FTF Diagnose

[markderp]

Hi All,

Had a FTF over the weekend. Rifle has somewhere between 1-2K through it without issue. The failure occurred with a relatively new surefeed mag and 77 Black Hills TMK. The rifle ejected the spent case and the fresh round jammed nose up when clambering. The ballistic tip deformed from the force and the bullet setback quite a bit into the case. Is this likely a mag issue or potentially the neck tension on the round? I used the same mag with mk318 and federal 62 gr and had no further issues. Ran out of TMK that day but will try to duplicate the FTF with that mag and ammo in a few days.

[17K]

Surefeed. I’d try different mags. I have not seen too good performance out of those mags since they became Surefeed. Probably not gonna be a popular opinion though.

[markderp]

Thanks, I'm thinking mag as well since it's the newest variable. Previous mags and ammo ran flawless in said rifle. It's one of the e2 mags. I normally use gen 2/3 pmags but I picked up 5 of the surefeeds recently. I'm going to keep messing around with them to see if any other failures occur.

[17K]

Oh yeah, I would definitely point to the mag.

If it does it with a Gen M3, I’d get worried.

[ViniVidivici]

Concur I would guess the mag.

[MistWolf]

Has the Surefeed mag been a problem in the past? Is it a problem in any other AR?

[markderp]

Testing that on Saturday. I'll run them through two other rifles as well.

[georgeib]

I've had a particular older Magpul mag not hold the bolt open on a specific lower, but exhibit no issues on every other lower I have. Sometimes it's just tolerance stacking.