New rifle not cycling correctly

[RicosRevenge]

My first guess would say that it is a gas / buffer issue. It sounds like the bolt is short-stroking and not going all the way to the rear thus it doesn't pick up the next round at the back of the mag; but instead catches the next case after the base creating the FTF BOB that was mentioned above.

[lawndartmike]

If a rifle is at the edge of being under gassed, there are a few things that I have experienced that will cause a short stroke.

No lube in the buffer tube.

A sharp edge on the hammer dragging on the bolt.

The rings on the bolt not aligned properly.

A few more rounds to finish the break-in.

As already discussed - the gas block not aligned properly or leaking.

[Clint_taylor95]

I switched my carbine lower with an MP lower that is a rifle stock and rifle buffer. I shot his lower with my upper and it cycled perfectly. I did not get a chance to put my lower on his mP223 upper.

Conclusion: since my buddies lower worked on my upper and it cycled correctly, it tells me that it is not a magazine or a gas issue with my upper(unless it being a rifle buffer makes a difference)

My carbine lower with my upper: after shooting a round without anything in the magazine, the bolt does lock back

Does this sound like a buffer problem with my lower? Can't be a gas or mag issue since it works on his lower right, or am I missing something.

Thanks for helping me work this out folks.

[Clint_taylor95]

Update:

So I just received a 24round e-lander mag from AA, I bought some 10rounders too but they were out of stock. Shot about 10 rounds through it and my gun cycled them perfectly it looked like.

So a couple questions I have, What are the reasons why the ASC mags do not cyle correctly in my lower but will in my buddies rifle buffer lower? Is there anything I can do to make the ASC Mags work better?

[A5BLASTER]

Thats a good question on the mags Clint.

I use some 10 round Cproducts defense mags and some 5 round ASC mags I got from PF and I have yet to have a feed issue with either one of these mags that was a mag issue, my issues were gas related.

These mags are on their second upper but same lower and the lower is set up with rifle length buffer tube and SCS from JP.

So maybe its your carbine buffer is to light and causing the issue your having with it.

I hope this info helps sir and that you get it figured out soon.

[Clint_taylor95]

So I'm finally getting around again to try and figure this out. I'm going to change my buffer to see if that fixes the problem. My question are:

Can I put my buddies buffer which weighs 5.1 oz and is 6" long in my lower which is collapsible with a 10.5 inch spring?

Can I put any weight and length buffer in my lower with out changing the spring and tube and stock till I find which weight works best? I'm gonna go head and say this is a noob question.

FYI: the buffer I currently use is a standard 3oz.

[Rickc]

So I'm finally getting around again to try and figure this out. I'm going to change my buffer to see if that fixes the problem. My question are:

Can I put my buddies buffer which weighs 5.1 oz and is 6" long in my lower which is collapsible with a 10.5 inch spring?

Can I put any weight and length buffer in my lower with out changing the spring and tube and stock till I find which weight works best? I'm gonna go head and say this is a noob question.

FYI: the buffer I currently use is a standard 3oz.

No you can't put.a rifle length buffer in a carbine buffer tube.

Yes you can put.a heavier buffer in your carbine without changing the spring. Most will recommend an h2 buffer with a grendel. This will slow down the cycling rate. Could be it is cycling too fast to pick up the next round

Another possible problem is.the way the mag is fitting.in the.mag well. It.could be.sitting a little low. Why not take the.lower it.works.with and with the bolt.locked.back insert a mag.and see.how the.round is sitting in relation to the feed.ramps and the back of.the mag where the bolt is going.to pick up the next round. Compare that to your non-functioning lower.