your thoughts on an ar short stroking

[foxhunter]

i have an ar with a Faxon 16" gunner match barrel, it has a rifle length gas system. i have a 6mm arc as well and it functions just fine , i took the lower off the 6mm and put it on the 22. it has a carbine length tube with collapsable stock. the rifle is a single shot, eject the spent shell but does not pick up the next shell. i pulled the buffer weight and spring, it has a red springco extra heavy duty spring and a h1 weight. i have another lower with an a2 stock and the 22 arc runs just fine on it, it has a rifle buffer weight. (6")

any suggestions? thinking of replacing the red spring with a aero mill spec to see if it will run.

 

[Laelkhunter]

Maybe a different weight buffer? Place one round in the mag and chamber. Fire the rifle and see if it locks back on an empty mag.

 

[foxhunter]

done that and it does not lock open. bc is well lubed as well. Switched magazines with same result.

 

[Laelkhunter]

Sounds undergassed. Can you try a different weight buffer? When shooting it, where do the empties land in relation to the rifle? Are they straight out 9 o'clock, slightly forward like at 10 o'clock, or behind you at 4 or 5 o'clock? Are you shooting factory or reloads?

 

[cohunt]

Sounds undergassed. Can you try a different weight buffer? When shooting it, where do the empties land in relation to the rifle? Are they straight out 9 o'clock, slightly forward like at 10 o'clock, or behind you at 4 or 5 o'clock? Are you shooting factory or reloads?

9 or 10 o clock? Are you referring to a left handed ar?

 

[Laelkhunter]

9 or 10 o clock? Are you referring to a left handed ar?

Yes, wasn't sure which rifle OP was shooting, but hopefully he saw through my poorly worded response. Thanks for your question. I guess I confused everyone.
Where the ejected brass ends up could possibly help with a diagnosis.

 

[cajun]

Under gassed. Check the gas tube alignment on the barrel and on the bolt. What kind of gas block? If the gas block is not aligned with the gas port it can cause issues. Have you used this upper before and not had issues? Last case scenario would be to drill the gas port. I have never had to do that on a standard ar only on a 6.8 I had.

 

[Critter Picker]

Sounds undergassed to me as well. Left hand brass should be 7 to 8 o clock.

 

[foxhunter]

the brass ends up at 4 o'clock with 12 o'clock being down range. buffer eight is not marked so i'm taking it with me to the post office today to weigh it. the other lower has the 6" rifle buffer that should weigh 5.5-5.8 ounces and that lower feeds and ejects just fine.
put the lower on my 6mm arc and it runs just fine and tosses the brass to the same place. if the buffer weight is the problem and it has a h1 in it i'm not sure how you get to a lighter weight. might have to go to one with variable weights.

 

[Roughrice]

Undergassed.
Take are out heavy buffer and put standard carbine buffer and standard spring.
Also check gas port alignment as Cajun said.
Also if it has adjustable gas block… open it up a couple of clicks at a time until it locks back on empty mag.
Do one of these at a time and try lockback test until you find the problem.
22 bullets usually have less mass and often won't run well when the gas or recoil system is set up to run heavier bullets.

I've tuned many of these things for people who put uppers together with random parts and didn't understand the operation.
No worries…Common problem…

 

[Laelkhunter]

the brass ends up at 4 o'clock with 12 o'clock being down range. buffer eight is not marked so i'm taking it with me to the post office today to weigh it. the other lower has the 6" rifle buffer that should weigh 5.5-5.8 ounces and that lower feeds and ejects just fine.
put the lower on my 6mm arc and it runs just fine and tosses the brass to the same place. if the buffer weight is the problem and it has a h1 in it i'm not sure how you get to a lighter weight. might have to go to one with variable weights.

If you look at the buffer, there is a pin holding it together. If you drive the pin out, you can take it apart and remove one of the weights inside it to lighten it. There might be as many as 3 or 4 metal (maybe tungsten) weights inside the buffer. Remove 1 weight and try it. If there is only one weight, then you probably need a different buffer.

 

[cohunt]

So its a 16" 223 with a rifle length gas tube? I didn't know faxon sold that combo, thought they only had carbine and mid-length gas on the 16" gunner match barrels...actually didn't know anyone sold a 16" 223 with a rifle length gas system/tube--- didn't think there would be enough dwell time for proper operation with that combo.

Your first post kinda lost me

 

[foxhunter]

sorry you're lost. it's a 22 arc not a 223 and here is the specs from their website:

• Barrel Material: 416-R Stainless Steel
• Barrel Type: 5R Button Rifled
• Barrel Caliber: 22 ARC
• Barrel Twist: 1:7
• Barrel Length: 16"
• Barrel Profile: Gunner
• Barrel Gas System: Rifle
• Inside Finish: Salt Bath Nitride
• Outside Finish: Salt Bath Nitride
• Muzzle Thread: 1/2x28 TPI
• Gas Block Diameter: .625"
• Gas Block Journal Length: 1.9"
• Barrel Extension: M4, Nickel Teflon Coated
• Weight: 1.57 lbs
• Magnetic Particle Inspected
• Recessed Target Crown

7 th one down, i like you found it odd.

 

[FireFlyFishing]

Call Faxon and see what they recommend for that upper. They surly can point you to the correct buffer and corresponding spring for proper cycling. Then you don't have to experiment. You can get the right parts the first time.