[Cosmoline]

I've noticed with certain hot loads older style .357's with pins on the hammers sometimes suffer from primer flowback into the space around the pin, locking the revolver up for a moment. Sometimes the flow is extreme enough to cause the center of the primer to open up. I've found this with several older revolvers in otherwise excellent condition. Any cure for the problem? Larger firing pin perhaps? Or just harder primers?

[HSMITH]

That is a PRESSURE problem, not a gun problem. Each gun is a different animal, some guns will blow primers with loads that the cases just fall out of in another gun. If you are getting primer flow you need to stop using that load in that gun and drop back at least 10%. A chronograph will prove that it is a pressure problem and not a gun problem. Velocities will surprise you.

[P95Carry]

I concur with H totally. I agree that primer flow can be more noticeable with fixed firing pin models but only marginally. A degree of primer flattening with hotter loads I don't regard as serious but this described flow -- BAD!

Use reduced loads ... better all round. Factory .357's should be Ok - they are these days quite mild IMO but homeload ''hotties'' ... careful!

[JNewell]

John Linebaugh has said (http://www.sixgunner.com/linebaugh/gunnotes.htm) that it's unusual to see the kind of signs of high pressure that we are accumstomed to seeing in bottlenecked cases in straight wall pistol/revolver cases -- like flattened primers (see quote below). I think he's written somewhere else that if you do see conventional signs of high pressure, then pressure is usually more than just a little high but sky high. FWIW...

Straight cases handle pressure differently than bottle-neck cartridges and often show no excessive pressure signs. We have blown a few guns up here, on purpose, and in all instances upon recovery of the cylinder fragments and case remains, the primer has shown normal pressure. Pressures in these instances have run from 70,000 to over 100,000 psi in our estimation. Do not depend on case pressure signs for danger signs in a sixgun. In most cases the first sign of high pressure you will have, other than excessive recoil and blast, is a bulged cylinder or cracked bolt notch.

[Cosmoline]

Well I'd go along with that, but these aren't handloads. The signs are coming from Bufallo Bore's 180 grain hardcast .357's in my otherwise flawless Model 13. I had no problems with the first batch of 170 grainers from B. Bore, but the box of 180 grains I fired this weekend was all busted and flattened primers. I figured they must have been soft primers, as the pressures on this load are not supposed to be too high for steel revolvers.

Also, I have shot similar hardcast 200 grain corbons with no primer problems or pressure signs from this revolver.

:confused:

[Standing Wolf]

Well I'd go along with that, but these aren't handloads.

Hand-loaders don't have a monopoly on exceeding safe pressure levels.

[Cosmoline]

But Buffalo Bore .357 loads are all within SAAMI specs.

AH! Now this is interesting. Just found this on line in a test of this very ammo:

"For some reason, likely either softer primer cups or higher pressure, the Buffalo Bore ammo, tended to flow primers somewhat around the firing pin, and this occasionally tied the revolver up. Since neither of two newer long guns showed any similar problems, we chalk this up to a failing of the gun. Nonetheless, we wouldn’t use this gun with this ammo."

http://www.gunblast.com/MilesFortis-AKChurch_BuffaloBore.htm

Now, since I'm NOT getting signs with equally hot Corbon hardcast loads with this revolver, soft primers remain a possibility.

In the mean time, no more Buf Bore hardcast for this revolver. I'll contact the company with my issues and see if they are working on a fix.

[caseydog]

Here's a .44 in the 'Smithing section of the S&W Forum thats having the same issues with factory ammo. I've heard the name Nelson Ford before and if he doesn't have an answer for the guy I sure don't.

http://www.smith-wessonforum.com/ubb/Forum18/HTML/002239.html

My suspect would be the pin bushing ( mysterious part # 30 in this guys description) but I would want to check the throat sizes before I told him to have it replaced.

Ray

[Cosmoline]

I'll run some more tests and see if this pin is causing flow problems with other .357's. I haven't had any freeze-ups, but then again I haven't really been looking at the primers much. Other than this batch, function has been 100% with the M-13. The pin IS quite old and very rounded. It may simply be a matter of getting a new one with a flatter head.

[HSMITH]

Buffalo Bore ammo is right at the top of the SAAMI specs, if your gun has tight throats or a small alignment issue, or any other of dozens of possible causes, that is more than enough to blow primers on a load that is plenty safe in another gun.

Guns are individuals, no two exactly the same, so we can't expect them to act the same when fed ammo from the same box.

Have you looked for barrel crush under the frame threads? Lots of Smiths show this and with the length, bearing surface, and hardness of the BB cast bullets it can be the cause of high pressure. This and small throats are the most likely causes.

[Cosmoline]

FYI, here's the response from B. Bore. This is what I suspected. The flow was just too extreme to be merely a revolver problem.

That's true about AK and ammo, sadly.


-----
Thanks for the email.

The problem you are experiencing is both a large firing pin hole and too soft a primer. You are using some of our very first run 357 ammo--the same batch that was used in the Gun Blast article you cited. On all of our subsequent "runs" we have used a much harder primer and this has alleviated
the problem entirely.

If you were in a place that I could ship ammo to, I would send you a complimentary box with the new harder primer, but you are in a place that I can not simply ship one box too. Getting ammo to AK has to be done by barge and requires a large shipment.


--
Dear Buffalo Bore,

I tried out a batch of your new .357 180 grain hardcast in my Model 13 Smith & Wesson this weekend. I was very pleased with the pinpoint accuracy and impressive power of the loads. However, I noticed consistent primer flow around the pin and several burst primers resulting in temporarily locked
cylinders. No other pressure signs were present, and no damage to the revolver resulted. Given that the revolver shoots 200 and 180 grain hardcast loads from Corbon and other makers with no problems, I suspected a primer problem or a problem with my firing pin in relation to these particular primers. I do not suspect excess pressure per se.

In examining the issue further, I found this note in a product review of the exact same ammo:

"For some reason, likely either softer primer cups or higher pressure, the Buffalo Bore ammo, tended to flow primers somewhat around the firing pin, and this occasionally tied the revolver up. Since neither of two newer long guns showed any similar problems, we chalk this up to a failing of the gun.
Nonetheless, we wouldn’t use this gun with this ammo."

http://www.gunblast.com/MilesFortis...BuffaloBore.htm

For the time being I've stopped using the Buf. Bore loads, but I'd love to get a resolution of this issue. Is the problem soft primers, or simply overlarge firing pin holes in old revolvers?