Cracked Forcing Cones

[jimmyj]

Hi:
In Model 19s using 125 grain .357 JHP ammo has causing forcing cones to crack/split in "K" Frames. Has this happened in "K" Frame .38spl revolvers using 125 grain JHP .38spl ammo ?
Jimmy

 

[MKT]

I can't answer your question but I can tell you that one can put enough rounds of .38 wadcutter through a competition barrel to split a forcing cone. Can't tell you the count but it was in the 100s of thousands.

 

[Oldiron]

Jimmy, don't know if they were using JHPs but I bought a pre 10 with a big chunk out of the cone. Wondered how in the ---- someone did that until I got it home and found the tell-tell sign of someone beating on the crane with a brass drift. Apparently someone had squibed one in the barrrel and drove it out the side of the barrel instead of back down the case. Could have been a 125 JHP????? I just done know. All I know is that I have a $75 truck gun including the replacement barrel.
Larry

 

[scooter123]

Jimmy, that 125 grain 357 Magnum will normally generate about 600 ft.lbs. of muzzle energy out of a 4 inch barrel. A typical 125 grain 38 +P will generate pretty close to 248 ft.lbs. of muzzle energy. Step down to 38 spl. and your in the 200 ft.lbs. range for energy. I think that you can find your answer in these numbers, the 38 +p and 38 spl. are weak enough that I wouldn't be too concerned about cracking the forcing cone.

 

[rwsmith]

No problem

A model 19 should eat .38 +Ps like popcorn. I had a model 10 that I shot a variety of stuff through for years (like 125 gr.+P) and it was like new when I traded it. Full load .357 magnums can't be taken in a 19 continuously, though. I'm glad I got my 686 because I find that I LIKE big loads that go boom.

 

[moosedog]

The secret is to never get a build up of too much lead on your forcing cone and then try to run high pressure JHPs thru it.

 

[dfariswheel]

The secret is to never get a build up of too much lead on your forcing cone and then try to run high pressure JHPs thru it.

Or carbon or copper fouling.
Even guns fired only with jacketed bullets should have the forcing cone cleaned with the Lewis Lead Remover cone cleaning head to remove the build up of carbon and copper jacket fouling.

What seems to happen with guns fired with the hot 125 grain Magnum loads is basically metal fatigue caused by the super-heated abrasive gas and the fast bullet hammering the cone.
The .38 Special or the +P loads just don't generate that level of heat or impact.

 

[Snapping Twig]

Maybe I can offer some help too.

When slow powders are used in magnum rounds, there's a need for the powder to fully combust before the bullet jumps the cylinder/cone gap.

If the powder is not yet burned and still has mass, that burning semi plasma can sandblast and scale the forcing cone, aging it and removing material. You can actually see a scale like pattern in the metal with proper magnification.

The short 125g bullets were not long enough to allow the magnum charge to burn completely before the bullet transited the cylinder gap allowing gas to go around them and this led to many failures.

It is also said that due to the higher speed and the short length of the light bullet, in addition to the above mentioned issues, the unguided bullet would have a moment of time to misalign and strike the lower portion of the forcing cone. Longer bullets are still in the cylinder completely as they enter the forcing cone, but short light ones are not.

Faster powders are typically used for 38's, so in truth I wouldn't worry about light bullets in 38 Spl. for a K frame.

Shoot them in good health.

 

[mstuhr]

Yes we can

Hi Jimmy,
I don't know if it helps or not but I second what MKT says. A guy can wreck one with enough light loads.
Thanks
Mike

 

[NFrameFred]

A comparison that many don't consider but should is that this area of the barrel extends past the frame unsupported/enclosed and high pressure rounds and/or fouling build up causes it to flex/expand slightly as it accepts the slug and starts it on it's journey.

Just as over-expanding/over-working much softer brass case mouths when re-loading will cause them to prematurely split, the same concept applies here. The forcing cone is overworked, eventually causing it to fail if not properly maintained and correct pressure loads used.

38 specials are much lower pressure rounds, but many thousands of rounds through an unsupported forcing cone allowed to retain lead and copper fouling could do the same. I've seen three magnums split like that and heard of a gun used for PPC with 38 target loads doing it, but didn't see that one personally.

 

[poordevil]

There are many very knowledgeable folks here. But it looks like non have actual seen or worse yet, experienced a split forcing cone themselves.

I have been shooting S&W handguns for over 40 years and I use 125 gr Mags out of my 4" nickel 19 and 6" 66 and 3 "13. All are GTG. Unless you shoot nothing but 125 mags all day, every day year after year, I would not worry about it.

 

[dfariswheel]

I've seen a few cracked cones.
In every case where the owner was available to be questioned and would admit it, the cause was stupidly over-pressure hot loads.

I've never seen or heard of a lead bullet target revolver with a cracked cone.
Back in those days, the revolver target match shooters were very serious people and everyone took perfect care of his guns.
All of them I ever saw had a Lewis kit in his shooting gear.

 

[mstuhr]

It happens

There are many very knowledgeable folks here. But it looks like non have actual seen or worse yet, experienced a split forcing cone themselves.

I did, on a Clark built PPC gun. Steady diet of light loads.
Thanks
Mike

 

[NFrameFred]

There are many very knowledgeable folks here. But it looks like non(e) >sic< have actual seen or worse yet, experienced a split forcing cone themselves.

I have been shooting S&W handguns for over 40 years and I use 125 gr Mags out of my 4" nickel 19 and 6" 66 and 3 "13. All are GTG. Unless you shoot nothing but 125 mags all day, every day year after year, I would not worry about it.

I've seen three magnums split like that and heard of a gun used for PPC with 38 target loads doing it, but didn't see that one personally.

Keeping the gun clean is critical. There is a school of thought that this phenomenon is confined to a particular batch of barrels but I've never seen anything definitive on that. Several members (including me) have openly stated we have seen this, so to say that "none have seen or experienced a cracked forcing cone" is a disingenuous statement.

 

[dewey]

Some good info to ponder....
Glad I mostly shoot .44SPLs in N frame guns...

 

[rwsmith]

Great advice

The secret is to never get a build up of too much lead on your forcing cone and then try to run high pressure JHPs thru it.

I think this is a key piece of advice. I've noticed that even in the course of one range visit my gun can get gunky depending on what I'm shooting. I'm going to pay special attention to the forcing cone because I want to keep my gun a long time. THANKS!

 

[poordevil]

Keeping the gun clean is critical. There is a school of thought that this phenomenon is confined to a particular batch of barrels but I've never seen anything definitive on that. Several members (including me) have openly stated we have seen this, so to say that "none have seen or experienced a cracked forcing cone" is a disingenuous statement.

Sorry I did not hang on your every word there Fred. So we have one fellow who has seen 3 and maybe hundreds of others who have never seen it while it occurred or even laid eyes on one after the fact, such as me. I never said it was impossible. Heck, there is a thread somewhere else here about 2 fairly new m-67's losing their barrels during a cop class. Things happen, however I believe the forcing cone issue is over stated. JMHO.

 

[Iggy]

I always get the shivers when I read about some guy telling folks to shoot copper jacketed bullets to clean out the lead and copper fouling bullets at the end of a shooting session...