pressure signs

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gmac

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I am new to reloading within the last year, so if my question is dumb please forgive me.
I was under the impression that when the primer in your cartridge flattens out after shooting that it is a sign of too high pressures. My factory federal premium tsx' s, in .338wm, flatten the primer in my rifle. I have worked my loads up to 69.5gns H4350 with the same tsx's as my federal premium (225gn fbtsx) but don't know if I should go any higher due to flattening of the primer.
Am I way off base? Is flattening the primer ok?

Thanks
 
Primers are not great indicators of pressure.
As long as your primers are of the same lot they can indicate _relative_ pressure; but, if they are a different lot, all bets are off.

The most reliable indicators of pressure are:
Case head expansion (0.0003 over a factory load is usually max)
Velocity (when adding more powder results in less velocity gain than expected)
And case condition and extraction difficulties (sticky case and extractor/ejector marks on the head).

Of course the best way would be with a piezo strain gauges like this http://www.oehler-research.com/model43.html
 
(0.0003 over a factory load is usually max
Click to expand...
That would be ######xerror:rolleyes: :) ? and depending on the case :redface:
As for the primer, flat is pretty hot, I like 3/4 flat, with little or no built up around the firing pin dent. :) Thanks for picking that up fellas :D Got good marks in Math, just been a long time :)
 
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No, I meant 3, 10-thousandths of an inch expansion in excess of the expansion produced by a factory load.
Assuming you are using a once fired case, and it has been resized back to factory spec.

So let's say the head (just in front of the belt) on that factory .338 starts at 0.5130, fired it expands to 0.5151, resize it back to 0.513, pack it with your favourite stuffing, pop it again, if the head measures more than 0.5154 you are a little on the warm side.
If you neck-size the brass this won't work, because the brass will just continue to expand, and if you use older brass this won't work because it will work-harden.
And obviously one round is not proof. average of 6 will give a good indication.
 
That would be .003 right? and depending on the case .0015-.002 normal
Click to expand...

I measure off of the belt itself(or the thickest part of the web if there is no belt).Case head expansion with most factory loads averages .0002" to .0005".
 
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Standard loads?

First, when reloading, do you stay within the component manufacturers' specs?
Do you follow the reloading manual data to the letter "T"?
Or did you extrapolate?

For your Federal factory loads, it is also possible that your rifle has a tad more headspace and the primer has time to protrude a bit before the pressure peaks and it is riveted by the case stretching to the boltface.
I would take a measurement of an unfired round and measure the same brass once fired.
If your cases's shoulder has been pushed just a bit further, consider keeping it that way and do not full-length resize your fireformed brass.
Do not headspace on the belt; do it on the shoulder, it will be much better for your brass' life.
Maybe try a powder just a tad slower, too; it could help with heavy bullets.
Good luck!
PP.:)
 
Thanks for the replies. They're very helpful to a rookie.
So basically flattened primers are a pressure sign but how much of a sign must be determined by measuring the case length etc.?

Thanks
 
First, when reloading, do you stay within the component manufacturers' specs?
Do you follow the reloading manual data to the letter "T"?
Or did you extrapolate?

Sorry,I didn't answer your questions in my last reply. I have been using cci large magnum primers working loads from 64gns up to 69.5gns. I have kept the overall cartridge length the same as factory loads, basically following the reloading manual data to the "T". Maybe a slower powder is something I should try. I used h4350 as it seems to be the best (read cheapest) way to load my 30-06 as I've read that h4350 powder works well for both calibres.

Thanks
 
Here is some data,great stuff in facthttp://http://forums.accuratereloading.com/eve/forums/a/tpc/f/2511043/m/316101735

You don't have to read through it all,but near the bottom there is a picture of primers. I think those pressures are only guesses,and low ones at that. Different brass cup shapes vary,in his Winchesters the primers didn't flatten like they do in my Federals. Still ,it will give you an idea of primer apperances
 
It's not just cup shape, although it is something to take into account, but different lots of primers will have different thicknesses of metal. Also the anvils may be seated at different depths. Like it or not, even though they are from the same manufacturer and bear the same label, not all primers are created equal. When I was shooting Hunter Bench Rest, we were very careful to buy up primers (bench rest) that were of the same lot, usually enough to last the life of the barrel. I'm still in the habit. Just because a particular lot of primers is different doesn't mean it won't be accurate or more important consistant. It may show high pressure signs or may not, with little or no difference in velocity or verticle spread. A definite sign of higher pressures is verticle increase of groups. Especially with the same bullet. Downwindtracker is putting you onto a great site, go look. Do not exceed manufactures reccomended specs and especially don't use information from loading manuals that don't coincide with the bullet make that you are useing. Just because Barnes or Sierra or Hornady bullets are the same weight, there are so many variables, such as metallurgy and bearing surface lengths, that there will definitely be huge variances in pressure. Just follow the rules and you will be fine. If you're really concerned, go join a local club and talk to some of the more knowledgeable members. By the way don't just glom onto the nearest 20 year old because he is the closest to your age, some are extremely knowledgeable but usually have a hard time getting accross the neccessary information in proper sequence, ask for advice at a meeting, the average club member will be happy to share his or her knowledge. bearhunter
 
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Also be wary of getting in over your head.


There is lots for you to learn, and it really is important that you proceed from a firm foundation.

If you read a lot of the posts in this forum, you'll come across a couple posts of new reloaders asking which progressive or semi-progressive press they should get as their first press. In the replies you'll read that most of us old (20+ years of reloading) reloaders recommend a single station press, it's not that we want to trap anyone in the dark ages or be patronizing, it's not that we think "If it was good enough for me, it'll be good enough for you!", it's that most of us really believe that there are lessons and processes that are learned best on a single station.
 
Brain seized,:redface: I ment primer pockets sides,but cups are different hardness,too. I know CCI-200 are softer than WLR.

Standard pressure loads in rifle with excess headspace will hammer the primers flat,but you should see protruding primers in the starting loads. Or primer cratering with mid-level loads, could mean your firing pin hole is too large.I have had both.Both are exceptions to the rule

"I should also point out that some may find the charges a bit over the top, but i need to stress each and every barrel/chamber combination is a lawn to it self, the barrel in this series of tests was a new BORDER barrel, the lands on this barrel is very NARROW and is of the 5R type that Boots obermyer incoroperates into his barrels, and these barrels just eat more powder
in my hunting rifle i have got a walther barrel, which has got a really wide lands, i had to drop the charges 2-3 grain to reach the same velocities as on the spread sheets
So for those that want to use these spread sheets to work up loads start 5 grains below the max charge , and then work up till you hit you desired velocity , once you are there you are in the ball park of that pressure ...pressure testing was done on a 24 inch barrel, if useing a 22 inch barrel just subtract 30 fps and you will be at the desired pressure , with a velocity of 30 fps less than on the spread sheet..... "

Going over that post again I noticed this,so I added it.
 
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Pressure sign is at best an inexact science.
Lots of factory loads produce flattened primers.
The condition of your rifle example headspace can produce false pressure sign.
Looking back a few decades, CIL produced 303 british ammo that was hot enough to be scrapped for reloading when fired in a typical SMLE with lots of headspace.
Do not assume your rifle is perfect.
Go slow, and read lots.
 
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