Need a AR expert advice

[DocSkunk]

Let me start this off i am no expert. If that isn't obvious of this post. I have 3 AR-15s I have built. First one still runs perfect. My other 2 one rifle chambered in .50 beo and a pistol chambered in 5.56. They are both as it appears to me be the same issue, i believe the are short stoking. They chamber manually, fire, eject, and fail to strip the next round off into the chamber. The uppers do not have adjustable gasblocks. Ill rattle off the parts list as much as i can remember in each. I am stumped. Any help would be appreciate it.


Rifle 1 .50 beo

Apache arms upper and bolt carrier
Anderson lower
HERA USA CQR Stock
TacFire AR-15 USA Made Lower Parts Kit
TacFire AR-15 4.9 Oz. Heavy Buffer
TacFire AR-15 6 Position Mil-Spec Carbine Buffer Tube


Pistol

Apache arms upper and bolt carrier
Omni polymer lower
TacFire Mil-Spec Pistol Buffer Tube w/ Foam Insert
TacFire 3 oz. Buffer
TacFire Carbine length buffer spring

 

[T.Lex]

New issue, or present from the first shot? What length gas system length?

I'm certainly not an expert, but know some of the questions.

 

[NyleRN]

Lots of potential contributing factors here. Quality of gas block and /or gas tube. I've diagnosed short stroke problems before for guys and end up being cheap gas system parts they bought from gun shows that had no packaging. So probably Chinese junk. Either gas block alignment or leaky junk parts. Are you sure the spring and weight of buffer are correct for that particular caliber?

 

[indysims]

Lots of potential contributing factors here. Quality of gas block and /or gas tube. I've diagnosed short stroke problems before for guys and end up being cheap gas system parts they bought from gun shows that had no packaging. So probably Chinese junk. Either gas block alignment or leaky junk parts. Are you sure the spring and weight of buffer are correct for that particular caliber?

Yep, start here, not enough gas, check for signs that the gas is leaking, carbon on the barrel around the gas block. Confirm the gas block is aligned. Next move to the tube, check it's alignment both with the gas block and the gas key engagement on the bolt carrier.

If all that checked out, the gas port on the barrel my be undersized, but usually they are oversized to help run cheap ammo, so I would be surprised if that were the case.

You can also disassemble and and clean the bolt and carrier, there is a chance that the bolt is not functioning properly because the gas is being impeded internally.

 

[indysims]

This guy https://www.schooloftheamericanrifle.com/ offers a TOOOOOOOON of awesome info on troubleshooting the AR platform. Check his instagram and youtube accounts.

 

[DocSkunk]

I didnt install the gas system. I bought the uppers both complete from the Fort Wayne gun and knife show from Apache Arms table a year apart from one another. They are based out of KY and have offered to look at them but i dont feel comfortable sending two full firearms to them. I also believe its the uppers. Ill play around with different buffers see if that helps.

 

[Rookie]

Check the springs. Rifle length vs carbine length

 

[Rookie]

The springs for the rifle and the carbine are the same diameter, and made of the same steel alloy. The rifle springs have 41 to 43 coils, and the carbine springs have 37 to 39 coils. The brand-new length of the springs is approximately 12.75″ for the rifle and 10.5″ for the carbine springs.

 

[Ggreen]

50 beo should use a standard carbine buffer spring and weight.

Most non Alexander arms beos have the wrong bolt. Spend the 100 dollars and get a spec bolt from Alexander. This fixes most issues.
Beo is also meant for carbine gas systems. Some knock offs were trying to use mid and rifle, results of these have never been consistent.

Swap your buffer with a standard carbine first tho

 

[ROLEXrifleman]

Check the gas key for leaks. You could have a sheared has key screw. I recently repaired a 2 month old Diamondback AR with this issue after 25 rounds

 

[Ljungman]

Short stroking always comes down to 1 of 2 things. 1. Gas leak 2. Excessive resistance/binding. 1 is easy. make sure gas blocks are not blowing gas out from under or from the gas tube hole in the block. ive seen gas blocks drilled out of spec and they leaked gas around the gas tube itself. as above - check for carbon build up in odd places. 2 - ill go out on a limb here and state that the spring probably isnt the issue. 50 beo is a stout round in its own right, so im fairly confident that would be the last place to look as the spring pressures would actually be stiffer in the carbine spring - less coils shorter gas tubes = more pressure into system. and beo was made for carbine set ups. the bolt - as above alexander does NOT share his specs with many people. most aftermarket brands make their products with out his support. the bolt may be out of spec causing excessive drag. same for out of spec carrier. check rear of carrier for wear/peening as the out of spec carriers can actually hit the extension buffer tubes or bind up in their rails. im leaning more to number 1 though. 90% of the time in my own ar's - short stroke is a gas issue.
just my 2 cents.