position. Commonly confused with headspace. HEADSPACE The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats. 1. BELT: A type of chamber design in which the cartridge seats in the chamber on an enlarged band ahead of the extractor groove of the cartridge body. 2. MOUTH: A type of chamber design in which the cartridge seats in the chamber on the mouth of the cartridge case. 3. RIMLESS: A type of chamber design in which the cartridge seats in the chamber on the shoulder of the cartridge case. 4. RIMMED: A type of chamber design in which the cartridge seats in the chamber on the rim or flange of the cartridge case. Last edited by Bart B.; February 8, 2021 at 11:23 PM.

February 8, 2021, 11:15 PM	#7
RC20 Senior Member Join Date: April 10, 2008 Location: Alaska Posts: 7,014	The OPS issue is not arguing the techy definition of headspace but what to do about a 3 case life limit. Ergo, the 303 has a lot of clearance in the chamber over a sized case as its a battle rifle intended to be in the mud, swamps and sand and you name it. Lot of experience behind it in that regard. And they could care less about brass life, they don't use it but once (we do of course) So, the real issue is can you do something about it? The answer is probably but you have to work at it. First you need to get the Hornady device that goes on the shoulder, a micrometer to measure and then you have to fiddle with your dies to move the shoulder back about .003 and no more. That stops the crunch down and then re-stretch of brass you are experiencing. Another part of that is figuring out if your 303 has the right bolt face to minimize the case movement. All the nitty gritty tech details aside, the rim on a 303 is the basis of reality. Ergo you can minimize how hard the brass works. But, in a 303, you also have that space between the head and the rim that a rebate rim per the 06 does not have. You don't want excess there either. I believe they had like 4 different bolt heads for the 303. I am not familiar with the process but that can be looked up. __________________ Science and Facts are True whether you believe it or not

February 9, 2021, 12:13 AM	#10
Colorado Redneck Senior Member Join Date: January 6, 2008 Location: Northeast Colorado Posts: 1,993	PolarFBear, what is rendering the brass unusable? Split case at the mouth? Case head separation?

February 9, 2021, 12:38 AM	#11
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,288	While this is not the method I use,looking at the product will help you see what needs to be measured,and one workable approach. https://www.hornady.com/headspace-bushings#!/ Unclenick has described getting a hardware store aluminum bushing and resting it on the case shoulder. You might try a .375 hole. The first firing.the cartridge case is fireformed to your chamber. BEFORE you run it into the sizing die,these tools will give you a reference measurement of you case head to shoulder . Its just a measurement to a base line starting point.Once you have a starting point,you can measure change. If you have feeler gages,you can use those between the die and shellholder. Try a .015 or a .020 to start. You backed the die off that much. Lube and size a case,after you write down that base line fire formed length. Bring the die down .005 at a time,using the feeler gages. Measure the case each time till you get a change. Now,I should tell you the length might grow initially. Make note of when you start to shorten the case head to shoulder dimension. Lets say your original base line measurement was zero head clearance I have no SMLE experience. I don;t know how much head clearance they require. Try .003. I've heard about the rear lugs .etc. I try to set my modern bolt rifle ammo at .002 head clearance. You can probably take it from here

February 9, 2021, 06:04 AM	#12
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,333	First, what is causing your short case life? I’m assuming it is case head separations?? As you can see, this is a rimmed case. You need a 303 British field gauge to confirm the rifle is in spec. LINK PTG also has them. The PTG might be a better choice as Forster has a reputation for being overly precise. A field gauge is a no go gauge for rifles that have been shot. The fix if the rifle gauges ok is all in your fireforming of new brass. If you buy new brass and expand the neck to 0.338”, then fl size until it barely fits in the chamber. This false shoulder will blow out the shoulder without moving the brass near the head. Then FL size to only push the shoulder back 0.002” with successive loadings.

February 9, 2021, 06:41 AM	#13
eflyguy Senior Member Join Date: January 1, 2021 Posts: 335	I don't reload, so I'm probably too ignorant to know better, but it strikes me as slightly concerning that someone who reloads - especially a less-than-popular cartridge - doesn't know what headspace is.

February 9, 2021, 09:36 AM	#14
PolarFBear Senior Member Join Date: April 22, 2015 Location: NE Tennessee, a "Free State" Posts: 478	Nathan and ColoradoRedneck- case head separation. "eflyguy", I take great pains on visual inspection of my brass. I suggest you endeavor to learn, or at least try, a hobby before you offer castigation. Walk in "our" shoes. For all replies, THANKS. My only real experience in "head space" issues was an incident of case head separation in a 50 BMG, waaaaay back in my youth. Caught some brass in "near vital" areas. I load this .303 for my son and want to maximize safety. Didn't realize it was SUCH a touchy issue.

February 9, 2021, 09:43 AM	#15
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,288	He is asking the right questions in the right place. We all start somewhere. Ask the question "What is headspace?" and you CAN get a maddening amount of dis-information.

February 9, 2021, 09:52 AM	#16
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Both Redding and Hornady define headspace as the space between the case head and breech face when the case is fully forward in the chamber. https://www.redding-reloading.com/te...with-headspace https://www.hornady.com/team-hornady...nal-ballistics

February 9, 2021, 12:49 PM	#18
RC20 Senior Member Join Date: April 10, 2008 Location: Alaska Posts: 7,014	Back to, the OP asked a question and put it into context. Its why he is cracking cases feeling its headspace. We can go all Bart B into the techy weeds that does not respond to that or discuss it in terms of what the OP can do to try to eliminate it technique wise others have done. Or, I just need to Row The &^*^% Boat Ashore, not learn water physics. __________________ Science and Facts are True whether you believe it or not

February 9, 2021, 03:13 PM	#19
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,846	Headspace is a term that has been around since the earliest days of cartridge firearms. It refers, literally, to the space in the firearm where the case head goes. In the beginning, all cases were rimmed and the first ones were rimfire. The case "head" was the rim, and headspace referred to the space the rim fit in, between the closed boltface and the barrel. When speaking of rimmed cartridges, which headspace on the rim, where and how bottleneck, rimless and belted cartridges headspace is not relevant. Specific to the .303 British, and the SMLE rifles, what matters for headspace is where the rim fits. That's all. For military purposes, the rest of the chamber simply has to be big enough for the round to fit into, and being oversized, a little, or a lot, makes no difference at all. An SMLE could have headspace in perfect tolerance and have a chamber grossly oversized and its still fine for service use. And this is what leads to short case life in SMLEs. The sloppy fit of the case in the chamber, combined with the "min spec" dimensions of sizing dies, and including the fact that ammo is made to be just under "min spec" in size (to ensure fit in min spec chambers. Add these together and the cases get stretched alot, sized small, and stretched again with each firing/reloading cycle, so they just don't last long, compared to other rifles with "tighter" tolerances. There are a few commercial .303 British rifles, and their chambers are cut to the usual commercial tolerances, and there are no reports of excessively short case life reloading for those rifles. The problem is that the SMLE is simply NOT a reloader friendly rifle. You cannot solve this "problem" short of rebarreling the rifle, but you can minimize the effect with careful reloading techniques. And. I wouldn't bother with any sort of "comparator" measuring device(s). Simply neck size fired brass only enough to properly hold a new bullet. A little trial and error is all that is needed, using your rifle as the "gauge". Case life won't be great, but done right, you should be able to get 5 or 6 loadings vs. 2-3. Another point, don't trust "once fired" .303 brass to have its full possible case life. Used to be, I would get "once fired" .303, FL size it once, then neck size only, after that. Then I had a batch that were "fired once" and I FL sized them, and got full case head separation on the next firing. Now I use only new brass or "once fired" brass from factory ammo that I fired. I don't shoot .303 much anymore, but back when I was doing it regularly, testing new or once fired cases in the rifle to ensure chambering, then sizing only enough to take a new bullet and staying within "normal" pressure limits for that round got me 5-6 loading/firing cycles from the brass, USUALLY. Sometimes a bit more, sometimes a bit less. Forget all the rest of the info about headspace and how to set your dies using extra tools, gauges and benchrest precision techniques, FOR NOW... Try the simple stuff, first, and if its doesn't get you anything better, then look at more ...refined...techniques. Good Luck. Hope this helps. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

February 9, 2021, 06:04 PM	#20
PolarFBear Senior Member Join Date: April 22, 2015 Location: NE Tennessee, a "Free State" Posts: 478	44AMP. Thanks for the input. Your description is pretty much what I do. All of my "new to me" brass is supposedly once fired. I F/L resize it once. On reloads I only case neck the brass. In my neck of the woods .303 British has always been scarce and even more so now. So conservation of resources is mandatory. Fortunately, this rifle is of later vintage and not one of the "Great War" models. Any inputs on a SMLE chambered for .308.

February 10, 2021, 06:45 AM	#25
mikejonestkd Senior Member Join Date: January 3, 2006 Location: Brockport, NY Posts: 3,717	Polarbear, I load for a few No4 MK1 enfields and its fairly easy to extend case life. Both Bart and Mehavey have given good advice on how to do it. I went a simpler route when loading for .303 brit, I neck size only with a redding Die. I get 15 plus reload per case. __________________ You are the bows from which your children as living arrows are sent forth.