Pierced primers - what is causing this?

[glock24]

I had my first encounter with what I believe are pierced primers today with my 223 Remington. Out of 69 shots today, I had 3 or 4 of them. They all seemed to come during the first 20 shots or so. The outside temp was only 80-85F.

- Factory Remmy 700 action, trued by Black Ops Precision, but I don't believe the firing pin was bushed
- Once-fired Lapua brass
- Federal small rifle match primers
- 80.5g Bergers
- 24.7g 8208 XBR

I know some of you guys are going to immediately zero in on the fact that 24.7g is above any published load data, but know that I have my bullets seated way up in the neck. I've also previously tested powder charges beyond this, and I didn't start seeing pressure until 25.3 grains. That 25.3g, I started seeing ejector marks, blown primers, and a sticky bolt. This is why I backed it off to 24.7g in the first place. At 24.7g I had no over-pressure indications. The rifle cycled fine. If I hadn't noticed these particular primers when picking up my brass, I wouldn't have known it any other way.

Any other thoughts, or am I just fooling myself?

Pierced primers


Normal primers (same day)


Close-up of the bolt face (black Cerakote wearing off)

 

[rduckwor]

I can't really tell from the pix. They do look deep compared to the others. However, I don't see corresponding evidence on the bolt face. I do see the typical Remington cratered primer from a loose firing pin channel.

I can't speak for Fed rifle primers, but their pistol primers are butter soft. Maybe grab some CCI SR primers and see what gives?

Good luck,

 

[BuzzBoss915]

I'm old school. No matter what your safe load was, the other day, today you have a hot load. Now, exactly why, other than too much pressure, I don't know? It could be that those particular loads had too much powder in them, or maybe the case capacity is abnormally less, maybe a different lot #? Chances are that you are pushing the limits, and the prudent handloader will back off at least a half grain, maybe more to cover all eventualities, ambient temperature, too fast cycling, etc.? The difference between 25.3 and 24.7 ain't very much, in that size case. Was all the previous shooting done with fireforming virgin brass and a load of 25.3 gr.?

You are lucky that you didn't damage the bolt face but you will, (eventually) unless you back off your charge. Performance is important but not at the expense of reliability and pierced primers, even 5% is not acceptable. You want zero. Changing primers is probably a waste of time without reducing your load, no offense intended, for the suggestion.

Bottom line, too hot; back off and live with safe reliable performance. It doesn't matter that you got away with it before, this is a warning, a caution; pay attention to your evidence.

That's all I can come up with? BB

edit: I knew I forgot a possibility. Could be setting the shoulder back too far, creating excessive headspace. The case jumps forward, then backward and the primer is pierced on the rebound?

 

[armorpl8chikn]

Your "normal" primers don't look normal at all. Pretty heavy cratering from what I can see. BACK OFF THE LOAD. Primers look a bit flat too. Lapua brass tends to be rather tough, and in that vein you better pay attention to your primers. It is true you can switch primers, and I would. I had a load with 80gr bullets using CCI400 primers that exhibited a bit too much cratering to suit me. Switched to CCI450 primers and the load was fine. All federal primers are soft. They also tend to ruin primer pockets prematurely, probly cause they are a bit soft.

 

[korykhunter]

I would try backing the load down a bit and if you still have that much cratering have the bolt sleeved.

 

[Graham]

It's hard to tell pressures on a .223 just from looking at the primers. I load until the primers do that, then back off half a grain. Maybe your pressures are higher that you thought they would be because you are seating the bullets deeper than usual in the case.

With the 80s, try Varget and RE15.

 

[BoilerUP]

I seem to recall Pipes, er, 223AI runs 24.4gr XBR in his 223 with 82gr Bergers.

I run 24.8gr XBR in my 223AI with Lapua brass and 80gr A-Max.

 

[Clark]

The pressure a primer can take is dependent on:
1) the primer cup thickness
2) the firing pin to firing pin hole fit
3) the firing pin mass

Here is a pic of my 1901 Winchester 92 with eroded [from pierced primers] firing pin to firing pin hole fit. The most pressure with the thickest primer cup [CCI 450 small rifle magnum] is 28,000 psi. And that is right on the hairy edge. I would like to run 40,000 psi, but the firing pin fit will not allow me to do that.

Here is a pic of my Ruger #1V running up to 100,000 psi in 223.
The .223 brass is registered at 55, 000 psi and has long life at 75,000 psi, but 100,000 psi will enlarge the primer pockets.
Notice how the standard primer [WSR] did not pierce. That indicates good firing pin to firing pin hole fit.

Here is a pic of my rebarreled 1938 Turkish Mauser with some 7.62x51mm brass at ~ 100,000 psi.
The brass is registered at 60,000 psi and has long life up to 67,000 psi, but the primer pocket expands at 100,000 psi.
Notice how the standard primer [WLR] did not pierce. That indicates good firing pin to firing pin hole fit.

There are cartridges that the primer is the weak link.
6mmBR has a small Boxer primer pocket in an 1889 Mauser case head.
To go higher in pressure, ~ 85,000 psi, one can get the firing pin bushed.
This improves the firing pin to firing pin hole fit.

Gre-Tan offers this service.

Maybe you need that service, not for super high pressures, just to do normal pressures.

 

[Absolution]

My thoughts go as. Sharp firing heavy firing pin spring. Which the only problem is sharp firing pin. The heavy spring shouldn't matter. I'd try and use some harder primers and or back off your loads

 

[damoncali]

Hard to tell from the pictures, but your normal primers look slightly flattened. Your load is most likely too hot (as indicated by the manuals). Cratering is an unreliable indicator that can sometimes be pinned on the gun rather than the load, but its presence backs up the "too hot" theory.

 

[cav has been]

CRAP!!! Clark those pics. made me mucho scaredid and I'm two states away!
OP,
#1 excessive head space/lube on cases
#2 soft primers ( try 450's )
#3 loose tolerance on firing pin
#4 weak main spring
#5 A combination of any or all of the above

 

[Graham]

Whenever someone posts a pic of a blown primer people line-up to say that the cause must be a sharp firing pin or a soft primer cup. The correct answer has nothing to do with duller firing pins and harder primers.

 

[damoncali]

Whenever someone posts a pic of a blown primer people line-up to say that the cause must be a sharp firing pin or a soft primer cup. The correct answer has nothing to do with duller firing pins and harder primers.

Sure it does. It's just not the whole answer - there are lots of things that contribute, like pressure, improper headspace, firing pin/hole clearance, primer material, firing pin spring strength, and probably a few more things.

 

[rjacobs]

Have you recently changed powder lots?

There was a thread on M4C where a guy was running a very similar combination(77g SMK's and Noslers, slightly above max 8208XBR, not sure what primers, Rem 700) and all the sudden after a few thousand rounds(he had like 16lbs of the powder lot he started with I think) he switched lots and with the same load he was blowing primers and his velocities were way high when he shot over the chrono.

He backed down I think .5, gave up a little velocity, accuracy stayed good, but the load was safe between lots.

 

[Clark]

At 2.26" OAL, Quick Load thinks that load is 91 kpsi.
At 2.66" QL thinks it is 63 kpsi.

So I would need to know the OAL and if the bullet is touching the lands.

 

[Absolution]

Sure it does. It's just not the whole answer - there are lots of things that contribute, like pressure, improper headspace, firing pin/hole clearance, primer material, firing pin spring strength, and probably a few more things.

+1. Yes his loads are high but at same time I see cratering of primer when I go to benchrest competions to watch. Its when I start seeing flattened primers I say no

 

[Absolution]

I just got my my computer instead of my iphone i can see the primers better. You are very close to flattening primers they are starting to wave ( a second crater ) Lets hope you don't go shooting in hot weather soon or you are looking for an accident.

 

[Fuzzball]

Whenever someone posts a pic of a blown primer people line-up to say that the cause must be a sharp firing pin or a soft primer cup. The correct answer has nothing to do with duller firing pins and harder primers.

And the value of your post is ....?

Saying you've had "no signs" of pressure in your overloads is kidding yourself; cratering IS an excessive pressure sign OR a poor pin/hole fit or a weak spring sign, or all of them sign.

"Flat" primers are most often a sign of setting bottle neck case shoulders back too far.


" ...know that I have my bullets seated way up in the neck"

I don't know if that means you're seating long or short OALs but I can tell you that seating towards the lands runs pressures UP.

 

[Graham]

And the value of your post is ....?

Perhaps two cents more than a few of the above.

 

[shoot4fun]

Just because your load had worked fine really is no justification. I recently worked up a load for my 243 using Lapua brass, FGMM primers, 115 DTAC (naked) and H4350. The OCW went well and no over pressure was evidenced so I choose the best candidate. Subsequent range time showed it to be an extremely accurate load; again no pressure. I took this rig to an F Class match with visions of trophies and records dancing in my head only to have things go all wrong. Suddenly (and without warning) pressure spiked, primers blew (yes I was a dumb ass for keeping it running after the first one) and ejector marks were everywhere. I still don't know what happened and have since fired a few more rounds of the same load without issue. Fortunately the gun was not hurt and neither was I. But now it is back to the drawing board on a solid load for the rifle and into the trash for several pieces of once fired Lapua brass. OK, so it took a while to get to the point but I think the OP should go down the same road.

 

[glock24]

At 2.26" OAL, Quick Load thinks that load is 91 kpsi.
At 2.66" QL thinks it is 63 kpsi.

So I would need to know the OAL and if the bullet is touching the lands.

Thanks for the info, Clark. My loads are 2.46", and .030" off the lands. It looks like QL would predict some serious pressure at that seating depth.

Thanks to the rest of you. I was hoping I was justified with my load because of the lack of ejector and extractor marks. Apparently not. These primer clues seem to be telling me I'm pushing things too hard. I did in fact switch lots of powder, and I'm also not 100% sure I didn't get any bullet setback, as I was mag-feeding these rounds. It looks like I need a little more safety margin for these errors.

I just reviewed my load data, and I'm switching back to the previous accuracy node for now. I'm also toying with the idea of bushing my firing pin just for piece of mind.

Thanks again

 

[rjacobs]

I did in fact switch lots of powder

Here is the thread I was referencing from M4C where he narrowed it down to a lot variation:
8208 XBR Lot Variations. - M4Carbine.net Forums

 

[glock24]

Here is the thread I was referencing from M4C where he narrowed it down to a lot variation:
8208 XBR Lot Variations. - M4Carbine.net Forums

Thanks. I was really hoping I need not worry about lot-to-lot variation with this powder. Oh well.

 

[rjacobs]

Thanks. I was really hoping I need not worry about lot-to-lot variation with this powder. Oh well.

I dont think that you need to. The guy in the thread was running lower than you and was showing pressure signs when switching lots. I would simply back the charge off and go from there. I would go down to the next OCW node and call it a day. You are giving up some velocity, but for a good reason.

 

[former naval person]

Federal primers. Go CCI. JMHO

 

[Rprecision]

Hard to tell from the pictures, but your normal primers look slightly flattened. Your load is most likely too hot (as indicated by the manuals). Cratering is an unreliable indicator that can sometimes be pinned on the gun rather than the load, but its presence backs up the "too hot" theory.

Solid advise

 

[Josh Smith]

Hello,

I've just re-found this forum.

I agree with those who say you're running too hot. Back off and find the next node down -- ladder test, in other words.

I don't load near max and don't understand why some do. If I want more performance, I just grab the next caliber up. But that's not a criticism; to each his own.

I just don't want to see you, or anyone, hurt. Work within the cartridge's safe limits, preferably in mid-range velocity. It'll save your barrel, too.

If you want more velocity, you might play with moly coating. It reduces friction and could make those loads safe, though I don't endorse the practice. I don't like the stuff personally, but some swear by it. I have some KG-12 Moly Bore Treatment I've not played with yet and may not. As well, Militec-1 does work for reducing friction, but it's limited to lubing. Don't count on it to protect.

I personally would back down the charge to the next node lower, as I said.

Regards,

Josh