Flattened/punctured primers: should I be worried?

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Jackal

Jackal

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After running about 100rds through my new DPMS G2 .308, I noticed that my primers are getting flattened and 1 even punctured. I've tried Guardian, Winchester, Freedom Munitions, PPU, Brown Bear, Aussie F4, ZQI and a couple others. They have all exhibited the same symptoms.

Should I be contacting customer service? It doesnt seem normal for a $1000 rifle.:scrutiny:
 

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While the primer strikes don't look bad it's hard to gauge from the picture what is going on. Obviously a punctured primer is not normal. I would be looking at my firing pin and try to measure firing pin protrusion. How does the firing pin look? Nice and rounded or jagged? Not sure how to measure protrusion on a DPMS G2. As a general rule, centerfire rifles and handguns usually measure between .050” and .060”. Since you have such a wide range of ammunition I would be looking at the firing pin. Which one (manufacturer) was the punctured one, I can't make out the headstamp?

Ron
 
Here's a better pic. The puncture was with ZQI Guardian. I know the rifle is over gassed, but now I'm wondering if headspace might be an issue. The firing pin was fine, until the pierced primer apparently flame cut it, which concluded my outing.
 

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The firing pin could be looking better after getting flamed but when a pierced primer happens the firing pin pays the price. With the new pictures while they don't overly look flat there may be a little bit of primer extrusion in there. Hopefully another member who sees more than I do will weigh in on this. The cartridge on the right seems to show some extrusion. This is where a headspace gauge would be nice to check the chamber. You may want to call customer service and tell them what you have, I would like to see more thoughts and opinions here.

Ron
 
there is probably 1 of 3 things going on

1. Chamber cut a bit small or has dirt in it, causing over pressure
2. firing pin got cut and will now pierce primers even when not overpressured.
3. an excessive amount of copper is in the barrel causing over pressure.

curious if you did a barrel break in
also curious if you've scrubbed the chamber and/or barrel since this started happening


i'd definitely replace the pin and do a thorough cleaning until you stop getting copper out of the barrel
 
curious if you did a barrel break in
also curious if you've scrubbed the chamber and/or barrel since this started happening


i'd definitely replace the pin and do a thorough cleaning until you stop getting copper out of the barrel
Click to expand...

Rifle has less than 100rds through it since new, this is the barrel break in. Chrome lined 4150 barrel. Chamber's clean. Would loose headspace cause this?
 
ok thanks. break-in for me is always under 10 rounds, usually under 5 rounds.

i don't see how headspace would cause it. is something else leading you to that conclusion?
 
7 or more different brands of ammo in 100 round . Defect in the ammo?

Pierced or Blanked Primers. -------------------------------------------------------------------------------- 1. Check the firing pin, it should have no gas cutting or deformities. 2. Firing pin protrusion should be checked. Internet search shows .055" to be about right for bolt actions. For an AR15., Colt and S&W M&P 15 armorer manuals uses a GO dimension of .036" and a NO-GO dimension of .028". Check with a gun smith as each firearm IS different. 3.The firing pin must stay in contact with the primer on firing. A weak hammer spring on an AR or a weak firing pin spring like on a Rem 700 bolt action will let the firing pin rebound on primer piercing when the hot gas pushes the pin backwards. 4.If the hole the pin sits in is to larger in diameter, the primer flowes back into this hole till the center of the primer separates and fall into the action or travels into the firing pin area. Bushing the firing pin hole (bolt action) will fix this.
 
Here's a better pic. The puncture was with ZQI Guardian. I know the rifle is over gassed, but now I'm wondering if headspace might be an issue. The firing pin was fine, until the pierced primer apparently flame cut it, which concluded my outing.
Click to expand...

It is not a headspace problem, it is a problem that the ammunition is too hot for your rifle. I will bet you have a nice tight barrel on your rifle, maybe the throat is cut short like a match chamber, etc, etc, etc. Who knows, you have the rifle.

If you send the rifle back, the manufacturer may ream the chamber so large that you could rent it as a Zeppelin hanger.

I am going to recommend that you reload for your rifle. I am also going to recommend you use mil spec Tula or CCI #34's in the mechanism. CCI 200 will work though I really don't know if the CCI 200 cup is as thick as the #34. I have no idea what the Turks are using in their ammunition. I am going to recommend that you use a 150 gr bullet and 42.5 grs IMR 4895, or AA2495, or H4895. Or a 168 with 41.5 grs IMR 4895/AA2495/H4895. These ought to be maximum loads in your rifle, so might cut them by a grain before you start testing. A bud of mine was having all sorts of issues with his Rock River 308, ripping rims, cases left in the chamber. His load data was several grains above my recommendations but within book values, and I was able to convince him to start at these loads. His Rock River works fine, his bolt gun works fine. His problems, like yours, is too much pressure.

If you still pierce primers at my loads, cut them by half a grain until the piercing stops. You may have an extremely tight barrel. My Kreiger barrels, they will pop a primer with these loads, I am running 40.5 grains AA4064 with a 175 because Kreiger barrels are so tight. Kreiger barrels shoot well once the load is adjusted.
 
Those primers don't look that flat to me. If over pressure were the cause I'd expect the primers to be much flatter. We all know that it's possible to have an over pressure condition without pierced primers and we also know that we can have pierced primers without an over pressure condition. Without looking at your rifle I'd suspect either an oversized firing pin hole, excessive firing pin protrusion, an undersized firing pin (or incorrect geometry) or possibly a weak hammer spring. ARs don't have a firing pin spring so don't bother with that.
 
Hmm. I'm going to call the factory and get a new firing pin. I just meticulously cleaned it and I'll try it again. There was a tiny bit of soot in the chamber. I dont handload so thats not an option for me. I've got a LaRue MBT-2s trigger in it, so I dont think its a spring issue.

I'm not too worried about precision accuracy, I just want the rifle to cycle FMJ ball without worry of it blowing up...:scrutiny: Over pressure signs from every factory load I've tried is a little disconcerting.:( So far Aussie F4 has shown the least pressure affects.
 
W.E.G. said:
I would send the entire rifle back to the factory.

They let a BUNCH of these rifles out with this problem'

ALL with the problem.

They should have to fix it, or eat the rifle.

That won't happen by you asking them for a firing pin.
Click to expand...
I thought I had recalled reading about that but just wasn't sure, not owning one I just let it go by. That being the case I would be sending the rifle back. Unfortunately you could be looking at a long turnaround.

Ron
 
I have one my barrel is tight my crono shows higher vels than advertised with 24" barrels but I've had no problems. I haven't shot a thousand rounds through it yet though
 
rifle

You said, I cleaned FP. Did you measure length, call factory for length before
u throw the rifle in the garbage.
Simplest first, such as, has this happened with any other ammo? If not,your home free. Sometimes a primer jacket can be thin. Rare,but possible.
Always check with the manufacturer before doing anything. Good luck,Lee
 
Called DPMS today and they recommend sending it back for repair. He urged me to cease firing it immediately. Was told 4-6 weeks for turn around time. While they wouldnt speculate on the phone, they didnt sound surprised by the issues. Also noticed the A2 front sight is canted and the bolt release rests against/contact the upper, making a dent/scratch (should be spaced out). Looks like I got a Friday afternoon rifle... :(
 
It's probably not truly a pierced primer.

At lower pressure, the firing pin dent might look normal. At a little higher pressure, the dent is pushed back to nearly flat. With still more pressure, the dent will invert, forming a little nipple sticking out of the primer. And with just a little more pressure, the little nipple breaks off and falls into your rifle's action.

This effect is very common in the AR15. The cure is to use the primer that the AR15 was designed for, the milspec #41. It has a thicker cup. So also does the CCI small rifle magnum primer.

So the first thing I would think about is the quality of the primers, and whether your rifle was designed along the lines of the AR15.

There is no way that copper accumulation in the barrel will increase pressure. You can fire a 338 bullet through a 308 bore with very little increase in peak pressure. Ackley performed that experiment a long time ago.

I see nothing alarming about the flatness of your primers. It is very chancy to try to gauge pressure by the amount that primers are flattened.

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Oh it definitely pierced, the mag was full of smoke, as was my face...
Click to expand...

What I meant was that the firing pin did not push itself through the primer.

The firing pin dented the primer. The pressure of the gas popped the primer dent inside out, forming a nipple. The weakest part of the nipple is a circle at the base, where the nipple popped off leaving a nice round hole.

So, yeah, there's a hole and a lot of excitement, and a little bit of speaking in a foreign language.

Good luck with getting this worked out. Sometimes its frustrating.
 
So, yeah, there's a hole and a lot of excitement, and a little bit of speaking in a foreign language.

Good luck with getting this worked out. Sometimes its frustrating.
Click to expand...

Well, we will see how DPMS treats me. I dont really get upset about lemons, EVERY company ships some turds out. I rate a company by how well they take care of said turd.;) I REALLY like the rifle, I just want it to run right and not worry about blowing the bottoms out of my mags.:p A 7.25lb AR10 feels amazing to use.
 
i have a dpms LR308B and it has a tight chamber. it wont even get close to max loads in my lee book with any powder or bullet before i start flattening primers and all the other fun stuff. but velocity's are great and faster than i expected out of the 18" barrel. very accurate gun too, shoots an average 1/2" MOA at 100 yards and well under MOA at 500 yards.

the chamber is so tight i can take a fired case out of the dpms and it will fit inside any of my .308 rifles (another 3 of them)
 
the chamber is so tight i can take a fired case out of the dpms and it will fit inside any of my .308 rifles (another 3 of them)
Click to expand...

Holy cow. If this was a more precision oriented rifle, I'd probably look into reloading, but I'd rather have this thing run loose like an AK than tight like a match rifle. It'll likely never see anything but bulk FMJ anyhow.
 
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