Cratered/bulged primers, who's getting them?

[funflyer]

Just about all the primers from the cases fired through my R51 have the bulge with the crater flow around the firing pin. Reading dozens of threads on several different forums points to all kinds of causes, from headspace, firing pin hole too large, over-pressure, firing pin design and so-on. One writeup suggested the Pedersen design contributes to this by nature of a non-locking breech block that's free to move as the firing pin strikes the primer. Seems plausible.

So are there enough of us having primer anomalies to consider them normal with the R51, or are there some that never have the issue?

[1911SHOOTER]

Todd,
     You need to get with Kirk on that issue.   He seems pretty sharp on that stuff.
It could be a head space issue, but that is mostly above my pay grade
Blackie

[R51Fan2017]

Todd,

I have been having the same issue, from round 1. I discounted it as being normal after I examining all of my cases. Never had a problem, or felt like the cartridges were overloaded. Maybe a headspace issue, but I have yet to have a serious failure yet, so I am not overly concerned about it. Should I be?? Who knows. Just saying.

Sean

[Zenshot]

I have seen this with several 9mm and 380acp handguns.  I wouldn't worry about it unless you are handloading some very hot rounds.

[1911SHOOTER]

Guys,
Next time I go shooting, (tomorrow)  I will examine my brass.
Blackie

[funflyer]

Blackie, let us know which ammo you're using also. I've noticed that the primers from the Winchester NATO spec stuff look much better than just about all the others, including the Winchester red label. Not sure why, different primers maybe?

[1911SHOOTER]

Todd,
     As i have stated many times, I am impartial to brands of 9MM.   My Charlotte
R51 (Blackie) eats anything.  My Huntsville R51, (Smokey)   Is working well too.
Tomorrow, I will try Winchester USA Forged, steel case.  Among others.
My ammo box is mixed.  I grab a bunch of ammo out of the box, and take it to the
range.   If a pistol does not like it, the pistol goes into the safe as a safe queen.
Magazines, a different story,  they are numbered and logged.  All pistols.
Blackie

 

[funflyer]

Here's a few for comparison. Most are like this except for the Winchester NATO which are half this bad.

[R51Fan2017]

Here's a few for comparison. Most are like this except for the Winchester NATO which are half this bad.

Todd,

I used Federal in my tests and they all (150 rounds) looked like that. I am beginning to think this is normal for this pistol.

Sean

[Engineerpower]

I don't see any other signs of excessive pressure, looks to me that it's just primer flow into the firing pin channel under normal chamber pressure. If you can, measure your pin channel; mine is 0.078".

[lklawson]

The three different R51's I've had all do this.  The Gen 1 was the worst.  It would expand the crater so much that the empty brass would not sit level on it's base after firing.

The two Gen 2's do it but not nearly so bad.

Peace favor your sword,
Kirk

[funflyer]

I don't see any other signs of excessive pressure, looks to me that it's just primer flow into the firing pin channel under normal chamber pressure. If you can, measure your pin channel; mine is 0.078".

My FP channel measures .075"  however,  some of the primer bulges are .015" to .020" larger with witness marks from the smaller pin channel. This can only mean the case is not in contact with the breech face during firing. I'm going to measure the headspace today and see where we're at. I'll post more info later along with pics.

The three different R51's I've had all do this.  The Gen 1 was the worst.  It would expand the crater so much that the empty brass would not sit level on it's base after firing.

The two Gen 2's do it but not nearly so bad.

Peace favor your sword,
Kirk

Kirk, any chance you still have a gen1? It would be interesting to compare and see the differences between the two.

[lklawson]

Kirk, any chance you still have a gen1? It would be interesting to compare and see the differences between the two.

I traded it back to Remington for a 1911R1.  A dollar-value trade up. 

Peace favor your sword,
Kirk

[funflyer]

Okay, now things are starting to make sense as to why this is happening.

First, the headspace is within spec @ .760", not terrible, but I'd rather see it closer to the minimum since most cases are are in the .745" to .749" range.

Now for the first  issue. The extractor makes contact with the front of the extractor groove to the point it's keeping the round from contacting the breech face, not good. Using a dowel down the barrel, I can feel the resistance when I try to seat the case up to the breech. Best I can tell it seems to be allowing a gap of .005" to .007". Take a look at the pic and you can see the mark made by the extractor when the round was fired or possibly when it was fed under the extractor, proof the extractor is causing an issue. There seems to be plenty of material at the hook so I may mod the extractor or buy another to mod.

Next comes the barrel, or chamber to be exact. Damn thing's tight. Starts at .390" near the breech face and is not concentric inward near the flange. It's runs .382" to 378" in spots. I ordered a new Ebay barrel to see is the originals are in spec but if they're not, I'll have to have a gunsmith clean them up with a finish reamer. In the pic below, you can see the obvious striations on the case from when it was extracted from a tight chamber.

[1911SHOOTER]

Funflyer,
     This stuff needs to be going to Big Green.   We are spinning our wheels
here.   Actually, Big Green needs to be liaising with us on these issues.
But they will undoubtedly say we are amateurs.
Blackie