My ar pistlo is short stroking!! PROBLEM SOLVED..

[pdugan6]

I finally found out what was going on..... one of the gas key screws had snapped and so the gas was not getting fully directed to the bolt. I switched it up and it is it was as good as gold again.

[hung380]

Loose gas key on bolt carrier?
Check the 2 screws on the bolt carrier make sure they aren't loose and properly staked.

Sent from my MB860 using Tapatalk

[wash]

What kind of buffer are you using?

Too heavy buffer + light loads might do that.

Make sure your gas block hasn't moved and make sure your action is clean and lubed too.

[pdugan6]

I am using an st-t2 buffer. the gas key is solid as well.

[Deadon]

Take a tape measure and measure the inside of the buffer tube. Then measure the inside of a tube you know works on another gun.

[pdugan6]

Take a tape measure and measure the inside of the buffer tube. Then measure the inside of a tube you know works on another gun.

Same size. I am going to just try a hotter load or heavier grain bullet. we shall see.

[JamesY]

Try a noveske pig.

[wash]

Step one, try a standard CAR buffer.

If that doesn't fix it, try some ammo like Federal Lake City XM193. I've heard Fiochi is loaded pretty light so American is the way I would go to check function.

If those two changes don't fix it, start looking at your gas system.

[torquefliteterror]

what is the barrel length? We built my friend a short 7 1/2 inch and it had the most rediculously small factory gas port hole. I did my 10- 1/2 with a 3/32 and it cycles cheap silver bear all day. I don't remember the size we used on his but it was .070 range when we measured it with the digital calipers. He has since fired close to 500 rounds with zero failures. I suggest to everyone who builds a pistol to pull the gas block and check to see what size hole they have. if it looks teeny i say open it up a size or two and test it. most manufacturers port them for the expensive ammo. Also , try using the red hi temp bearing grease from walmart or an auto parts store. liberally coat the bolt head and rails on the bolt carrier and see if you just haven't run the thing dry. also don't forget to put a little oil in the side of the bolt to lube the gas rings. most of the guns I have seen at shops come dry.

[wash]

If a lighter buffer and warmer ammo cure the problem, you will know that you are operating near the edge.

You can't undo drilling out your gas port so that would be my last resort unless you find that it is way too small.

[torquefliteterror]

True, I say he should try lubing the hell out of the thing first. I just opened both my 10" guns to the Colt spec .093 I figured if it was good enough for colts sub guns it would be good enough for my model1 upper. The gas port on mine was tiny as well. it was the size of a standard carbine port. I wont port anything past 3/32 anything more would probably over gas it.

If a lighter buffer and warmer ammo cure the problem, you will know that you are operating near the edge.

You can't undo drilling out your gas port so that would be my last resort unless you find that it is way too small.

[torquefliteterror]

Here is some video of me firing one of my guns at Tumey Hills BLM. All I run through them is cheap silver bear. it use to short stroke often before the mod, now it never fails.

http://www.youtube.com/watch?v=Nj3FYzhS3tk

[pdugan6]

Thanks for the info. I am going to try some different ammo and lube her up some more.
...

[FeuerFrei]

If you want an AR pistol to be reliable with all ammo after you open up the gas port, run an adjustable gas block on it. (.077 was a sweet spot for my 7.5" DI)
It won't beat inself to death with 556 full power ammo.
Nice pistol.

[1meanchevy]

Has the same problem on my 20" bull barrel upper. After 1 trip to the local gunsmith, 1 call to another gunsmith who told me "thats just the way AR's are), three trips to local tactical shops, tons of money spent on gas tubes buffer springs and new BCG's, sampler packs of every .223 ammo & 5.56 ammo I could find (some worked some didn't) and two trips back to that factory, the damn thing still wont cycle correctly. Seems the internet is awash in advice too, only thing I can come up with is my powder Reloader 10x, is just way to fast for the gas system. Last time i sent it back to the factory they said the barrel gas hole was too small and they drilled it out.... whatever.