Once You Go 300 Blackout

[SuperiorDG]

Okay so I just figured it better I start a new thread then hoop on another one. I can't believe this is only happening to me. Just got a new 300 blackout upper and shot it for the first time over the weekend. A problem came up that has to be a problem everyone who shoots the Hornaday 110 gr. V-max. I keep getting a "smoke stack" with a round in the chamber every 3 shot or so and the bolt keep locking back after only a round or two as if the mag was empty. I think the problem is the ammo and how it sits in the mag. (pictures below). What do you all think?


The first photo is the mag with the v-max ammo tapped forward, second is with mag tapped back and third is Remington 220 gr. ammo. Being that the v-max is shorter I can tap it back and forth in the mag leaving a gap in back with ammo tapped forward. This gap I think make the gun see it as empty thus locking the bolt back. I was pretty pissed so I never got around to shooting the 220 gr. stuff but I assume it would run fine. I was about ready to sell that bitch right then and there but no one was around. Anybody else have this problem?

[TheBelly]

That's.....not supposed to happen. Can you try those magazine in another gun, like a .223? How about that BCG in another gun? Does it do it with other magazines? How does the bolt catch compare to other guns?

seeing as the bottom half of the bullet, and the entirety of the operating system, is the same as a .223 I ask about localizing it to the magazine or the bolt catch being loose, out of spec, too big, etc....

[SuperiorDG]

I'll recheck all that, but everything except for the new upper was running fine with my .223 upper, same lower, same BCG, same mags.

[TheBelly]

It doesn't make sense!!

[SuperiorDG]

Was told I needed lighter buffer. We will see

[ray1970]

I can't see how it could lock the bolt back when there are still rounds in the magazine. The magazine follower is what locks the bolt when the mag is empty. With rounds still in the magazine (even shifted forward) the follower is too low to catch the bolt.

I'm thinking you might have other issues.

That isn't a 20 round pmag, is it? I had some feed issues with those. Seems that internal rib comes up higher in the 20 rounders than the 30 rounders. It was catching the edge of the case mouth and causing feeding problems for me.

[Monky]

I think you need to give me the upper and just give up.


Sent by a free-range electronic weasel, with no sense of personal space.

[SuperiorDG]

I can't see how it could lock the bolt back when there are still rounds in the magazine. The magazine follower is what locks the bolt when the mag is empty. With rounds still in the magazine (even shifted forward) the follower is too low to catch the bolt.

I'm thinking you might have other issues.

That isn't a 20 round pmag, is it? I had some feed issues with those. Seems that internal rib comes up higher in the 20 rounders than the 30 rounders. It was catching the edge of the case mouth and causing feeding problems for me.

See what you are saying. They are 30 round 3rd gen PMAGs

[SuperiorDG]

I think you need to give me the upper and just give up.


Sent by a free-range electronic weasel, with no sense of personal space.

Monky, we need to put together a fund for you so you can get that 300 Blackout you keep asking for.

[Monky]

I've got three. Two are fraternal twins.


Sent by a free-range electronic weasel, with no sense of personal space.