[sam7a1]

It looks like the primers are being pushed into the firing pin hole.

I havent had any primers pop out completely, yet.

The first pic is before i sent in my bolt, the second pic is after.

It looks like the "fix" made the problem worse.

They stick out pretty far now, so much so that when you set them on end they are very wobbly

Notice the 4 different head stamps in the 2nd pic, 2 are radway green but 2 different dates.

We shot 3 AR-15's today and all their brass looked fine with normal primer indents. Is this just the way XCR's are or what?

 

[TerraShrewsbury]

The XCR will typically cause cratering, yes. I don't know why it's doing it more now, but as long as you aren't punching primers, I would say it's fine. Keep an eye on your brass.

Actually, the first picture shows perfectly normal primers after being through an XCR. Were no primers being punched when you sent the bolt in the first time around?

 

[sam7a1]

No just being extruded.

I haven't seen any pierced primers.

 

[charliea]

I'm just wondering, out loud, if maybe the hammer has too much mass. Possibly the firing pin, because of it, isn't retracting fast enough and the primer is flowing around it. Robinson has apparently gone the route of heavier hammers to take care of light strikes. Often, a better cure is a lighter hammer. Skeletonized hammers accelerate faster, hit with more energy, and have less mass. Could be the way to go. Again, just thinking.

 

[TerraShrewsbury]

Actually, we ended up going with heavier hammer springs. We had better results with those.

 

[tk]

I just got my bolt back from terra for the same issue, and I'm wondering if it's not a little more complicated than we've assumed in the past. Here's why....

I put about 1,000 rounds through mine of mixed cheap ammo (although no wolf) with no ill affects: no jamming, no problems with primers, nothing.

The I started reloading mil-spec (crimped) brass I picked up off the ground at my range. So far, so good until I got hold of some Lake City cases. The Lake City cases extruded, cratered and even pierced. Haven't tried out the bolt since I got it back (THANKS TERRA!). They all showed signs of excess pressure -- none of the other cases did.

What's different about the LC cases? A thicker cross-section? Smaller capacity? These issues could lead to higher pressure.

I also wonder whether there is a dimensional difference in the cases. There can be significant differences between the military and civilian versions of cartridges and the 5.56/.223 is a good example of that. The 5.56 cartridge can be loaded to significantly higher pressures and still be within mil spec. I beleve the oppsite s true for the .308/7.62.

Anyone have any thoughts?

tk

 

[TerraShrewsbury]

well, the softer the primer, the less fond of it the XCR is. When you shoot wolf ammo, you'll notice there is almost no cratering at all. But remington or american eagle will have crater rings, and anything softer than that...

 

[aziator]

I may be wrong but I think that military cases are built a little thicker (we are talking thousandths of an inch) to provide for more strength to handle those higher pressures. I think in theory you will loose some case capacity, again not much. If you are loading commercial brass on the edge of being hot and use that same recipe for .mil brass you may run into higher pressures.

me personally, I shoot mostly mil brass. I haven't seen any wierd primer issues with my gun. yes they crater a little, they have been doing that from day one. They do it more on soft primers. Me, I like the idea of getting a good strike on the primer. As long as it isn't punching through all should be good.

ON EDIT, I load mostly using CCI.

 

[charliea]

On the bright side, it's easy to separate your brass at the range. Nobody else has those funky primers. It's not a pressure issue. I'm loading LC brass with CCI41 primers, but I'm a full grain off the published max with Accurate 2230, and the chrono affirms I'm where I oughta be. As we know, when the round ignites the primer is pushed out of the pocket, back against the bolt face. The brass is then pushed back, reseating the primer. As the primer comes back it should push the firing pin out of the way. Normally this increases the depth of the dimple, but not much else. I think what's happening here is the firing pin is not getting out of the way in time, due either to an excessively strong spring, or interference from the hammer. I'm not an engineer though, and wouldn't stay in a Holiday Inn on a bet, so who knows?

 

[Bravo]

Az, +1.

OK, now if you research into primer cratering, you'll see that it's a pressure issue, but not necessarily a pressure issue the way you're thinking.

Firing pin pressure has a LOT to do with it, as does the bolt face.

Think of this: how 'softly' does a pistol hammer smack the primer with relation to the striker on a Winchester model 70?

It's not a matter of energetics required to pop the primer - a soft pistol hammer strike will ignite a rifle primer easily. So why make those danged Remmie 700 and Winchester 70 striker springs SOOOOO hard?

Much of primer cratering is the flow from the primer around the striker tip. Hold the tip in place harder and longer, you get less flow.

Another big contributor is the fitting of the striker to the hole in the bolt face. Mate those two up nicely, you get very minimal cratering. Of course, that's the job of a custom 'smith.........

If the cratering and such is due to excessive chamber pressure, you'll notice primer flattening as well. In my younger (read that as "less cautious in experimentation") I didn't mind loading rounds up to the point there wouldn't be a discernable roundness to the edge of the primer. Like P.O. Ackley, if I said it was safe, it was. 1/10th grain more powder and there'd be a crater in the ground where you were firing though LOL!

And, as Az said, primer cup hardness ;-) I'm gonna buy some Wolf primers just to see if they're as good as advertised, and as hard as CCI.

FWIW, I switched from CCI to Winchester many years ago. Yes, they're not as tough, but they're close. MUCH better than Remmie or Federal IMO.

 

[charliea]

Gotta wonder. With 44mag handgun I load 15K practice rounds and 40K bombs. The primers look about the same, and don't flow one way or the other. Same pin, same spring. I guess there's a big difference between straight-walled pistol cases (which I at least know a little about) and bottleneck rifle (which I know nothing about, except I've learned that case preparation is best left to SE Asian slave labor).

 

[Guest]

I think with this new spring loaded firing pin setup we are looking at a "firing pin dwell time" thing. as mentioned by bravo above, the large pin and FP hole are also contributing. when I first saw this, my thought was that the firing pin hole was jsut too big and had too much space around it. that may be the case still.

 

[tk]

Thanks for the comments. I've been using federal primers; if they're soft, they may be part of the issue. Course, I've still got about 2,000 to get rid of...

I also like 2230 for 5.56, although I loaded the rounds in question with Varget.

BTW: The LC cases weren't just extruded -- several were pierced, and one had a little divot from a primer welded onto the primer face.

tk

 

[Bravo]

Yup, the cookie cutter thing.

Too soft of a primer, coupled with too much pressure.

People love Federal primers - I always wonder why.

If you check out the phase of styphnate that they patented, it's about the lousiest. Makes sense though, as Winchester and Remington had already gotten theirs first (Federal got left-overs).

 

[tk]

I've been using them because they were a couple of bucks cheaper per box from my local reloading supplier. I'll try another brand.

thanks for the guidance

tk

 

[charliea]

My handguns all have aftermarket springs and lightened actions. I load with Federals exclusively, for them. I've been told that for semi- rifles, however, you want the hardest primers you can find. That's why I'm using the CCI41's.

 

[shortfal]

I just about got rid of the cookie cut primers by putting a lighter spring on the firing pin such that a chambered but unfired round shows just a tiny firing pin mark that is not uncommon on many semi auto rifles. I think the idea of firing pin dwell time is the answer (more not less). The FP needs to be in the primer indent during the time of high pressure. Otherwise the indent is unsupported and prone to being flattened and or reversed and pushed into the FP hole in the bolt. Probably a combination of (slightly) lighter FP spring, a heavier hammer spring and a heavier hammer would make the XCR behave like the other 15 or so 5.56 rifles I have that do not extrude or cookie cut primers and do not have their firing pin holes chamfered.
Take the above as FWIW, or food for thought as I often seek complex solutions to simple problems.
DO NOT willy nilly fool with the RA installed FP spring! TO LIGHT a spring could cause an out of battery firing with weapon destruction and or personal injury.
Pete

 

[sam7a1]

So whats the consensus on this, is it going to cause a problem?

As for the lighter hammer spring, i had one in there but i would get failures to fire in 50% of the rounds. Sometimes rechambering the round would set it off but sometimes not. The primers showed very light hits, but they always go off when i put these rounds in a AR-15.

I still get light strikes with the stock spring but only maybe 2 out every 30 rounds will do it. Of course it may be due to the fact i only have 600-700 rounds through the gun also.

 

[charliea]

Two out of 30 wouldn't be acceptable to me. Actually two out of 3,000 isn't, either. I got an XCR because it's said to be about the most reliable rifle this side of an AK. I had some light strikes in my first hundred rounds, but if that continues it's time for a fix. I might actually need this thing to go "bang" some day. Usually when you need that you need it really, really bad. "Click" doesn't cut it.

 

[tk]

I think I have had one FTF (with a factory round) and it looked like a bad round -- simply didn't fire after several strikes. I've not had a FTF with my handloads.

Went to the range yesterday afternoon; didn't get a chance to to a lot of shooting because it had been raining all day and shooting stops at sundown.

Could only recover a small part of my brass (the rest was lost in the grass), but I don't see any further problems. I did have a couple of LC cases in there, and they showed no signs of cratering. There's the faintest ring around one Winchester case, but it's almost imperceptible.

I certainly don't think that this is an issue that compromises reliability.

tk