Overshooting brass deflector, how to correct?

[Megalomaniac]

While breaking in my new carbine, I find that as the carbine gets hot and as you increase the cadence of fire that on occasion a spent casing will just miss the shell deflector, normally this wouldn't be a problem but I shoot lefty and a hot shell to the face/neck is no fun.

The carbine is setup as follows, 16" PSA Lightweight Midlength Upper, DSA LPK, and Standard Carbine buffer.

Would switching to an H buffer or heavier improve the ejection pattern?

[Iraqgunz]

My first thought is that you are possibly overgassed. I would try an H buffer and POSSIBLY a blue Springco spring. I happen to like the Springco springs and use them in a variety of builds.


While breaking in my new carbine, I find that as the carbine gets hot and as you increase the cadence of fire that on occasion a spent casing will just miss the shell deflector, normally this wouldn't be a problem but I shoot lefty and a hot shell to the face/neck is no fun.

The carbine is setup as follows, 16" PSA Lightweight Midlength Upper, DSA LPK, and Standard Carbine buffer.

Would switching to an H buffer or heavier improve the ejection pattern?

[GTifosi]

Not to tread on IG's advice but to simply gather information:
Semi auto or full auto BCG
o-ring present on extractor or not

[Megalomaniac]

Full BCG, insert but no O-ring on the extractor.

[MtheN]

I am no expert and this is my first post here or on AR's period. I have the same upper as you. When I was breaking mine in, I was having dented brass problems. It was hitting the deflector hard enough it was denting the case just below the shoulder and bending in the neck. I had a regular carbine buffer. I put an H buffer in and no more dented brass.

PS, I have been reading this site for quite a while. You guys are great! Thanks for all of the great info!

[GrumpyM4]

So the brass is ejecting fast enough that it's exiting the ejection port before it has a chance to hit the brass deflector?

Sounds to me like under-gassed or some issue that is mimicing under-gas/slow bolt cycle.

For these reasons, I wouldn't suggest swapping out to a heavier buffer.

First of all, what kind of ammo?

Is it locking the bolt back on the last round of the magazine every single time?

Next, double check the carrier key. Make sure the screws are tight and staked.

And are you keeping the gun well lubed?

If your using good 5.56mm ammunition, it's locking back on the last round of every magazine,, the carrier key is tight and staked, and the gun is well lubed, perhaps then would be the time to add an "O" ring to slow ejection a little bit.

Lastly, how many rounds down the pipe so far?

If not many, it could simply be a case of new parts breaking in and it'll work itself out in a few hundred rounds, give or take.

[djmorris]

I think you should undoubtedly be running an H buffer if you're breaking in a 16" mid length, but that's just me.

[Megalomaniac]

Fired around 60rds of 55gr Wolf and around 200rds of 62gr also steel cased (Not sure what brand, shooting buddy supplied and I wasn't there when he dumped them into his ammo bag.) Didn't get to fire anymore as we only had an hour of range time.

Carbine was shot swimming with lube, it locked back 100% of the time with several different mags.

Carrier is tight and well staked as well.

[AKDoug]

My DD 16" middy runs an H buffer and it runs good. Definitely worth a try, but there are a ton of variables to consider.

[MarkG]

... on occasion a spent casing will just miss the shell deflector...

Forget the ejection pattern nonsense. Reliable extraction is the ONLY consideration. The fact that it is an intermittent problem points to cheap ammunition. A heavier buffer or action spring will only exacerbate the problem. You have to test fire it with high quality military pressure ammo before moving forward.

[Megalomaniac]

I don't care about ejection pattern so long as the rounds aren't flying into my face, as being a lefty shooter they tend to fly there when they miss the deflector.

I'll have to grab some m855 or xm193 to test it with, but this gun will spend most of its time eating steel cased since it is mainly a plinker.

As far as it being intermittent it was happening rather reliably as far as temperature, if it started spitting cases I cleared the carbine and got some trigger time with a Saiga 12, then went back after a few minutes and the issue would not repeat until part of the way through a mag.

[Sticks]

This almost sounds like you have a gas leak at the gas block where the heat of the barrel is either sealing it or making it worse as the temp rises and the metal expands (not sure what type of BCG speed condition would cause the change in ejection). Possibly lube on the BCG, or lack thereof, being affected by the same (temps).