Partial full-length sizing rifle brass

[steveNChunter]

Since I've been reloading, I've either FL sized or neck sized all my rifle brass. When using a FL sizing die (most of mine are Lee) I have just set the die per the instructions and started sizing. I've read about the benefits of partial FL sizing and setting the shoulder back no more than .002 and getting better accuracy and longer brass life. How do I set my die up to properly do this? I want the benefit of reliable, easy chambering that FL sizing offers, and the longer brass life.

I just bought some new Lapua .308 brass and I want to make it last as long as possible.

[603Country]

I almost hate to get this started, since there are strong opinions from several directions. You'll hear that you need feeler gauges to do this well, but I'll give you the basic simple way that will work just fine. You just want to set the case shoulder back far enough to allow the fireformed case to chamber without force. At some point, after being fired some number of times, your fired cases are going to require a bit of force to chamber them. When you are at that point, back your FL die out and run a fireformed case up into the die. Screw in the die until you feel it reach the case. lower the case from the die and screw the die in a small amount (1/8th of a full turn) and size the case. Try that case out in your rifle and if the shoulder is still being compressed, screw the die in a touch more and size the case again. Try it out in your rifle again. At some point, you'll feel the case chamber without compression. There's where you lock the die in place.

I used to call this Partial Resizing, but now I call it "almost FL resizing".

There are more scientific ways to do this, and Mr Guffy will explain that soon, but the above will work just fine.

Another approach, which is what I'm mostly doing these days, is to use a Lee Collet Die to size the neck until after some number of firings the case gets a bit tough to chamber. Then use a Body Die from Redding to set the shoulder back when necessary.

[Bart B.]

Partial full length sizing has traditionally meant using a full length die set to size most of the case neck down, size the body down but it doesn't touch the case shoulder. This typically moves the shoulder forward enough to cause the bolt to bind when the round's chambered because as the fired case body diameters are reduced, that brass has to go somewhere so it pushes the case shoulder forward. Lots of folks think the partially full length sized case binding a bit when the bolt's closed helps center the case shoulder in the chamber. Well, it does then the bolt head twists to different places for each shot. So does the impact of the firing pin driving the case forward a thousandth or two centering the case shoulder in the chamber shoulder a few microseconds before the primer fires and the bolt is locked up in battery in the same place for every shot.

Such partial full length sizing has never proved to be all that good for best accuracy because the bolt head doesn't lock up in battery in the same place for each shot. Especially when the bolt face isn't square with the chamber axis.

Full length sizing has never meant the shell holder in the press has to stop against the full length sizing die's bottom. But some insist this is the only real way to full length size. As long as the case body and neck diameters are made smaller and the case shoulder is set back some amount, full lenght sizing's happened because the full length of the case that can be sized has been sized.

You'll need a case gauge to measure the shoulder's distance from the case head to size cases the way you mention. An RCBS Precision Mic or Hornady LNL Gauge will do the trick nicely. Even a nylon bushing whose inside diameter matches a point somewhere on the case shoulder used with a caliper to measure the difference in head to shoulder before and after full length sizing a fired case as shown in post #35 in:

http://thefiringline.com/forums/show...t=nylon&page=2

Use it to measure your fired case headspace then set the die in the press so it's a couple thousandths less after full length sizing. Adjust the die 1/36th turn to move it .002" in height. Using one of these labels helps a lot:

http://s860.photobucket.com/user/jep...ent-1.jpg.html

One can also use shellholders of different heights to make the die's bottom stop different distances from its bottom where the case head rests. Redding makes them in sets of 5 each one .002" higher stepped from the industry standard shellholder height of .125"....

http://www.redding-reloading.com/ind...ellholder-sets

This method of full length sizing fired bottleneck cases has been used for decades producing the most accurate ammo used by rifle shooters getting best accuracy as well as very long case life. But it takes tools to accurately measure the case and set the die. Consistant case lubrication keeps the sized case headspace spread in a small range.

A lot of this "nomenclature" and "terminology" one uses to describe some reloading process gets confusing. One can make up their own name for a procedure to do some specific thing with specific tools. When there's several or dozens of descriptive lexicons used and none are the same, confusion starts and ends up destroying any meaningful communication.

[JefferS]

I've started to experiment with this a bit. My approach (and I don't have years of experience like many, just reloading a couple of years) was to get the L.E. Wilson Case Length Headspace Gage for this purpose. I have the .308, but I'm mainly using one for my .30-06. I had to watch some Youtube videos from the manufacturer a few times to internalize what they were saying, but it does make sense to me now.

Although my once-fired brass does not show my head space increasing on my current gun, the theory with this gauge is that you can measure the actual headspace post fire and do exactly what you're talking about by adjusting your dies to reduce the length by about 0.002. Before this, my approach was more like 603Country. The Wilson gauge started with my semi .308 (more important to check for good feeding), but I liked the gauge enough that I got one for my .30-06 bolt.

[Goatwhiskers]

Re: the method advocated by 603Country. IMHO this is true FL sizing. You are full length sizing the case to precisely fit the chamber of "your" rifle. The conventional method at least theoretically resizes the brass to factory specs which in a given case may actually be overworking the brass. Witness the fact that you can use this method to size brass for a rifle that has slightly excess headspace and get case life equal to anyone else, the difference is that the loaded round may not fit someone's else's rifle. I have used his method on cases for my 30/40AI for many years and have gotten over 20 loadings from them. YMMV. GW

[steve4102]

1. Put the Shell Holder in the press and raise the ram.

2. Screw the Full Length(FL) Die into the press so it is about a dimes thickness" above the Shell Holder.

3. Lube a "Fired" case (walls and inside the neck) and size it.

4. Remove the Lube and try closing the bolt on it in the chamber.

5. If the bolt closes with no resistance, screw the FL Die into the press about 1/8-1/4 turn and repeat steps 3 & 4.

6. As you feel the resistance begin, slow down how much you screw the FL Die into the press so you are at about 1/16 of a turn, or "Fine Tuning". At some point you will not be able to close the bolt and you are extremely close to having the FL Die in the proper position.

NOTE: The reason for this is because the FL Die has begun Resizing the Case-walls down to the Pressure Ring. As it does so, the Case-body lengthens slightly which in turn moves the Case-shoulder slightly forward. Then as the "Fine Tuning" continues the Case-shoulder makes contact with the FL Die and is moved slightly reward(or slightly shortens the Case-head to Case-shoulder dimension).

7. Stop when there is a slight bit of resistance when closing the bolt on the empty case. You now have a "slight crush fit" for the case in that specific chamber, or Zero Headspace.

8. You can leave your die set here for a "crush fit" or you can screw it into the press just enough to set the shoulder back your desired amount.
Once you get it where you want it, take some masking tape or a black marker and put a Witness Mark where the FL Die Lock Ring is positioned to hold the FL Die in this position. Loosen the FL Die and return the Lock Ring to align with the Witness Mark and sung up the Set-Screw.

Or you can avoid all this and get a Stony Point/Hornady case gauge kit, found here.

http://www.midwayusa.com/product/479...ProductFinding

[steveNChunter]

Thanks guys for all the great advice. I'm probably going to try 603Country's method first and see how it works for me. I have a couple rifles I do some benchrest shooting with, and I use my collet neck sizing dies for those, but I am mostly concerned with easy chambering, longer brass life, and good hunting accuracy for this particular rifle I'll be loading for.

It started life as a '71 model Rem 700 BDL .243. It's now at the gunsmith being rebarreled with a factory contour 16.25" long 1:10 twist .308 barrel which I'm having threaded for a muzzle brake. I'm also getting the whole barreled action Cerakoted graphite black and the bolt handle threaded for an aftermarket knob. I have a Boyd's featherweight thumbhole stock here at the house waiting for it. It's going to be my lightweight hunting rifle/truck gun, and like all my rifles, I'll have some fun with it at the range.

[Bart B.]

Steve4102, on screwing down a sizing die in tiny steps.....

Stop when there is a slight bit of resistance when closing the bolt on the empty case. You now have a "slight crush fit" for the case in that specific chamber, or Zero Headspace.

Zero headspace? How can that be?

I'm confused. Headspace on rimless bottleneck cases, chambers and measuring gauges all have some finite length from their back end to a reference diameter on their shoulder. For the .308 Win., they're all a few thousandths around 1.630". So, how can a case have "zero" headspace?

I think you mean "head clearance" which is the space between the case head and bolt face when a cartridge is full forward in the chamber stopped against its headspace reference point.

[F. Guffey]

After a member declares the case has head space there is no going back, I have never found a mention of case head space before the Internet, point, SAAMI says the case has a length , SAAMI says the case has a length (BASIC) from the datum to the case head, SAAMI makes no mention of case head space. I have been told it is not much of a stretch of the imagination to superimposed the two drawings etc. etc.. I off set the length of the chamber with the length of the case from the shoulder of the case to the head of the case, I am the fan of cutting down on all that case travel.

Bart B. is suggesting reloaders adjust the die with guestimates of rotation of the die in degree then converted to thousandths. And, I ask why. He is suggesting precision based on wild guesses with no verification. He could suggest verifying the adjustment with a feeler gage, but for pretty smart ‘fellers’ it would not take them long before they realize making the wild guestimate of a degree of a turn and converted to thousandths is a waste of time then suddenly realize time would be saved and precession would be accomplished by going straight to the feeler gage to make the adjustment. I go straight to the verifying tool, the feeler gage.

There are not many tools I do not have, I have many tools I do not need and or use, A member was making reference to precession in the terms of dollars, seems he had a value of $2.000 on a set micrometers, I have a Fuller height gage valued at $2.600, a Pratt and Whitney electronic gage that starts at .000005” and a Japanese made box type micrometer that has a dampener, pull the spindle back and let it go then read the setting. I get all the precession required for reloading from a plate with a hole drilled in it or a Wilson Case gage, straight edge and a feeler gage.

I have presses and dies, I control the length of the case from the shoulder to the head of the case by adjusting the die. No where does it say I must fire a case first, so? I choose not to. I use cases that have been fired in trashy old chambers, that would be cases that have been fired in long chambers, chambers that are long from the datum/shoulder to the bolt face. Meaning? The cases will not chamber. Instead of using nickels, dimes and or quarters I use the feeler gage to adjust the case off of the shell holder, in the perfect world .005” minus a few would be perfect but many chambers have additional length between the shoulder and bolt face, so I start by adjusting the die off the shell holder .008”. For those with presses that have excessive flex and have no ability to overcome the cases resistance to sizing. the die must be be adjusted to overcome the presses weakness.

I start by measuring the length of the case before firing from the shoulder to the head of the case. WHY? After sizing I can compare the two cases as in before firing and after sizing, I would know ‘what will chamber’ and the effect sizing had on the case. I do not have those days when after sizing a case it will not chamber.

And again, when a case whips my press and my press fails to size a case I know by how much, I can measure the gap between the top of the shell holder and bottom of the die, after all, when the die is adjusted to full length size the die is adjusted down to and below the shell holder with an additional 1/4 turn, when the cases resistance to sizing increases the die is adjusted an additional 1/4 turn to make it 1/2 or .0355”.

F. Guffey

I've read about the benefits of partial FL sizing and setting the shoulder back no more than .002 and getting better accuracy and longer brass life.

I have read that also, for me it is about ‘HOW’ they adjust the die , I ask, and they get all snarky, 10 years ago I was told it was impossible, now everyone is doing it, that brings us to the “.002” further back”.
I know the length of the fired case from the shoulder to the case head before I fire it.

F. Guffey

[243winxb]

http://www.brownells.com/.aspx/lid=1...nd_Maximum_COL

[4runnerman]

Just get a fl bushing die

[243winxb]

Necks go first. Bushing die & no expander for longer brass life, as said above.

[steve4102]

Originally Posted by Bart B.

I think you mean "head clearance" which is the space between the case head and bolt face when a cartridge is full forward in the chamber stopped against its headspace reference point.

There ya go, that's the term I will use from now on.

Thanks.

[F. Guffey]

Originally Posted by Bart B.
I think you mean "head clearance" which is the space between the case head and bolt face when a cartridge is full forward in the chamber stopped against its headspace reference point.

There ya go, that's the term I will use from now on.

Thanks.

I am not a member of the admiration society, I would agree but in an effort to take short cuts we fail to explain why one case has case head separation and others have what papers to be an immunity.

And I ask "Have you ever scribed a case at the case body/shoulder juncture before firing?"

Before someone gives Bart B. credit for inventing the term head clearance I suggest they read SAAMI definitions.

F. Guffey

[Bart B.]

Steve, regarding zero headspace or when there's a slight crush fit of cases in the chamber when the bolt closes on them. . . . .

Benchresters noticed this happening in their tack-drivers after 4 to 5 neck only fired case sizing. Every shoot and resize cycle caused case headspace to grow a few ten-thousandths inch. Starting with 1 to 2 thousandths of head clearance, when it got to zero (or even minus a few ten-thousandths), their bolt heads would no longer twist into the same place for each shot. Their tiny 5-shot groups at 100 yards started getting bigger and more "fliers" appeared. The solution was to use a die that set the fired case shoulders back 1 or 2 thousandths then start over again. This would repeat after 4 or 5 more neck sizing routines.

All of which is one reason why most of the stool shooters full length size their fired cases nowadays. The fired case body is sized down a thousandth or so as is its shoulder set back that much. This ensures no more zero (or less) headspace as well as the occasional binding of neck only sized cases' slight out of round condition not indexing right in slight out of round chambers (neither are perfectly round anyway) as their body diameters grew a bit with each firing.

[old roper]

Bart B, Got a question and pretty simple to answer. Your always refer to Benchrest shooters to point out what their using.

Where do you get your experience to quote what BR use?

[Bart B.]

Directly from them via email to queries I emailed them or their posts in forums related to benchrest shooting.

If you're referring to my remark about why most of the stool shooters full length size their fired cases nowadays, note that the smallest fraction over 50% of them (that's most of them) full length sizing their fired cases qualifies my comment. Some of them still neck only size their cases as do some competitive shooters in other disciplines. And they do pretty good, to.

[F. Guffey]

Old Roper, good question, when dealing with bench resters they make it very clear there is at least $2,000 difference in what I am shooting and what they are shooting, some times more. I have rifles that make it difficult to improve the accuracy, one I bid on and won for $120.00 for parts, another last ditch Mauser, I thought the bullets were tumbling and another that I paid $150.00 for, a Fanta Fe.

Accuracy for those rifles is not about talking it to death, it is a matter of reloading, 12 different loads of 10 rounds each, I have built a few rifles, one rifle with a stock from Richard's Micro fit, I told them I thought I could train wood peckers to do a better job. I gave the new owner 12 different loads of 10 rounds each with the understanding he would take the rifle and ammo to the range to determine what the rifle liked. He fired one round of each group of 10 then adjusted the scope to zero, to him the rifle liked everything.

12 different head stamps, from new to once fired and military cases with different dates.

F. Guffey

Then there is the qualifying statement. bench resters get snarky when I ask questions like "What is the difference in length between a fired case and a full length sized case when measured from the shoulder to the case head, one of my not-so accurate rifles has a long chamber, the difference in length between the chamber and a minimum length sized case is .016", that would be .016" case head clearance if the case could get away from the bolt face, instead it has .016" clearance between the shoulder of case and the shoulder of the chamber. Accuracy improves when I form 280 Remington cases to 30/06 cases for a chamber that is long from the shoulder back to the bolt face. I could full length size the cases as recommended by Bart B., but I am the fan of cutting down on all that case travel. I add .014" to the length of the case from the shoulder to the case head and accuracy improves. And I say time is a factor.

[old roper]

Bart B. Benchrest shooters are not shooting factory rifles and most chambers are not SAAMI spec did you happen to ask what their shooting?

http://bulletin.accurateshooter.com/...d-agg-records/

[Bart B.]

Some were asked, others not. I don't remember the cartridges nor do I think that matters.

I know the benchresters don't use factory rifles nor SAAMI spec chambers. But other disciplines do use SAAMI spec chambers in their custom rifles full length sizing their fired cases and getting the same accuracy as the benchresters do. They, too, have shot a few 5- and 10-shot tiny groups at 1000 yards.

J. O'Hara, mentioned in that link, uses Harrel full length bushing dies in his rifle; 'twas mentioned in it. Would like to see the sizes of the rest of his dozens (hundreds?) of other 5- and 10-shot groups that agg'd larger than those mentioned for the record. Benchrest records are statistical anomolies that end up cancelling out all the variables or all of those variables are zero; there's no way one can determine which one it was. They represent the best accuracy attained for a few shots representing about 1 percent of all groups shot.

Sierra Bullets learned decades ago testing their stuff in commercial bolt action sporting rifles as well as custom match rifles with all sorts of chambers and barrels that full length sizing the fired cases from them used in developing load data made the test groups the smallest. But they only have several thousand rounds of test data to back that up.

It's not a matter of what or who made the chamber. It's how much and what parts of fired cases from them are sized. It's oft times mentioned on 6mmbr that one piece full length sizing dies make case necks better centered on case shoulders.

[old roper]

Bart B. maybe to you it doesn't matter but custom chambers required custom dies which may require custom reamer for those die.

Average reloader walks and buy FL sizer doesn't have that type option must less maybe turning neck.

If groups don't matter why you send that group into Kreiger? You sure didn't shoot it at a match.

[4runnerman]

old roper--Welcome to the new world of bench shooters. I shoot a stock savage F Class rifle. There are many now shooting Savage Axis in 223 and 308. The steps for doing your brass are the same regardless of rifle. Bench shooters are just a little pickier than most. Custom dies are not needed. Good to have but not needed. My new barrel I just put on this year has a very tight chamber. I did need to buy a small base die to size my brass, but that is a one time process and after that first time in a small base die I am right back to my Forester die from there on.

I think most Bench shooters now are FL sizing with a bushing die. Not to many fire form there brass any more. There is no gain in accuracy by doing so.

[Bart B.]

In response to your remarks, old roper, read on......

maybe to you it doesn't matter but custom chambers required custom dies which may require custom reamer for those die.

I don’t think that’s necessary. Many folks use standard commercial dies making sized cases with body dimensions different amounts smaller than the chamber and get accuracy equal to what the benchresters get with custom, chamber matching dies.

Average reloader walks and buy FL sizer doesn't have that type option must less maybe turning neck.

Sorry; don’t quite understand what you’re asking about. Try again, please.

If groups don't matter why you send that group into Kreiger?

Groups matter if you’re testing stuff for accuracy. I sent Jack Kreiger that group to show him what that barrel would do with standard full length sizing dies on unprepped fired with Sierra’s then new bullet in cases shot in my rifle in what’s now F class positions.

You sure didn't shoot it at a match.

Of course not; I wanted to see how it performed with minimal human and atmospheric intervention to evaluate the ammo and rifle. There's no wind or mirage variables at 5 AM. Nobody shoots groups on bullseye targets slung up in prone in competition as small as they do testing ammo in rifles rested on something or clamped in free-recoiling accuracy cradles. You’ve been told that before.

[old roper]

4runnerman, thanks for the Welcome but as ex BR shooter got some first hand real world experience with dies need for that game. We have to give warning about loads for non SAAMI spec not sure why that should include dies. It is a money game in BR as cost of dies is no big deal and you sure not going to walk in to LGS and buy a set.

Never shot F-Class and said if I did it would open as those rifle pretty muck like BR rifle use same actions for me be right bolt left port. got Clark Fry and Speedy down in Raton build rifles and had couple BR rifles that Speedy build good gunsmith.

Getting experience from E-Mail new one for me.

[Bart B.]

Nobody gets "experience" from e-mail. Just information.

Sierra Bullets uses Redding full length bushing dies (same as LGS stock) resizing their fired cases from rail guns to shoot their best match bullets at 200 yards as accurate as benchrest rifles do in matches.