AR won't cycle 55 grain ammo

C.Magnet

C.Magnet

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I have recently assembled an AR using mostly Aero Precision parts, with a 14.5" Ballistic Advantage barrel with a mid-length gas system.
I realize that a mid-length gas system paired with a 14.5" barrel will result in a relatively low gas impulse, but fully expected it to be able to reliably cycle 55 grain factory 223. It seems to run well with 62 grain 223 and 5.56 (It is chambered in 223 Wylde)
I thought maybe I bought a buffer that was too heavy without realizing it, but it is not marked, which would indicate it is a carbine buffer.
Any suggestions? is it a no no to open the gas hole in the barrel slightly?
 
Try a reduced power spring (Wolff makes them, prob others as well), at $15 usd it looks like the cheapest and easiest thing to try. Assuming you have a std buffer...
 
C.Magnet said:
I have recently assembled an AR using mostly Aero Precision parts, with a 14.5" Ballistic Advantage barrel with a mid-length gas system.
I realize that a mid-length gas system paired with a 14.5" barrel will result in a relatively low gas impulse, but fully expected it to be able to reliably cycle 55 grain factory 223. It seems to run well with 62 grain 223 and 5.56 (It is chambered in 223 Wylde)
I thought maybe I bought a buffer that was too heavy without realizing it, but it is not marked, which would indicate it is a carbine buffer.
Any suggestions? is it a no no to open the gas hole in the barrel slightly?
Click to expand...

I am assuming your bolt is extracting and ejecting spent cases ok but it is failing to chamber the next round when using 55g loads?
 
Have the hole examined by a qualified gunsmith. If it needs opening just open her up. Better that than change out all the normal parts that work. If you change springs and buffer weights when you throw on another upper it won't function right. Either that or throw a noveske pig on it but that defeats the purpose of having the 14.5" barrel. Don't change what works to remedy something that doesn't.
 
Ramzzz said:
I am assuming your bolt is extracting and ejecting spent cases ok but it is failing to chamber the next round when using 55g loads?
Click to expand...

Yes, It is extracting and ejecting ( straight back, deflecting off the brass deflector) just not chambering the next round.
 
NaughtyPilot said:
I assume you've done the obvious and checked the alighnment of your gas block?
Click to expand...

How, besides shooting the gun, can that be done? the gas block is held in place by the pin, and corresponding channel cut into the barrel, so there is not any room for adjustment
 
rubberdonuts said:
Have the hole examined by a qualified gunsmith. If it needs opening just open her up. Better that than change out all the normal parts that work. If you change springs and buffer weights when you throw on another upper it won't function right. Either that or throw a noveske pig on it but that defeats the purpose of having the 14.5" barrel. Don't change what works to remedy something that doesn't.
Click to expand...

That sounds like the most likely course of action. I have emailed the manufacturer, hopefully they can provide me with the required hole size. The rifle is obviously under gassed at this point, so increasing the hole slightly shouldn't be an issue. Determining what "slightly" is, will be the key
 
You say factory ammo but what brand? Some stuff is underpowered, especially compared to 5.56mm which runs at higher pressures than .223.

If a manufacturer makes a barrel with NATO ammo in mind than it may not cycle .223 reliably. BCM and LMT come to mind.
 
minniehill2 said:
His is chambered in .223 wylde so it is slightly under gassed.
But yes, My 16" KAC loves HOT loads also.
Click to expand...

The chamber has nothing to do with the gas port although .223 Wylde will safely chamber .223 and 5.56mm. As a side note Wylde actually designed the chamber in an attempt to get as much accuracy from C77 ball ammo when he'd come up to Canada for DCRA shooting competitions when you had to use CF supplied ammo.
 
I had a Bushmaster Pistol that wouldn't cycle properly. Sent it out twice for repair, but no relief. I tried using the buffer & spring from my AR-15 rifle and it cycled flawlessly.
 
C.Magnet said:
How, besides shooting the gun, can that be done? the gas block is held in place by the pin, and corresponding channel cut into the barrel, so there is not any room for adjustment
Click to expand...

Is it a fix front sight block? Or are you saying its a pinned low pro block?

Check your gass key for tightness. The very last resort should be enlarging the gasport.
 
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