Hey guys, took a new 13.9" mid length build out last night for a function check and ran into some short-stroking issues using ammo and mags that have never caused problems in the past. Also tried running two different lowers, one that was a standard carbine with an H2 buffer and the other is a new A5, in which I tried both an H2 and H1 buffer to the same effect. I was getting bolt over bullets malfunctions at first, but after blasting through a few boxes of ammo it is now just a won't lock back on an empty mag problem.

I have read through the flurry of posts made here on this issue, both active and archived, along with watching quite a few YouTube videos on the subject and I have a pretty good idea of all the things that it could be. So starting from the cheapest/easiest option, I was thinking about going with a lighter spring, with the choices being either the TTI Ultimate Light-Speed buffer spring or a Tubbs Lightweight flat wire spring.

Again, I am aware of all the things that could be causing the issues, and for the sake of sparing us all redundancy and re-hashing the same stuff over again, just looking for input on whether these springs have solved minor short stroking issues for under gassed rifles, or if there's even other spring options that may work.

Thanks

I’d fix the barrel to rin a standard carbine spring and H2 buffer if you’re gonna use commercially loaded ammo.

I agree, that would be the real corrective action. But if a $15 shooting can also allow it to cycle reliably in the meantime, I'm good

Sounds like something other than spring/buffer combo since what you have tried is pretty standard.

Assuming everything is clean and properly lubed, I’d check gas block alignment first. BCG could be a bit stiff - try working the action 50-100 cycles manually to break things in a bit.

Yeah considering that it wouldn't work on either lower pretty much points to something in the upper, I feel. One thing I didn't try, and I'm pissed that I didn't, was swapping BCG's. I probably could stand to run it wetter, but the way I lube and run them has never caused an issue before. Plus, I ran a different, but same branded one, in another AR the other weekend and it was flawless. I do realize that doesn't mean this one is guaranteed to be flawless also.

I do have a bore scope coming tomorrow to check for gas block alignment. Interested to see what comes of it.

So got my bore scope and it looks like the gas port alignment is okay.

I ran a wire through the gas key on the BCG to check for obstruction and there wasn't any. The wire fed right through into the carrier.

Also took the BCG apart and dropped it into the upper, muzzle down, to see of it hung up anywhere and it was totally free. Pretty much slammed into the receiver. The gas tube protrudes into the receiver fine and the gas key and gas tube mate well.

Maybe this gun just doesn't like weaker .223, but hopefully the TTI light weight buffer spring helps with that. A lot of reviews I read on it people who had same issues as mine, some even worse, said that it cured it. We'll see...

I would try a standard carbine spring with standard carbine buffer and see if it functions.  Mid-length gas with a 13.9 barrel should function, if it doesn't with the standard spring and standard buffer, I would then swap the BCG to see if it functions.  It could be that the BCG is out of spec and not gas efficient.  With that, if you still have issues and since you verified gas port alignment, I would say the gas port may be too small.

Good points. Definitely planned on trying another BCG that I know works. I do have another AR that I can drop a carbine buffer into.

I stripped the gun, cleaned and lubed the shit out of it, and will try again running the A5 system with both a T-1 and T-2 buffer, and also a carbine lower with an H-2 and carbine buffer. Outside of that, like you said, it definitely has to be the barrel gas port size.

What barrel and what port size does it have?

13.9" should be in the .077-.079" range and push an H buffer without issue.  If it doesn't I'd start looking elsewhere (clocked extension creating drag, inefficient bolt carrier group, poor gas block seal on the gas journal, etc)

Reduced power springs shouldn't be necessary in any gun with standard components...

You need to check your head spacing. I had bad head spacing on two barrels that was causing cycling problems. I had them reamed out and both worked find after that. That will cost money so the first thing you really need to check on all your builds is the gas key/lower spacing. Watch the video below and thank me later.


https://www.youtube.com/watch?v=Z7kte3ZCILs

The whole upper is a Ballistic Advantage Hanson 13.9" built on one of their enhanced uppers. I didn't say in the OP because of the flurry of active and archived posts where as soon as BA is mentioned, the responses are basically just "well there's your problem right there; BA sucks". BCG is a SOLGW unit. I did check the two quarter check and it was good.

Took it to be the range tonight with the Taran Tactical reduced power spring and functioned as it should in both the A5 RE with T-1 buffer and also in a lower with a carbine RE and H-2 buffer, just verrry twangy. Also tried it in my DD lower with Law Folder, carbine RE, and H buffer and it wouldn't lock back on an empty either. I forgot to bring my damn carbine weight buffer, though.

So the easy "fix" is the reduced power spring. I'm not sure if the spring would make a difference, but the casings did seem to come out with less force and was throwing them at about 3:30. It also is a waste of an A5 system; I might as well just get a carbine tube and put this on another build.

I have been in contact with BA and they sent me an RMA to send the upper back and said that they would open the gas port if necessary. I know that's the real fix, I just don't want deal with the hassle. But I also want a reliable gun that doesn't need non-standard specialty parts to allow it to run.

That sounds like a  solution. I think the modularity of the AR platform has fooled people into thinking that if the parts they toss together don't run then it's junk, unreliable,  and too much hassle. The fact is, a good gun is the product of a knowledgeable person with skills. Now, that person (or people) might have left those parts unassembled for the end user to fiddle with or might have assembled them him or herself. Since tolerance stacking is a thing it's surprising that as many home modified ARs run as well as they do. You probably wouldn't try half of the mods on a Rem 700 or a BAR action as you'd try on an AR.

Don't think of this as some sort of exception to the way firearms repair is supposed to be. Rather, consider all of the work that the layperson can do to the AR platform the exception and that sending it in for warranty repair is simply normal business.

What scope is that?

Also, as posted, a good spring and h2 buffer will solve most issues.

Make sure you have a good extractor/ ejector spring as well.

It's an H-2 and G33. It may look weird in the pic because it's flipped to the side

Just to follow up and close out the post, BA did send me an RMA to return it and they opened up the gas port to the next size. Just left the range and ran a couple hundred rounds through it with no issues and a great ejection pattern running an A5 system and a T-2 buffer weight.

A5 systems require you to run A5 buffers in them... you're not using a standard length buffer in that, are you?

No sir, the BCM T-2 that came with the whole Mk2 system. I had also bought a T-1 on the side. Once BA opened the gas port, it ran either one without any big difference in feel or ejection pattern, so pretty much wasted my money on that one.

That is a great video; I had 3 out of 5 ARs with too small a gap.

Did you try a standard buffer and spring?

std  2.875 oz
H    3.8
H2  4.8
H3  5.8

carbine action spring
10.7" long
0.94" OD
36     turns

It's an A5 type system, so no I didn't try running a carbine spring. But I BA did open the gas port and that solved the problem