Range Report what causes this?

[pe5b]

I have a POF 308 that runs perfect and has proven to be a sub moa shooter. I tried different factory loads in 168 & 175 and it seems to shoot Hornady 168gr AMAX the best (FGMM 168 close second)
So I find a better deal on 168gr TAP FPD AMAX and confirm with Hornady other that the nickle plated cases its the same load. I shot 2 boxes today and some of the primers are sticking up after being fired. I had 10 rounds left (out of 60) of the match 168gr AMAX and i fired them also. All shot fine and seemed to be the same except for the primer issue. Both boxes of the tap had 5 or 6 like this, What does this indicate? How alarmed should I be? All other ammo has had primers look like the ones that are not sticking up.

 

[Advokaten]

Re: what causes this?

In my book that would be significant of two things,

one that the rounds were on the short end of SAAMI/CIP second there is a bit of primer flow around the firing pin.

Best regards Chris

 

[vman]

Re: what causes this?

It would not raise an alarm in my book.

They do not look flattened, and are a factory load.

 

[Wild_Bill]

Re: what causes this?

the primers are not flattened but there is some clearence around the firing pin andfiring pin hole in the boltface. if you can get another firing pin that is larger and will fill the hole better it should stop some of the flow back around the firing pin. when you reload use a CCI primer as they are harder than the other primers. The standard CCI military CCI or the Win military primers would be a better choice as the thicker cup will stop the flow back in the primer.

As long as the primers do not pierce you will be OK but if you get any blanking the centre out then stop using them because you will gas cut the firing pin and get gas through the trigger and it will end up blowing holes in every primer you use. the other thing try some Win or Rem match and see what happens as they should be using harder primers. But i would look at reloading the cases doen the track and the CCI Semi Auto primer is a great place to start i think it is a CCI34.

 

[Tulie]

Re: what causes this?

I agree with the others, those primers aren't flat at all and that flow is more than likely due to a less than tight firing pin. I wouldn't worry about it either.

 

[Teggy1]

Re: what causes this?

I have the same thing in my REM 700. Light to max loads all look the same, as well as factory. I use CCI 200's and get the same thing. No primer flattening, but very slight cratering on everything (start loads to well over book max).

 

[pe5b]

Re: what causes this?

Thanks to all for the replies. I'm relieved to hear its not serious. Its just strange that its only on the nickle plated Hornady brass but not the non plated Hornady brass.

 

[bowslngr]

Re: what causes this?

I disagree, especially since you are not seeing the same symptom with other types of ammo. What you are seeing is a symptom of high port pressure. I have seen this with several different ARs paired with different types of ammo. Here is what I think is happening:
Your action is unlocking and trying to extract the round before the brass has had a chance to shrink back down enough. The brass doesn't budge for a split second, but your bolt opens up a very slight gap behind it. Pressure pushed the weekest part of the primer (the area that was pushed forward by the firing pin) backward into the gap before the cartridge is finally extracted.
If I am right, you have a pressure problem, but not the kind that will get you into real trouble. You are just operating at the very edge of what your semi-auto action can handle and still cycle realiably.

 

[CTone03]

Re: what causes this?

My LR308 does that with every cartridge I fire, factory or handload, and my handloads are all on the light side. I wouldn't worry about it.

 

[pe5b]

Re: what causes this?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bowslngr</div><div class="ubbcode-body">I disagree, especially since you are not seeing the same symptom with other types of ammo. What you are seeing is a symptom of high port pressure. I have seen this with several different ARs paired with different types of ammo. Here is what I think is happening:
Your action is unlocking and trying to extract the round before the brass has had a chance to shrink back down enough. The brass doesn't budge for a split second, but your bolt opens up a very slight gap behind it. Pressure pushed the weekest part of the primer (the area that was pushed forward by the firing pin) backward into the gap before the cartridge is finally extracted.
If I am right, you have a pressure problem, but not the kind that will get you into real trouble. You are just operating at the very edge of what your semi-auto action can handle and still cycle realiably. </div></div>

If this is the case would a heavier buffer slove this? And if so would it be a fix or a band-aid? I agree since its only one ammo doing this,but the Hornady amax match & amax tap should be the same load other that different lot # and plated brass.

Edit: Could the plated brass take just a hair longer to shrink and cause this compared to plain brass?

 

[bowslngr]

Re: what causes this?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hoosier</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bowslngr</div><div class="ubbcode-body">I disagree, especially since you are not seeing the same symptom with other types of ammo. What you are seeing is a symptom of high port pressure. I have seen this with several different ARs paired with different types of ammo. Here is what I think is happening:
Your action is unlocking and trying to extract the round before the brass has had a chance to shrink back down enough. The brass doesn't budge for a split second, but your bolt opens up a very slight gap behind it. Pressure pushed the weekest part of the primer (the area that was pushed forward by the firing pin) backward into the gap before the cartridge is finally extracted.
If I am right, you have a pressure problem, but not the kind that will get you into real trouble. You are just operating at the very edge of what your semi-auto action can handle and still cycle realiably. </div></div>

If this is the case would a heavier buffer slove this? And if so would it be a fix or a band-aid? I agree since its only one ammo doing this,but the Hornady amax match & amax tap should be the same load other that different lot # and plated brass.

Edit: Could the plated brass take just a hair longer to shrink and cause this compared to plain brass? </div></div>

A heavy buffer may take care of it, but an adjustable gas block or adjustable gas tube would probably be the better solution if you are dead-set on shooting the TAP.

I hadn't thought about the plating question. It could be what is causing this, but I think the plating actually makes a brass case more slippery. Maybe not when it is under pressure and heat? Good question.

Have you pulled apart one of each of the match ammo and the TAP to make sure they are, in fact, indentical? You may find that the powder is visibly different or of an different weight. Have you also checked the OAL of the two loads to make sure they are seated to the same depth. Just some thoughts.

 

[pe5b]

Re: what causes this?

I dont have any of the non Tap amax left to compare. I did weigh one each to compare them when i had both and they were the same.
I can swith to the surpressed setting on my POF and try that.

 

[valentine]

Re: what causes this?

I would not be scared, because there a primer cups of different hardness/different material properties of the sheet metal the primer cups were made of. Some time ago there was an article on 6mmBr.com about this.

 

[Ares]

Re: what causes this?

Look better guys, there are signs of ejector. Factory loads could be overpressured too

 

[CharlieTN]

Re: what causes this?

According to our Winchester rep, Hornady uses their primers for their loads. I'm not sure if that's all of their loads.

Typically Federal primers are the softest of the bunch with CCI being quite a bit harder.

I would be a bit concerned with these loads. Looks like a bit extra pressure. Probably not enough to go blowing things up but when you're dealing with a fairly high pressure round in the first place, I er on the side of caution.

Just my 2 cents worth, which is probably worth just that.

Charlie

 

[John L]

Re: what causes this?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Ares</div><div class="ubbcode-body">Look better guys, there are signs of ejector. Factory loads could be overpressured too </div></div>

I second this one. Between the primers and the ejector marks I'd say there are some pressure problems.

 

[Rob01]

Re: what causes this?

My POF leave those ejector marks on any brass. Not a sign of pressure in the POF.

 

[bigwheeler]

Re: what causes this?

I've never seen anything to support harder or softer primers, they are either
thicker cupped or thinner. The actual material they are stamped out of is supposedly the same. In any case it just takes a couple of blown primers to
gas cut your firing pin. I would not shoot those anymore if it were me. There is
no apparent bolt swipe on the heads so the bolt is not opening under pressure
unless it is not showing in the photos. The ejector marks do mean the pressure
is a little high but at the same time It's somewhat common and shouldn't be
something to be overly concerned with.

 

[bowslngr]

Re: what causes this?

#1 and #3 do show swipes, but they are not very significant.

edit: Also, correct me in I am wrong, but I think that <span style="text-decoration: underline">raised</span> ejector marks are a sign of high pressure...not ejector imprints.

 

[AUJohn]

Re: what causes this?

P/T curve differences due to the brass difference.

 

[TDECK]

Re: what causes this?

What would be a result of firing these Hornady 168 AMAX rounds out of a bolt gun? Would it be less of an issue. I have quite a bit of this round that I bought for a bolt gun. I have not had a chance to shoot it yet. What do you think?

 

[Rob01]

Re: what causes this?

I have shot literally thousands through my .308 bolt gun with different barrels and never had an issue.