Ar 15 probs...

[Trampstamp]

Lol it would seem so, and, you'd be correct. Light gr have ideal trajectories IMHO. But, at 1:9 you *could* throw heavier stuff down the pipe and it would be more or less usable. .223 Is common and readily available. It's just a good all around barrel. 18 inch is a good do all length imo. This build won't make anybody happy. Because it's middle of the road. I know it won't do anything spectacularly we'll. But it should do almost everything "good enough"


Which brings me back to why I kinda want a rifle length or a5 boing boing aperatus. It's more versatile. (Theoretically)




If shtf and I need to feed it 5.56, I'm sure that a barrel that chunky is gonna be a ok eating the slightly higher pressures temporarily.

 

[C-grunt]

1) get a full spring back in the gun. A shortened spring is going to cause issues. Your failure to chamber is probably because of that.

2) either get the Vltor/BCM A5 system or the correct buffer for a rifle on a carbine lower. The heavier buffer will not only slow down the action, it will also give you more oomph when chambering.

3) check your BCG for gas leaking around the key. It soulds like the cotter pin very well could have been the original issue, but check just to make sure.

 

[wesmonster]

Good advise here. If it's undergassed, and opening up the port isn't your first option, a Sprinco yellow is considerably lighter than factory. A rifle system will be smoother but IMHO you'll have an easier time sticking to a carbine system.
I run a 14.5" midlength and while that makes for a short dwell time like your 18" rifle setup, it's reliable with all types of ammo including steel case except Tula, which seems to be a much slower burning powder.
A lightweight carrier is another option. I have an 8" .300bo upper that wouldn't cycle subs, and I don't run a can, so swapped the FA carrier & std. buffer spring with a lightweight carrier & Sprinco yellow, runs everything now and can handle an H3 buffer with suoersonic loads.

 

[wesmonster]

One more thing, and apologies if it was covered, but I'd also check for a loose or misaligned gas key.

 

[Trampstamp]

Fwiw gas port is .098" so probably just fine. I don't see any sign of gas leak anywhere. I really think the initial issue is solved and I'm just waiting on a spring. I won't get to the range until later this week anyway

 

[Charlie98]

Please follow up... inquiring minds want to know!

 

[Trampstamp]

I'm back from the range. Ended up going with a BCM buffer setup. I appreciate the almost average adult size LOP it offers!! Gun cycles fine except for a couple mags have their issues. One of my Daniel defense mags had problems picking up rounds and one of my pmags only locked open on last round with heavier ammo.

 

[LiveLife]

.223 18 inch bull barrel with rifle length gas tube ... Carbine buffer tube/spring/weight ... fail to eject, wouldn't cycle at all. Empty case still in chamber

FWIW, I build/run 18" .223 Wylde barrel ARs with mid-length gas system and carbine buffer/spring and they work fine with everything.

 

[Trampstamp]

FWIW, I build/run 18" .223 Wylde barrel ARs with mid-length gas system and carbine buffer/spring and they work fine with everything.

Right, I'm pretty sure my rifle length gas system would be fine on a carbine buffer but for 2 things

1. I'd have to play with buffer weights all day

2. At the end of the day, it's too short for my lanky arms


After the dust settled I'm pretty sure there was some debris in the gas system the first day I tried the gun. I should have gone inside, tore down, cleaned, lubed, inspected, shot the next day. But light was fading and I got impatient. Maybe at some point, for science, I'll swap to my carbine lower. But this gun is really nice I like the slow rifle recoil it marches up to my shooting cadence and open sight target acquisition. 100yard mag dumps are all on target. Can't wait to see what I can do at 300 with irons

 

[d2wing]

The problem with an 18 inch barrel with a full length rifle gas system is not enough dwell time. The rifle will only function with more powerful 5.56 loads probably. Dwell time is the time it takes the bullet to travel from the gas port to the end of the barrel. That is when it is producing pressure to operate the bolt. A mid length gas system would work better. It is not a problem with the bolt or buffer system. A very light buffer and soft spring might help.

 

[Trampstamp]

I'm back from the range. Ended up going with a BCM buffer setup. I appreciate the almost average adult size LOP it offers!! Gun cycles fine except for a couple mags have their issues. One of my Daniel defense mags had problems picking up rounds and one of my pmags only locked open on last round with heavier ammo.

The problem with an 18 inch barrel with a full length rifle gas system is not enough dwell time. The rifle will only function with more powerful 5.56 loads probably. Dwell time is the time it takes the bullet to travel from the gas port to the end of the barrel. That is when it is producing pressure to operate the bolt. A mid length gas system would work better. It is not a problem with the bolt or buffer system. A very light buffer and soft spring might help.

?

 

[C-grunt]

I'm still guessing you have a gas leak. Check the gas key on the carrier to see if it moves at all or the screws are loose/broken.

 

[Trampstamp]

I guess I wasn't clear. The issue is resolved. If it functions properly on usgi mags across multiple ammo types, I'd say it's good to go

 

[d2wing]

Glad you have it resolved.

 

[Varminterror]

I'm pretty sure my rifle length gas system would be fine on a carbine buffer but for 2 things

1. I'd have to play with buffer weights all day

Your expectation here is false.

AR's are a remarkably adaptable design. I've built literally hundreds of AR's, something over 600 uppers in the last 20+ years, and I've combined all different kinds of gas system lengths and reciprocating masses and lengths. As design parameters, we have options for buffer system length, reciprocating mass, gas flow, and gas port pressure (gas system length), with these 4 control parameters aligning in a multivariable tensor (4 dimensional matrix of corresponding variable combinations) with an extremely large number of functional combinations. We can build hyperlight rifles with low reciprocating mass and extremely short, high pressure gas systems, and short buffer systems, or we can build long and heavy rifles with long, low pressure gas systems, high reciprocating mass, and long buffer systems, and virtually any combination in between. We may have to tolerate different recoil impulses due to different carrier speeds, might have to tolerate extra port blast or shorter brass life, or might have to tolerate higher rifle weight, depending upon which choices we make for other design parameters, but at its core:

It's false to pretend rifle length gas systems have any problem balancing with carbine length buffer systems.

 

[Trampstamp]

Your expectation here is false.

AR's are a remarkably adaptable design. I've built literally hundreds of AR's, something over 600 uppers in the last 20+ years, and I've combined all different kinds of gas system lengths and reciprocating masses and lengths. As design parameters, we have options for buffer system length, reciprocating mass, gas flow, and gas port pressure (gas system length), with these 4 control parameters aligning in a multivariable tensor (4 dimensional matrix of corresponding variable combinations) with an extremely large number of functional combinations. We can build hyperlight rifles with low reciprocating mass and extremely short, high pressure gas systems, and short buffer systems, or we can build long and heavy rifles with long, low pressure gas systems, high reciprocating mass, and long buffer systems, and virtually any combination in between. We may have to tolerate different recoil impulses due to different carrier speeds, might have to tolerate extra port blast or shorter brass life, or might have to tolerate higher rifle weight, depending upon which choices we make for other design parameters, but at its core:

It's false to pretend rifle length gas systems have any problem balancing with carbine length buffer systems.

None of this is relevant but I appreciate the general information.