7.62x39 Sig Sauer Spear LT 11.5'' cycling issues.

[garose21]

Hey all,

Might anyone have experience with the Sig Sauer Spear LT 11.5'' chambered in 7.62x39? I recently moved away from my 16'' upper, which had no issue, to an 11.5'' that fails to cycle properly after 3 rounds unsuppressed, and 1 round suppressed. Sounds like an issue with back pressure, but I thought I'd reach out on the forum for insight.

Any thoughts?

 

[cmshoot]

There are 8 stages in the cycle of operation. Exactly where is yours failing, and how?

 

[Bypass]

There are 8 stages in the cycle of operation. Exactly where is yours failing, and how?

Subscribed.

 

[above_all]

Stupid question on my part. If it was just a barrel swap, did you remove the 5.56 bolt and install the 7.62 bolt?

 

[garose21]

There are 8 stages in the cycle of operation. Exactly where is yours failing, and how?

I'd say extraction. I'm able to fire a round once, sometimes twice, but ultimately the 2nd or 3rd round fails to extract properly, and get caught in the chamber sideways.

 

[garose21]

Stupid question on my part. If it was just a barrel swap, did you remove the 5.56 bolt and install the 7.62 bolt?

I just swapped the barrel length. Both the 11'' barrel and the 16'' barrel are 7.62x39.

 

[garose21]

Thank you all,

After a little more research and an impromptu range day, I was able to narrow it down to the ammunition. Turns out this barrel length and caliber combination is very picky and Hornady Black 123 Grain seems to perform well in this combo.

 

[cmshoot]

I'd say extraction. I'm able to fire a round once, sometimes twice, but ultimately the 2nd or 3rd round fails to extract properly, and get caught in the chamber sideways.

The fired casing is not being fully extracted from the chamber?

When you fire the last round in the magazine while using the 11.5” barrel, does the bolt lock to the rear?

Did you swap barrels yourself, using the previous receiver, or did you swap the entire upper receiver assembly?

Is the BCG the same?

 

[Timber Cruiser]

I'd say extraction. I'm able to fire a round once, sometimes twice, but ultimately the 2nd or 3rd round fails to extract properly, and get caught in the chamber sideways.

The old stovepipe. I’d say ammo.

 

[Timber Cruiser]

Thank you all,

After a little more research and an impromptu range day, I was able to narrow it down to the ammunition. Turns out this barrel length and caliber combination is very picky and Hornady Black 123 Grain seems to perform well in this combo.

Sorry. Guess I should’ve finished reading before I threw my idea out there. Glad you got it figured out.