My first AR short cycle issues

[rbmuse]

Thanks gsh341 and MistWolf
I have not changed the gas block. I was going to and bought a new one and it would not fit on the barrel just a bit off of .75 inch. I have tried using a different BCG ( both are almost brand new) that did not help. I will take it apart again and check the hole in the barrel. Anyone know what it should be. This is a carbine 14.5 inch.


Sent from my iPad using Tapatalk

[rbmuse]

Maybe is should install an adjustable gas block?


Sent from my iPad using Tapatalk

[MistWolf]

An adjustable gas block won't help if the gas port is partially blocked or too small

[gsh341]

MistWolf is right. Using an adjustable gas block won't solve your problem if the problem is with the barrel.

Looking at this as simply another engineering problem you get only a few reasons for short-stroking on an AR.

1. Something is preventing the bolt from cycling smoothly in the upper receiver or buffer tube,

2. The bolt carrier group is not getting enough gas to make it cycle reliably,

3. The bolt is not trapping the gas properly and is not maintaining enough pressure inside to make it cycle.

Since your AR is cycling properly about 80% of the time, I would be looking at a gas issue. I would highly doubt that the gas port on the barrel is the problem, so that would leave the gas block or the gas tube. However, I did a search and found this on an old thread.

https://www.m4carbine.net/showthread...87#post1410287

I took these 4, brand new, stripped, unfired, mid-length gas barrels to work tonight and checked each ones gas port size with the inspection departments pin gauge set. These are exact measurements down to .001" of an inch.

BCM 14.5" CHF lightweight profile, .625" gas block: .077" gas port (I just got this barrel from Bravo Co. yesterday)
Centurion Arms 16" CHF, .750" gas block : .079" gas port
Noveske 16" CHF, .750" gas block : .080" gas port
Rainier Arms 16" Ultra Match, .750" gas block : .082 gas port

If the gas block is not lining up properly with the gas port on the barrel. you could be restricting gas flow. If the gas tube has an obstruction, it would also reduce gas flow. Finally, if the gas tube is not fitting the gas block properly, it could cause a problem as well.

It's hard to screw up a gas tube, so I would suggest swapping the gas block to eliminate any machining issues with the block. I would bet that's where the problem is. If that doesn't solve the problem, try a gas tube next. Cheap replacements for both should cost you about $30-$50.

[Tape]

What buffer are you running?


Sent from my iPhone using Tapatalk

I am wondering myself, I believe you are running the wrong parts or the buffer is not fully cycling.

[Iraqgunz]

The only way we are going to make any headway is if the OP actually tells us about the components used. Until then it's anyone's guess.

[GH41]

One more reason not to F with a 14.5" barrel.

[rbmuse]

I purchased the parts as a set from Brownells, not a lot of info on the brand etc. I am planning to take it apart today and start down the list of suggestions you guys have sent me. I will send a photo of the barrel gas hole along with the hole diameters


Sent from my iPad using Tapatalk

[rbmuse]

I am updating this on my iPad. I tried form the website on my MAC and it does not accept my log in? Anyone have this issue?


Sent from my iPad using Tapatalk

[rbmuse]

Ok it is apart now everything looks fine see photos the barrel gas hole os within the circle of the larger gas block hole. I have no way to measure the barrel hole, however I can not insert a 1/16. .0625 drill into the hole.
Looks to be just a very small bit smaller than that.


Sent from my iPad using Tapatalk