Visual Pressure Signs

warbirdlover · January 26, 2012, 11:12 PM

I used to watch the primers when developing a load and when the corner radius started "flattening" I'd back off to where it didn't and that was my max. load.

I don't reload anymore but what do you guys look for regarding getting too high pressures? Is there a better way without buying some expensive piece of equipment?

Brian Pfleuger · January 26, 2012, 11:46 PM

UncleNick's rather exhaustive list...

http://www.shootersforum.com/showthread.htm?t=58763

Sevens · January 27, 2012, 12:54 AM

That's a phenomenal list. Been a while since I've read it.

As for "reading primers", we all do it, but it's important to understand what you are looking at and to be able to do it in context. It's information-- but it ain't much information, and the information that if offers is all relative.

What I mean is, if you are visually comparing your primer on a .357 Mag round, with a Winchester primer, a charge of 2400 and a 158 grain bullet and you are comparing THAT primer to some others that you loaded exactly the same but with one full grain less of a powder charge, then you are looking at some real information. Compare the 13.5 grain charged primers to the 14.5 grain charged primers and notice the difference.

If, however, you are looking at that .357 case and comparing it to what you see on your 9mm loads, you may as well skip the step entirely because they have nothing to do with each other.

Some guns, some loads, some particular brass... will make a primer look hotter or flatter or (whatever, insert a descriptor here) than others.

So certainly look at it, but compare like items before you make any wild assumptions with what you see.

mehavey · January 27, 2012, 06:22 AM

I've come to realize that of UncleNick's list, two "threshhold" signs stand out as hard to misinterpret (other than something so way over the top as to invoke HolyCow! rating):

1. The primer pockets get get noticeably easier to seat into/if not unusable after 4-5 firings. (You are 10% over brass rating and should back off 5-8% in powder charge)

2. You begin seeing ejector cutout "smears" on the case head/bolt is sticky to open. (You are at least 20% over brass rating and should immediately cease work/pull remaining bullets/back off 10-12%)

Primers are next to useless these days, and measuring subtle web expansion has fallen by the wayside (although primers falling out is a web expansion corollary)

warbirdlover · January 29, 2012, 01:03 AM

I guess I should explain how I did it (after reading some article on it many years ago). I always used the same primers (Remington and Remington magnum). I made sure the factory ammo primers (Remington CoreLok) weren't flattening. Then I worked up my load (very carefully) until it "appeared" that the primer corner was starting to flatten. This was never severe as I didn't jump powder charges up much. When I hit that point where it "kind of" looked like they "might" be flattening I backed down to the previous load and that was it. I still always watched it when shooting at the range. It seemed to work good because I could always get pretty close to or even at the max. charges. Always used the same brass too (Remington) and the same bullets (either Nosler partition or Sierra).

From John Wooter's safety tips...

Watch for signs of high pressure while working up a handload. This means extraction difficulty (however slight), flattened primers, cratered primers, ironed-out headstamps, polished headstamps, ejector marks, case-head expansion, and excessive recoil and muzzle blast. And anything else whatever that strikes you as abnormal about the load.

mrawesome22 · January 29, 2012, 01:44 AM

I was gonna post that a chronograph is the only true pressure gauge we have unless we install pressure gauges into our chambers, but I realized I'm too tired to argue

amathis · January 29, 2012, 07:52 AM

I had an interesting situation arise yesterday. I was out with a buddy who I am teaching to reload to test fire his new rounds. On the first round the primer looked a bit flattened and had worked out a bit. These are once fired brass, head stamps looked good, no ejector marks. The whole situation was odd, and I knew we couldn't be over pressure because the Chronograph. Chronograph was saying we were perfect for a starting load.

My point is that primers are one indicator of high pressure and alone are not necessarily indicative of danger. Some loads just do funny things to primers and some primers are very susceptible to pressure. Primer reading is either hit or miss. I'd rather trust my Chrony.

FatWhiteMan · January 29, 2012, 09:27 AM

Quote:

I was gonna post that a chronograph is the only true pressure gauge we have unless we install pressure gauges into our chambers, but I realized I'm too tired to argue

Good point but of course that is not without some variables as well. I was working up loads for an old Spanish Mauser and was getting close, but not quite to the muzzle velocity of the target load when I started getting some pressure signs. It took me a moment to remember that the original load was done in a full length Spanish Mauser with a 29" barrel. Mine was an old '93 Mauser but had the barrel cut down to 24" decades ago. I did a quick calculation and determined that if considering the difference in MV between the two barrel lengths, I was approaching max.

BTW--I think we may be neighbors. I'm in the Ohio Appalachian foothills as well.

F. Guffey · January 29, 2012, 12:29 PM

Amathis, “On the first round the primer looked a bit flattened and had worked out a bit” and then “primers do some strange things” When primers work out ‘a bit’ the reloader should look the other way as in the opposite of looking for pressure signs and start looking for the lack of pressure signs. I have not seen the cute little demonstration/illustration/cartoon that is believed to explain, to the reloader, everything they would ever need to know about the sequence of events after pulling the trigger, the firing pin jumps out, chases down the primer, after catching the primer (after the case shoulder hits the shoulder of the chamber etc., etc..) the firing pin strikes the primer and then things pick up, it is believed, anyhow in that sequence of events the case and primer are forward of the bolt face, by design the case head must finish against the bolt face, if the primer is ‘worked out a bit’ it can only be said the primer made it back to the bolt face but the case head did not.

When the primer backs out it looses the support of the primer pocket, then there is time, time is a factor.

F. Guffey

amathis · January 29, 2012, 03:39 PM

Quote:

Amathis, “On the first round the primer looked a bit flattened and had worked out a bit” and then “primers do some strange things” When primers work out ‘a bit’ the reloader should look the other way as in the opposite of looking for pressure signs and start looking for the lack of pressure signs. I have not seen the cute little demonstration/illustration/cartoon that is believed to explain, to the reloader, everything they would ever need to know about the sequence of events after pulling the trigger, the firing pin jumps out, chases down the primer, after catching the primer (after the case shoulder hits the shoulder of the chamber etc., etc..) the firing pin strikes the primer and then things pick up, it is believed, anyhow in that sequence of events the case and primer are forward of the bolt face, by design the case head must finish against the bolt face, if the primer is ‘worked out a bit’ it can only be said the primer made it back to the bolt face but the case head did not.

When the primer backs out it looses the support of the primer pocket, then there is time, time is a factor.

F. Guffey

That's exactly what we determined after running the numbers. An additional sign was that there was soot on the case neck meaning there wasn't enough of a seal. We figured the lack of pressure was not forcing the round back against the bolt face. As soon as we have some nice clear weather and the Chrony will cooperate, we're going to run some higher loads.

My original post was to clarify that primers can flatten in numerous situations not just over pressure. Reloading reminds me of the slogan of the board game Othello: A minute to learn, but a lifetime to master. Reloading is an easy thing to learn, but to learn the intricacies of a firearm, and to know exactly what caused what takes a lifetime.

January 26, 2012, 11:12 PM	#1
warbirdlover Senior Member Join Date: December 13, 2009 Location: central Wisconsin Posts: 2,324	Visual Pressure Signs I used to watch the primers when developing a load and when the corner radius started "flattening" I'd back off to where it didn't and that was my max. load. I don't reload anymore but what do you guys look for regarding getting too high pressures? Is there a better way without buying some expensive piece of equipment?

January 27, 2012, 12:54 AM	#3
Sevens Senior Member Join Date: July 28, 2007 Location: Ohio Posts: 11,756	That's a phenomenal list. Been a while since I've read it. As for "reading primers", we all do it, but it's important to understand what you are looking at and to be able to do it in context. It's information-- but it ain't much information, and the information that if offers is all relative. What I mean is, if you are visually comparing your primer on a .357 Mag round, with a Winchester primer, a charge of 2400 and a 158 grain bullet and you are comparing THAT primer to some others that you loaded exactly the same but with one full grain less of a powder charge, then you are looking at some real information. Compare the 13.5 grain charged primers to the 14.5 grain charged primers and notice the difference. If, however, you are looking at that .357 case and comparing it to what you see on your 9mm loads, you may as well skip the step entirely because they have nothing to do with each other. Some guns, some loads, some particular brass... will make a primer look hotter or flatter or (whatever, insert a descriptor here) than others. So certainly look at it, but compare like items before you make any wild assumptions with what you see. __________________ *Attention Brass rats and other reloaders:* I really need .327 Federal Magnum brass, no lot size too small. Tell me what caliber you need and I'll see what I have to swap. PM me and we'll discuss.

January 27, 2012, 06:22 AM	#4
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,896	I've come to realize that of UncleNick's list, two "threshhold" signs stand out as hard to misinterpret (other than something so way over the top as to invoke HolyCow! rating): 1. The primer pockets get get noticeably easier to seat into/if not unusable after 4-5 firings. (You are 10% over brass rating and should back off 5-8% in powder charge) 2. You begin seeing ejector cutout "smears" on the case head/bolt is sticky to open. (You are at least 20% over brass rating and should immediately cease work/pull remaining bullets/back off 10-12%) Primers are next to useless these days, and measuring subtle web expansion has fallen by the wayside (although primers falling out is a web expansion corollary) Last edited by mehavey; January 27, 2012 at 06:43 AM.

January 26, 2012, 11:46 PM	#2
Brian Pfleuger Moderator Emeritus Join Date: June 25, 2008 Location: Austin, CO Posts: 19,578	UncleNick's rather exhaustive list... http://www.shootersforum.com/showthread.htm?t=58763

January 29, 2012, 01:03 AM	#5
warbirdlover Senior Member Join Date: December 13, 2009 Location: central Wisconsin Posts: 2,324	I guess I should explain how I did it (after reading some article on it many years ago). I always used the same primers (Remington and Remington magnum). I made sure the factory ammo primers (Remington CoreLok) weren't flattening. Then I worked up my load (very carefully) until it "appeared" that the primer corner was starting to flatten. This was never severe as I didn't jump powder charges up much. When I hit that point where it "kind of" looked like they "might" be flattening I backed down to the previous load and that was it. I still always watched it when shooting at the range. It seemed to work good because I could always get pretty close to or even at the max. charges. Always used the same brass too (Remington) and the same bullets (either Nosler partition or Sierra). From John Wooter's safety tips... Watch for signs of high pressure while working up a handload. This means extraction difficulty (however slight), flattened primers, cratered primers, ironed-out headstamps, polished headstamps, ejector marks, case-head expansion, and excessive recoil and muzzle blast. And anything else whatever that strikes you as abnormal about the load.

January 29, 2012, 01:44 AM	#6
mrawesome22 Senior Member Join Date: November 9, 2005 Location: Ohio, Appalachia's foothills. Posts: 3,779	I was gonna post that a chronograph is the only true pressure gauge we have unless we install pressure gauges into our chambers, but I realized I'm too tired to argue

January 29, 2012, 07:52 AM	#7
amathis Senior Member Join Date: March 20, 2009 Location: Champlain Valley, Vermont Posts: 161	I had an interesting situation arise yesterday. I was out with a buddy who I am teaching to reload to test fire his new rounds. On the first round the primer looked a bit flattened and had worked out a bit. These are once fired brass, head stamps looked good, no ejector marks. The whole situation was odd, and I knew we couldn't be over pressure because the Chronograph. Chronograph was saying we were perfect for a starting load. My point is that primers are one indicator of high pressure and alone are not necessarily indicative of danger. Some loads just do funny things to primers and some primers are very susceptible to pressure. Primer reading is either hit or miss. I'd rather trust my Chrony.

January 29, 2012, 12:29 PM	#9
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	Amathis, “On the first round the primer looked a bit flattened and had worked out a bit” and then “primers do some strange things” When primers work out ‘a bit’ the reloader should look the other way as in the opposite of looking for pressure signs and start looking for the lack of pressure signs. I have not seen the cute little demonstration/illustration/cartoon that is believed to explain, to the reloader, everything they would ever need to know about the sequence of events after pulling the trigger, the firing pin jumps out, chases down the primer, after catching the primer (after the case shoulder hits the shoulder of the chamber etc., etc..) the firing pin strikes the primer and then things pick up, it is believed, anyhow in that sequence of events the case and primer are forward of the bolt face, by design the case head must finish against the bolt face, if the primer is ‘worked out a bit’ it can only be said the primer made it back to the bolt face but the case head did not. When the primer backs out it looses the support of the primer pocket, then there is time, time is a factor. F. Guffey