copper jacket remained in barrel in 357 mag

[boston]

While shooting outside today, temp 22 degrees, copper jacket remained in barrel but bullet exited.

Shooting a S&W model 686, 357 mag.with 4 inch barrel. Using zero brand 158gr jacketed hollow points, behind 6.3 grains of Bullseye and Wolf small pistol primers. A medium crimp with Lee FCD. Had fired 16 shots without incident, all same specs. The round in question felt and sounded light, leading me to believe it was a squib load. Surprised to find just the copper jacket in the barrel. Jacket was removed easily with brass rod. Gun has about two thousand rounds through it and no problems. Have shot at least a thousand rounds with this same configuration of bullet, powder and primer.

Couldn't find any info on searches, so thought I'd throw it out for discussion. I think it was probably a light load, but why did the bullet not remain with the jacket?

 

[7.62 Nato]

The copper jacket has the resistance against the bores rifling. The lead core has the inertia and overcomes the bond between the core and jacket, leaving the jacket in the bore. This is why you have to be very careful when using semi-jacketed bullets. Another concern is using them in a carbine if loaded for a pistol.

 

[243winxb]

The Lee FCD sized the bullet down to much. The spring back of the brass is more than spring back of lead, leaving the core loose in the jacket. The light charge let the friction of the barrel, retain the copper jacket, but the lead being a more heavy mass, kept right on going.

 

[Walkalong]

I'm glad I didn't have to say it.

6.3 Grs of Bullseye should get the bullet out every time if undamaged. It's not max, but not light either.

Speer did quit showing loads with 158 Gr jacketed bullets in .38 Spl., but 6.3 Grs of Bullseye is around a 50% overcharge for .38 Spl pressures though.

I am assuming .357 brass since it would be an overload for .38 Spl brass.

 

[243winxb]

Old Alliant data shows 6.8gr Bullseye as maximum. But he didn't have a full powder charge is my guess. His 6.3 gr load should blow anything out the barrel.

 

[Walkalong]

His 6.3 gr load should blow anything out the barrel.

I agree.

 

[kelbro]

I agree with 243winxb. The cores are soft and easily swaged. Is there not a cannelure on that bullet for a roll crimp?

 

[boston]

Yes, there is a cannelure on this bullet for the roll crimp.

Once it's explained it makes sense. Just hadn't heard of this before. These are semi jacketed bullets, so will be sure to double check all loads in future as pointed out by 7.62 Nato. Just goes to show that you can never be to careful.

Thanks to 243Winxb for the crimp and resistence info.

 

[Walkalong]

These are semi jacketed bullets

Semi Jacketed, or Half jacketed? Either way, the warnings pictured can be applicable. .38 Spl data here, but the waring is what's appropriate. 6.3 Grs of Bullseye should have worked unless the bullet was swaged down in the case, or there wasn't 6.3 Grs in that one.

 

[243winxb]

"The Lee FCD sized the bullet down to much." Or It may be possible that the final forming step in making the bullet was missed for some reason, resulting in a loose core.

 

[Steve C]

The round in question felt and sounded light, leading me to believe it was a squib load. Surprised to find just the copper jacket in the barrel.

The load was definitely a light load, likely a failure in the powder drop due to bridging and failure in quality control proceedure to detect it.

Its been common knowledge that light loads can stick the jacket in the barrel.

The problem has nothing to do with the Lee FC die as it doesn't size the bullet unless the case diameter in the bullet shank area is greater than the SAAMI maximum allowable diameter for the case.

I would suggest you review your QC procedures and check the charged cases to make sure that they have the proper level of powder in them. In a single stage press this is usually done visually in the case block where powder levels can be compared to each other. In progressives you should have a visual check for each case after the charge is throuwn or use a "powder cop" die that locks the press if not enough powder is present.

Another issue could be that if the light charge came from bridging in the powder measure drop, the subsequent round may have been given on over charge as any remaining powder plus the next drop could have been added.

 

[Walkalong]

the Lee FC die as it doesn't size the bullet unless the case diameter in the bullet shank area is greater than the SAAMI maximum allowable diameter for the case.

If it is in spec.

I do agree that it is most likely a light charge.