357 sig ppc brass problems

Reloader90 · February 17, 2019, 03:34 PM

Hi all! My first post so if this has already been gone over I'm sorry!
I have a 357 sig in a blowback operated AR platform rifle with a 16" barrel that I am having a lot of trouble with. My first issue is that i am not able to keep the shoulder from deforming when I shoot loads that are mild to hot reloads. It's pretty much straightening the shoulder out except it works fine on the first shot then the rest are blown out. I have a wolff xp spring and a kvp 10oz buffer installed. Tried the kvp 7.5oz buffer also and the kvp but that didnt make it any better. Also tried the tubb spring. If that wasnt bad enough now today the cases that I've reloaded are separating when there fired. I tried using staring loads with a 125gr bullet and it's still separating on me! I don't know what is going on! I have been shooting reloads in this gun for a week with no problems but all the sudden today it's doing the separating.

Nanuk · February 17, 2019, 11:14 PM

I would check the chamber. Even a blow back should not be moving before the bullet is gone and pressure dropped considerably. My 40 S&W PCC will rip aluminum cases in 2.

I am running the Taccom 3g buffer system.

Reloader90 · February 18, 2019, 01:57 PM

That's crazy. What about the chamber do I need to check? The guy I bought the barrel from said I should try to polish the chamber some and so I did but am still having issues. Should I get a gunsmith to look at it??

bfoosh006 · February 24, 2019, 03:08 PM

Sounds like you've delayed bolt movement as much as possible.

Off the cuff, the only other way slow bolt movement would be from a shorter barrel... milliseconds shorter barrel pressure time. the .357 Sig might not be the best choice, just because of the shoulder.

You may not want to hear this, but you might need to consider a 40 S&W version... just because of the "straight walls" of the cartridge.

February 17, 2019, 03:34 PM	#1
Reloader90 Junior Member Join Date: February 5, 2019 Posts: 2	357 sig ppc brass problems Hi all! My first post so if this has already been gone over I'm sorry! I have a 357 sig in a blowback operated AR platform rifle with a 16" barrel that I am having a lot of trouble with. My first issue is that i am not able to keep the shoulder from deforming when I shoot loads that are mild to hot reloads. It's pretty much straightening the shoulder out except it works fine on the first shot then the rest are blown out. I have a wolff xp spring and a kvp 10oz buffer installed. Tried the kvp 7.5oz buffer also and the kvp but that didnt make it any better. Also tried the tubb spring. If that wasnt bad enough now today the cases that I've reloaded are separating when there fired. I tried using staring loads with a 125gr bullet and it's still separating on me! I don't know what is going on! I have been shooting reloads in this gun for a week with no problems but all the sudden today it's doing the separating.

February 17, 2019, 11:14 PM	#2
Nanuk Senior Member Join Date: January 2, 2005 Location: Where the deer and the antelope roam. Posts: 3,082	I would check the chamber. Even a blow back should not be moving before the bullet is gone and pressure dropped considerably. My 40 S&W PCC will rip aluminum cases in 2. I am running the Taccom 3g buffer system. __________________ Retired Law Enforcement U. S. Army Veteran Armorer My rifle and pistol are tools, I am the weapon.

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February 18, 2019, 01:57 PM	#3
Reloader90 Junior Member Join Date: February 5, 2019 Posts: 2	That's crazy. What about the chamber do I need to check? The guy I bought the barrel from said I should try to polish the chamber some and so I did but am still having issues. Should I get a gunsmith to look at it??

February 24, 2019, 03:08 PM	#4
bfoosh006 Senior Member Join Date: February 17, 2009 Posts: 1,089	Sounds like you've delayed bolt movement as much as possible. Off the cuff, the only other way slow bolt movement would be from a shorter barrel... milliseconds shorter barrel pressure time. the .357 Sig might not be the best choice, just because of the shoulder. You may not want to hear this, but you might need to consider a 40 S&W version... just because of the "straight walls" of the cartridge.