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  #1  
Old 02-14-2017, 10:55 PM
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Excessive pressure


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I cleaned about 200 pcs of brass and then I inspected them as usual. Two of them had blown primers with case head expansion. Disconcerting to say the least. I have loaded maybe a couple hundred thousand rounds in my life. MG shooter. The ammo was loaded with the same powder, same tips, Mostly LC and a lesser amount of RA brass. Both damaged cases were RA. Not sure how many times the brass has been reloaded. Mixed primers , Wins or Rem, loaded on a Dillon 1050 and every finished round is weighed on a digital scale in order to detect any gross errors. Average pressure signs are what I would consider perfect. Shot 110 rounds of the same loads last weekend with no pressure issues. Yes I know that the 1050 will load the very first round with slightly more powder because there are 4 turret spaces before the first round receives a powder charge. I always remove the first round and manually remove the 2 extra grains before proceeding.
Periodic inspection of powder charge, head space and OAL. When any lot of brass shows more than a couple wear signs, separations or split necks I throw the whole lot into the scrap bucket and start over with once fired brass.
OK guys why these sudden high pressure cases. This issue with the blown primers is not something I am used to seeing ?????

Last edited by zebcoboy; 02-14-2017 at 11:03 PM.
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Old 02-15-2017, 03:38 AM
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What gun are you shooting, what caliber are you loading and what load are you using?
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Old 02-15-2017, 03:38 AM
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Is your load high density? if not you could have had low neck tension and pushed a bullet into the case during feeding. i find Remington brass to be "softer" or more ductile. you dont mention the firearm but some semi autos are hard on brass.
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Old 02-15-2017, 06:38 AM
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Quote:
I cleaned about 200 pcs of brass and then I inspected them as usual. Two of them had blown primers with case head expansion.
I believe you should dump everything and start over. You do not know what chamber your rifle has, you do know what make and or model the rifle is. You did managed to get the R-P case part, around here there is no shortage of R-P cases. If you developed a problem with soft headed R-P cases you should have made that discovery with the first firing. To accomplish that you are required to measure before firing and again after. Today there is no answer but in the old days before social media case head expansion was considered to be normal with .00025" expansion.

Start over: The last chance a reloader has to discover a mistake is just before pulling the trigger for the last time. If the reloader knew the weight of the case, powder charge and weight of the bullet he would know what the finished round should weigh.

I loaded 250 30/06 rounds on a Dillon Rl 550B, there was a spread of 16 grains between the heaviest and lightest, for me? Not a problem, I used 5 different cases, there was 16 grains difference between the heavies and lightest cases meaning I did not have too much powder and the bullets were all the same weight.

Again there is nothing entertaining about pulling the trigger with no clue about what is going to happen next.

F. Guffey
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Old 02-15-2017, 11:38 AM
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You mentioned that this involves a machine gun, fully auto stuff. Unfortunately all any of us can do with the limited information you've provided is guess. But the fact that you did include a vital clue, that being this occurred in a machine gun, I'd say a couple bullets could have set back while cycling into the chamber, that'll certainly drive pressures up real good.

So what is it you are loading for? .50 BMG, .223, BAR or other?

What powder and charge are you running?

SMOA
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Old 02-15-2017, 01:58 PM
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Quote:
Both damaged cases were RA
Different components = Different pressure.

Quote:
I always remove the first round and manually remove the 2 extra grains before proceeding.
Lets hope so.

I load slow, looking into each case before seating a bullet.
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Old 02-15-2017, 03:13 PM
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Excessive pressure

Believe it or not I cannot identify the powder. European flake pull down powder ( I call it V49 can't even remember how I came up with that name ) that came from some experimental cartridges that FN made during the race for the NATO cartridge. Then we shoved the .308 down NATO's throat. Bought a lot of it long ago and have been using it exclusively in my .308 loads. Works very well in both 223 and .308. The gun is a 1917A1 Browning water cooled. .308 caliber 38 GR and 150 gr tip. Normally no excessive pressure issues just these rare cases. One time I was shooting my AR-15 with a HP bullet and found that the HP bullet was not feeding up the feed ramp and was getting pushed back into the case. Similar issue. Added a Lee crimping die to my process and that was the end of that issue. I use a Lee crimping die in my .308 process also. When weighing the finished rounds RA ( Rock Island Armory ) rounds weigh about 5 gr less than finished LC ( Lake city ) finished rounds. That's just the difference in the manufacturing companies. When you are loading 1000 at a time the only thing you can do to avoid a serious issue is to weigh the finish round hoping to catch a really questionable round. I do make visual inspections every so often and check an occasional charge on the scale. Never an issue.
The 1917 pulls the round rearward from the belt then centers it right in front of the chamber. No feed ramp. I just check the OAL of both of the cases in question and both are well within limits. However these rounds will not fit into the shell plate because of the swelling. OK guys. Need your input.
PS using a Dillon 1050 progressive press.

Last edited by zebcoboy; 02-15-2017 at 06:33 PM.
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Old 02-15-2017, 05:51 PM
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Every case I've seen from a 1919 is not fit to reload and I probably created a dump truck load of empties in the Army. I collected brass but not THAT brass.
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Old 02-15-2017, 06:29 PM
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Brass

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Originally Posted by JBelk View Post
Every case I've seen from a 1919 is not fit to reload and I probably created a dump truck load of empties in the Army. I collected brass but not THAT brass.
Actually the once fired brass came out of M-60 guns. I have closely examined thousands of rounds that have come from my Brownings and have reloaded them as much as 5 times. A lot depends on how the headspace is set on the gun.
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Old 02-15-2017, 09:03 PM
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You sure you want to use brass that was exposed to seriously high pressures, especially in a MG. I'm just kind of surprised, you referred to case head expansion and pierced primers concerning excessive pressures in your original post. I wouldn't think the primer pockets would but barely hold a primer.

SMOA
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Old 02-16-2017, 07:28 AM
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seriously and actually:

I do not get into mortal combat with reloading, one of my favorite dies is the 308 W case forming/trim die. I have 16 forming dies, the 308 W is my favorite because it is short, my second favorite is the 243 W forming die , it is another favorite for the same reason because it is also short. And then there're are belted forming dies, same thing; I find advantages to short forming dies.

Typing slower: I did not say short/fat forming dies. And then there is the thing with measuring before and again after. I form 308 W cases from 30/06 cases. There are times 308 W chambers are generous, I off set the generous chamber neck with the thicker case body.

F. Guffey
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Old 02-16-2017, 07:36 AM
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There are times 308 W chambers are generous, I off set the generous chamber neck with the thicker case body.
By golly! A point of commonality! I formed 6mm Remington cases from '06 Match brass for the same reason. Usually just a skim cut off the neck gave a near BR fit and I was shooting HCBR at the time.
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Old 02-16-2017, 08:47 AM
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Looking at the issue from a different point of view, I'll have to ask..........Are you SURE the cases are all the same length? It could be a simple matter of a short case not getting enough crimp to keep the bullet from being pushed back into the case! In any case (no pun intended), I'd be checking the adjustment of your crimping operation. Oh, by the way ....................WELCOME TO THE FORUM!
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Old 02-16-2017, 04:34 PM
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Bon Son Bok

That is why I use the Lee crimping Die. The Lee die does not use a forced angle concept which requires really consistent case length. The Lee die uses a collet that crimps from the side just like commercial ammo crimps. Never ever resulting in a buckled shoulder from a longer than normal case.
I'll tell you I am totally baffled by those two bad cases. I will be a lot more observant of my procedures and fired cases till I find the cause of this sudden high pressure. The crazy thing is all the other fired cases look great and all look identical. I weighed some new loads today and one finished round weighed a few grains heavier so I broke it apart. 38.0 gr of powder just like it is supposed to be.
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Old 02-17-2017, 05:44 AM
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Originally Posted by zebcoboy View Post
I weighed some new loads today and one finished round weighed a few grains heavier so I broke it apart. 38.0 gr of powder just like it is supposed to be.
If you did not weight before loading and sort/match components you wasted your time.

If you crimped the case and at the same time crushed the case at the case body/shoulder juncture the case would be difficult to chamber.

F. Guffey
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Old 02-17-2017, 09:44 AM
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Originally Posted by zebcoboy View Post
That is why I use the Lee crimping Die. The Lee die does not use a forced angle concept which requires really consistent case length. The Lee die uses a collet that crimps from the side just like commercial ammo crimps. Never ever resulting in a buckled shoulder from a longer than normal case.
I'll tell you I am totally baffled by those two bad cases. I will be a lot more observant of my procedures and fired cases till I find the cause of this sudden high pressure. The crazy thing is all the other fired cases look great and all look identical. I weighed some new loads today and one finished round weighed a few grains heavier so I broke it apart. 38.0 gr of powder just like it is supposed to be.
Zebcoboy, help me out here...............Were the two Remington cases SHORTER than the rest? Does the Lee crimper still make an adequate crimp regardless of the cases length? You see, I'm thinking that these shorter cases without a good crimp had their bullets slide down into the case body, thus creating an over-pressure situation!
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Old 02-17-2017, 10:32 PM
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Bong Son Buck

The more I think about your comment the more sense it makes. There is a finger on the extractor that positions the cartridge in front of the chamber. I set up my gun and cycled a dummy round to just in front of the chamber. I could not make it move enough, even with strong pressure, to hit the end of the barrel. The spring tension on that finger seems comparable to my other extractors. The Izzi barrel has a large radius on the chamber. The closest position to hitting the barrel would be at the bottom and there is no evidence of copper scuffing anywhere on that radius.
Not to say that you are wrong but I could not make it happen manually. You really got me going on this possibility. I am going to look harder at this. That would explain a lot. Going shooting again Monday.
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Old 02-18-2017, 06:52 AM
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Was the RA brass loaded with Winchester primers? There have been problems in the past. Primer Gas Leak Slideshow by joe1944usa | Photobucket
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Old 02-18-2017, 05:15 PM
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Primers

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Originally Posted by 243winxb View Post
Was the RA brass loaded with Winchester primers? There have been problems in the past. Primer Gas Leak Slideshow by joe1944usa | Photobucket
My issues do not seem to be like this. I do use Win primers when available. No bolt face erosion. I think BSB has the most likely evaluation of the problem but I cannot tell you why this is happening.
Just a little funny. I'm weighing my finished ammo today and all the sudden, bingo, a round that weighs 30 some grains less Ah ha! So I take it apart 35gr of powder ( my tracer load ) What! Then I look at the case head 7mm-08??? must have picked it up while cleaning up at the range. Duh. Makes great looking ammo though. Ha Ha.
Back to the original problem, found another round without a primer. Found the primer later. the primer pocket was a few thousands oversize. Could this just be a problem of soft brass. Remember I load hundreds at a time. I don't know.
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Old 02-19-2017, 06:03 AM
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Originally Posted by zebcoboy View Post
. Ha Ha.
Back to the original problem, found another round without a primer. Found the primer later. the primer pocket was a few thousands oversize. Could this just be a problem of soft brass. Remember I load hundreds at a time. I don't know.
Suddenly and without warning?? The primer pocket became .002" too large?

We need to determine who is installing the primers, around here I am the primer installer, when a primer is installed I feel it being installed, when installing a primer I get wrist whip lash I know it. Again, I do not get into mortal combat with reloading, every time I seat a primer I anticipate that good 'good primer seating feel', when the handle on my auto primers hits the bottom like swoosh with no resistance I suspect the primer is too small in diameter or the primer pocket is too large in diameter.

And then there is the term relative; if the case head is soft the primer pocket can increase in diameter and at the same time the case head increases in diameter and the case head gets shorter from the cup above the web to the case head and the flash hole increases in diameter. It reminds me of those famous last words before the rifle is rendered scrap; that would be "it must have been a double charge". No one measures before and again after.

F. Guffey

Last edited by fguffey; 02-19-2017 at 06:08 AM.
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