Wont lock back on empty magazine with overgassed upper

[SHERWINVILLARETE]

Im not getting a lock back on an empty mag with an overgassed upper. It happens when I use my older (about 4 years old) PMAGs. Works ok with newer mags. The rifle ejects about 2 oclock with brass cased ammo, 3 oclock with steel cased.

I swapped out the upper with a well gassed upper that ejects at 3-4:30 with brass and 5 oclock with steel cased. Still using the same lower, same mag, the only thing that changed was the complete upper, and the it locked back every single time.

Im guessing the bcg velocity is too fast for the worn out magazine?


Im gonna try a full auto bcg and a heavier buffer next time and see if that makes a difference.

[matemike]

Don't change too much at once. I'd start with a heavier buffer first as you mentioned. Next, try a springco blue spring.

BTW what buffer weight are you using and how old is the spring?

Are the gas rings and gas key in good shape on the problem bcg?

Whatever you do, only make one change at a time.

[Inkslinger]

Maybe try some new magazine springs.

[Clint]

How about correcting the gas drive with the upper?

Also, what buffer is in there currently?

[SHERWINVILLARETE]

Im using just a standard carbine buffer and flat wire spring.

[markm]

The standard carbine buffer is worthless. I can't think of a set up where that thing is right.

As Clint said... Correcting the gas is step one. An H2 carbine buffer is where you want to be for almost every correctly gassed carbine set up. I don't mess with aftermarket springs.

[SHERWINVILLARETE]

The standard carbine buffer is worthless. I can't think of a set up where that thing is right.

As Clint said... Correcting the gas is step one. An H2 carbine buffer is where you want to be for almost every correctly gassed carbine set up. I don't mess with aftermarket springs.

Hmm. A carbine buffer is right for well gassed guns or undergassed guns.

I dont think its the spring cuz the spring worked well for the longest time on multiple uppers.


Im no expert, but what weight buffers do the military use on their M4s?

[markm]

Hmm. A carbine buffer is right for well gassed guns or undergassed guns.

A regular Carbine buffer would only work good on an undergassed gun. It's WAY too light, and has been very problematic on civilian/overgassed guns for years.

Im no expert, but what weight buffers do the military use on their M4s?

I think the currenty M4s come with H buffers.

[JD Williams]

Current spec is an H buffer about 3.8 oz. I used a BRT insert to cure the same problem you are describing. Well gassed guns are glorious!

https://www.instagram.com/p/CIjxmThp...=19urqshx1b8gm

Unless you are controlling the gas at the source various and sundry other parts are at play.

ETA: H buffers are what I’m getting in my 6920s, sorry for the confusion.

#prettysurethatsbroken

[markm]

Well gassed guns are glorious!

AMEN! I've had barrels in the past that were SO over gassed, they also outran the bolt catch. Absolute misery to shoot. I didn't even shoot my first SBR hardly ever because I just thought short guns were brutal.

The decades of idiotically spec'd ARs by morons in the manufacturing realm were tough times for the platform. It's how the AR piston stupidity got started.