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Bad brass causing over pressure.

T

tomcatfan

Sergeant
Full Member
Minuteman
Nov 22, 2010
953
704
41
Southern MD.
#1
So as I gain experience reloading, I’ve been excited to try as many variables in components as possible so that I can hone in what works. With that being said, I do understand that each individual component makes the round successful when they truly work for the gun they are being shot from. However I recently found that brass has a major impact on that.

I went to the range yesterday and was shooting a starting load of 155gr A-max behind 44.0 grains of IMR 4895 (this is only .5 grains higher than the starting load) at 100 yds to get an idea how successful this load could be out of my rifle. I was using once fired brass from match ammo that I shot out of my rifle with a PPU head stamp. The match ammo shot fairly well so I figured I would keep the brass and give it another run. That just didn’t work out though. I’m not exactly sure why but that brass gave me overpressure signs (flat primers, in one case a completely ejected primer, and difficulty ejecting) at only .5 grains above starting load. I was nowhere close to the do not exceed charge of 47.5 grains as stated by IMR. The rounds didn’t group that bad, but this is the first time I’ve gotten overpressure signs out of my rifle.

Needless to say I’m throwing this brass away and I’m sticking with Nosler, and Lake City. Has anyone else had a similar experience?
 
#3
Re: Bad brass causing over pressure.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body">We are going to need more info:
Case: PPU
primer: ???
powder: I4895
charge: 44 gr
bullet: 155 Amax
OAL: ??
pictures of pressure signs on the cases

You should also be aware that there are signs of pressure created by loads that are to LOW in charge weight! See:
http://www.shootingsoftware.com/pressure.htm </div></div>

I will put up pics when I get home, but the rest of the info is as follows:

Case: PPU
primer: CCI #200
powder: IMR 4895
charge: 44 gr
bullet: 155 Amax
OAL: .01" Jump to the Lands in my rifle for this round

This raises a good point. I understand that I could get pressure signs if the bullet doesn't have any jump into the lands as compared to those who do. But I measure my loads from the ogive, not COAL. I load up my 175 smk's and 178 A-maxes to the same ogive depth. I loaded the 155's to the same ogive depth to the ogive as my 175 smk's. Is there an error here?

The way I undestand it, this method takes out the variable of the overall rounds length. This is especially important with Hornady's A-max's as they have a polymer tip. Measuring from the ogive gives you the true jump to the lands.
 
#4
Re: Bad brass causing over pressure.

Maybe...you know that you aren't measuring to the actual leade of the chamber, but to an artificial diameter that your ogive tool maker has machined. Since you brought that subject up, take a 155 and stick it in the chamber and establish a length using your ogive tool and see if it is the same. Publish your findings, please. Good luck. FNP
 
#5
Re: Bad brass causing over pressure.

Over sizing the brass; and/or case lube left on the case (even a very slight trace of it); and/or oil in the chamber, can give the same results.......
 
#6
Re: Bad brass causing over pressure.

So I did go back home and measure the ogive into my chamber for the 155 and it measured 2.226" with the set up I have. So I seated the rounds at 2.200" which give it 0.026" of jump. But as requested here are some of the pics of the primers. This is the most clear cut case of overpressure I've seen personally. The primer pockets are FLAT and there are actually marks on the back of the brass from my extractor. These marks can be seen best on the top left and bottom right round.

mv3xir.jpg


The one case you see with out a primer, that is not because I pulled it. It fell out as I extracted the round. I'm not sure why or how for that matter, but thats how it came out of my chamber.
 
#7
Re: Bad brass causing over pressure.

Your recipe as you've indicated it should NOT give you pressure problems....

Is your chamber's headspace correct?

Is your sizing die set up to size as minimal an amount as possible so to NOT create a headspace issue with the brass?

Are you cleaning the sizing lube off of the cases before firing them?

Are you leaving gun oil in the chamber?

Is your bolt face free of excessive oil?

Is your powder charge weighing system proven and correct?

Is there a chance, however remote, that your powder is compromised and not what you think it is?

You make out like you've loaded Nosler and LC brass before this, no similar issues with that?

Personally I wouldn't shoot that rifle any more until you get to the bottom of this...........
 
#8
Re: Bad brass causing over pressure.


Is your chamber's headspace correct?

My chamber is fine as I shot a 175 smk with 44.0 grains of varget, with Nosler Brass, CCI 200 primers, and with 0.020" of jump into the lands right after shooting the PPU rounds and it was fine. No pressure signs and I shot .380" 3 round group at 100 yds (before people start, I know 5 round groups are used to measure accuracy).

Is your sizing die set up to size as minimal an amount as possible so to NOT create a headspace issue with the brass?

Are you cleaning the sizing lube off of the cases before firing them?

For sizing die, I only shoot reloaded brass that has been fired from the same gun. With that being said I use a Lee neck sizing die which does not require lube. And die headspace shouldn't be an issue as I have reloaded many other brass types through the same die and fired them just fine.

Are you leaving gun oil in the chamber?
There was nothing in the chamber as the loads I was testing before and after shot just fine.

Is your bolt face free of excessive oil?
Not a problem as I was firing prior to using this load. They all shot fine.

Is your powder charge weighing system proven and correct?
Yes I use an RCBS 505 balance scale. I made these rounds just after making the batch with the varget above. I always check my zero before reloading any rounds.

Is there a chance, however remote, that your powder is compromised and not what you think it is?
This may be a very very remote chance, but I do not cross pollinate my powders. I clean my bench off after I use a specific powder and start over prior to using a new one. Plus Varget and IMR 4895 have very different colors. It is pretty easy to tell between the two. I also use IMR 4895 in my .223 rem loads and there were no pressure signs there.

You make out like you've loaded Nosler and LC brass before this, no similar issues with that?
No sir, thats why I feel pretty confident that this is a brass thing. I feel like with all the variables at hand, the only thing I could reduce it to was the brass.

I just wanted to see if anyone else has had this experience. I know there are a lot of people on here that have many years of doing this stuff.
 
#9
Re: Bad brass causing over pressure.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Savage 10fp</div><div class="ubbcode-body">

But I measure my loads from the ogive, not COAL. I load up my 175 smk's and 178 A-maxes to the same ogive depth. I loaded the 155's to the same ogive depth to the ogive as my 175 smk's. Is there an error here?

</div></div>

Aren't you supposed to check the ogive for each different bullet that you use ? As the number will more than likely change.
So was the ogive number the same for the 155's when you checked it again as it was with the 175's ?
 
#10
Re: Bad brass causing over pressure.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AtOne</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Savage 10fp</div><div class="ubbcode-body">

But I measure my loads from the ogive, not COAL. I load up my 175 smk's and 178 A-maxes to the same ogive depth. I loaded the 155's to the same ogive depth to the ogive as my 175 smk's. Is there an error here?

</div></div>

Aren't you supposed to check the ogive for each different bullet that you use ? As the number will more than likely change.
So was the ogive number the same for the 155's when you checked it again as it was with the 175's ?
</div></div>

I'm sorry for the confusion here. I do measure each round's distance into the lands. When I said they were loaded up to the same ogive depth, I meant from the lands. Each round (155, 175, and 178) are loaded to a different lengths, but I load it up to the same ogive to the lands distance.
 
#11
Re: Bad brass causing over pressure.

I was just airing out some other variables...seems like you have it under control.

It's only brass, pitch it and start over with something else.

No big deal........
 
#12
Re: Bad brass causing over pressure.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I load up my 175 smk's and 178 A-maxes to the same ogive depth. I loaded the 155's to the same ogive depth to the ogive as my 175 smk's. Is there an error here?

</div></div>

I'd say you were jammed into the lands if you didn't adjust your seating die for the 155 bullet after loading the 178's.
Got that big pressure spike from that.

If there is absolutely no way you cross contaminated your IMR powder with another then.......

Only other thing I can think of is your scale was possibly out of zero. Which was already mentioned above. 4895 is pretty mild, I used to run it 1.5gr over max listing with palma bullets with no pressure signs in a Tikka 595 MS. I would give that brass one more go before tossing it bro. Load up 10 with that new seating depth and see if that don't fix it.



Hope you solve this one.
 
#13
Re: Bad brass causing over pressure.

Thanks for everyone's input. But AtOne sent me this link:

http://www.thehighroad.org/archive/index.php/t-501655.html&amp&

which someone else wrote in with the same exact thing including the ejector marks on the back end of the brass. I guess my google skills have been outmatched. Thank you AtOne.

It should go without saying but I pulled the rounds that I did have loaded with that brass, and I threw them away. I just want to share this information to the community. Thanks for everyone who had an input. It was a good exercise and more importantly I have learned a little bit from it.

Also for everyone's record I got this brass from Prvi Partizan Match ammo. Not saying anything bad about this ammo, but I would be careful in using the brass for reloading.
 
#15
Re: Bad brass causing over pressure.

good lookin out ATone
grin.gif

Pretty recent thread you found there. Probably same batch of brass.
Curious to see how much water those cases would hold, has to be case wall thickness reducing capacity.
 
#17
Re: Bad brass causing over pressure.

I wouldn't say that PPU is shitty brass for reloading. Perhaps there are just some bad batches going around. I would use caution in using them though. Personally I'm throwing away any brass that has a headstamp from a place that I don't recongnize. This is a mistake that I only need to make once.

Also FYI, I did get some PPU head stamped ammo from BootRiver Valley match ammo as well.
 
#20
Re: Bad brass causing over pressure.

I'll add this random thought....

It doesn't matter one damn wit if some errant lot number of brass has a reduced capacity, and is deemed "bad" by the masses. Working back <span style="font-weight: bold">UP</span> to a load with any change in component is abecedarian Reloader 101.

Never assume anything, and always prove things out for yourself...........
 
#21
Re: Bad brass causing over pressure.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tripwire</div><div class="ubbcode-body">I'll add this random thought....

It doesn't matter one damn wit if some errant lot number of brass has a reduced capacity, and is deemed "bad" by the masses. Working back <span style="font-weight: bold">UP</span> to a load with any change in component is abecedarian Reloader 101.

Never assume anything, and always prove things out for yourself........... </div></div>

I'm not going to argue this point one bit, as your absolutely right. But if you look at the loads above. They are at the starting loads as recommended by Hogdon. This was the starting point for anyone working UP.
 
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