Jacket separation in Montana Gold 158grain JHP 357

[lunker 274]

I was shooting my Rossi 92 357 lever gun in the Central Jersey pits yesterday with a few forum members. I was using Montana Gold 158 JHP bullets, CCI small magnum primers, and blue dot powder. One of the shots sounded muffled, but I saw the water bottle I aimed at explode. Taking the cautious approach, as suggested by me fellow shooters who heard the same thing, I ejected all the live rounds and looked through the barrel. There was an obstruction. I stuck my aluminum squib rob down the muzzle and look what popped out the breech. The bullet must have separated from the jacket. It ended up hitting its mark. I have never had this happen before. Montana Gold ammo is top quality stuff. And these bullets were from long before the Sandy Hook madness, so it's not a current quality control problem. Just a cautionary tale. I'm not sure what would've happened if I shot the next round.

 

[GRIZ 3,369]

How far from the breech or muzzle was the jacket lodged?

[lunker 274]

The jacket made it to within 3 to 4 inches of the muzzle.

[NJKen 23]

You must have put one hell of a crimp on it!  LOL!

I also use MG bullets and I can say that I have never had that happen before.  It must just be some kind of fluke.  Are they brass jacketed like the 40 bullet is?  I cut one of those open and it was bonded to the lead core prety darn good. 

Ken

[Socom 19]

Chris call Montana gold tell them what happened maybe its a fluke or bad batch

[GRIZ 3,369]

I've seen millions of jacketed bullets fired and have never seen this. I don't think it has anything to do with the crimp. Speer advised to keep the velocity up on its half jacketed bullets to prevent this from happening and not go below starting loads they gave.

 

About what velocity were these loaded to?

[lunker 274]

I've seen millions of jacketed bullets fired and have never seen this. I don't think it has anything to do with the crimp. Speer advised to keep the velocity up on its half jacketed bullets to prevent this from happening and not go below starting loads they gave.

 

About what velocity were these loaded to?

That is probably it. These were mousefart loads. Probably around 700fps.

[noylj 5]

How did pressure get in the jacket to blow out the core?

How would a lead core build up a higher velocity than the lighter jacketed, that was the only thing being impacted by the pressure?

[GRIZ 3,369]

How did pressure get in the jacket to blow out the core?

How would a lead core build up a higher velocity than the lighter jacketed, that was the only thing being impacted by the pressure?

What happens at lower velocities, the bullet accelerates and when the bore friction becomes greater than the bond to the core is the jacket gets left behind and the lead core keeps going.

 

This is one of the reasons I do about 95% of my pistol loading with lead bullets. If you're going to shoot light loads there is no need for a jacketed bullet IMO.

 

Lunker, probably not enough barrel in a revolver to cause this. I'd jack up the velocity to about 900 fps in a handgun to prevent this.

[lunker 274]

Sounds like I need to shoot these out of my 4" barrel revolver. The Rossi carbine has too much barrel. Next batch gets loaded a little hotter. My initial post mentioned blue dot. That's what I used in my magnum loads. I was using Trail Boss in the load that went wrong. Thanks for the advice Griz.

[njpilot 671]

What happens at lower velocities, the bullet accelerates and when the bore friction becomes greater than the bond to the core is the core gets left behind and the lead core keeps going.

This is one of the reasons I do about 95% of my pistol loading with lead bullets. If you're going to shoot light loads there is no need for a jacketed bullet IMO.

Lunker, probably not enough barrel in a revolver to cause this. I'd jack up the velocity to about 900 fps in a handgun to prevent this.

It wasn't a handgun, it was a lever action rifle.

[raz-0 1,259]

I know the open gun crowd had some issues with mg bullets several years back, even if they didn't. Cleaning up after a match, you'd find the jackets for mg hollow points mid range when ever we had a long range classifier in the 50 yard pit. Opened up kind of like little brass versions of shotgun wads.

 

Their jackets are very springy brass that is pretty hard and it can cause issues.

[GRIZ 3,369]

It wasn't a handgun, it was a lever action rifle.

I realize that but 900 fps in a revolver should get the velocity to over 1000 fps in a carbine. That will keep the jacket on the bullet. I never used these bullets but looked at a picture. The cannelure looks good (which helps keep the lead and jacket together) but the scallops or petals around the exposed lead looks like a weak point that would encourage jacket separation.

 

The easy answer is to use lead bullets for lighter loads.

[tony357 386]

interesting. looks like you did that on purpose.

 

That would make one hell of a wadcutter..

[njpilot 671]

I realize that but 900 fps in a revolver should get the velocity to over 1000 fps in a carbine. That will keep the jacket on the bullet. I never used these bullets but looked at a picture. The cannelure looks good (which helps keep the lead and jacket together) but the scallops or petals around the exposed lead looks like a weak point that would encourage jacket separation.

 

The easy answer is to use lead bullets for lighter loads.

ok GRIZ, just thought you might have missed that it wasn't a handgun,

[raz-0 1,259]

ok GRIZ, just thought you might have missed that it wasn't a handgun,

 

Doh , i missed mentally processing that seeing the pictures.  I'll go with GRIZs answer then. Let me guess, it was stuck somewhere around where one of the several cuts are made to the barrel for sights, magazine attachement, barrel band, etc. are located.

[GRIZ 3,369]

Doh , i missed mentally processing that seeing the pictures.  I'll go with GRIZs answer then. Let me guess, it was stuck somewhere around where one of the several cuts are made to the barrel for sights, magazine attachement, barrel band, etc. are located.

I see what you're driving at but the problem is the bullet not the gun.

[raz-0 1,259]

I see what you're driving at but the problem is the bullet not the gun.

Nah, not a gun problem. Just that something like a lever gun with a number of post rifling cuts/machining is likely to bring that fact to light more readily.

 

 

[GRIZ 3,369]

Lunker, is that 700 fps from a revolver or rifle? At 700 fps that carbine barrel is most likely slowing that bullet down. I've chronoed 9mm loads found that a subsonic 147 gr bullet pretty much stays about the same velocity in a G26 or MP5 but slows down 100-150 fps in a Marlin or Hi Point carbine.

 

If your load is 700 fps in a revolver I'm guessing its 600 or less in the carbine.