300 Blackout SBR problem

[jsjac]

I built a 300 Blackout SBR a couple years ago. Always had feeding problems.
Went out today with it and messed around with it. Had feeding problems again. Double feeds. Not cycling back far enough to stip off a round from the magazine.
I removed the bolt carrier and got a quart of motor oil from the truck and lubed up the bolt carrier and reassembled.
After I luded it up very well it didn't have any more trouble.

How much oil should be used on the bolt carrier.

Is there a good video how to clean and lube a AR.

 

[shoobe01]

Need more data. What gun, what buffer, what ammo, and anything else you know of is custom like an adjustable gas block, weird recoil spring, etc?

 

[10ring1]

Assume a pistol length gas system?

 

[ControlGroup]

Carbine barrel ports are trouble so hopefully you have a pistol barrel.

 

[jsjac]

The upper is a 10 inch barrel.
Not sure how to tell if it is a pistol or carbine length gas system.
Standard carbine buffer and spring.
Tried factory subsonic and my hand loads. The factory ammo worked better.
The gun worked much better after it was oiled rather heavily.

Also do not know how to tell if it has an adjustable gas block.

 

[hlee]

A pistol length gas tube is approximately 4.5 inches long. A carbine gas tube is approximately 7.5 inches long.

Look at your gas block. Does it have any exposed adjustment screws? If not, it is not adjustable. If you don't know, assume it is not adjustable.

Does it function with supers?

You will get answers to your "how much lube?" question that vary from dry to spraying oil across your face with every shot. I lean towards a light sheen.

My 300 BO pistol was having problems until I replaced the extractor with a BCM enhanced extractor. Solved all issues. Runs subs and supers equally well. Don't have a can in hand yet, but hope that trend will continue when it arrives. Pistol gas tube, heavy buffer, non adjustable gas block.

 

[nso123]

As mentioned above, does it function with supersonic ammo? My factory AAC sbr functions well with subs that are just barely sub. As for lubing, that is going to be a Ford vs Chevy discussion. I, too, like just enough lube for things to look shiny.

 

[jljr23]

Need more info.

 

[Mike_in_FL]

The gun worked much better after it was oiled rather heavily.

Regardless of when it was built, a new AR build of whatever caliber needs to be run wet with oil for a bit to break it in. If it doesn't have some form of adjustment screw on the gas block, it probably isn't adjustable. If you built it, how do you not know what you used/bought?

 

[bluegrasspicker]

It sounds like you figured it out (by adding oil). You said you didn't use if for a couple years. Depending on how it was stored, I would bet good cash money on it not cycling without a couple drops of oil.

If I were in your shoes I'd wipe it down to minimal lube just to see if it'll still run in the "somewhat neglected" condition. If so I wouldn't worry about it anymore. Then I'd add a little more lube (so it's in the "not neglected" condition) and go have fun with it.

Many times I've seen a couple drops of oil fix a sluggish (not returning home, not picking up a round, etc) ar15 or ar10/LR.

In case you have to go back to troubleshooting, know that my sbr 300blk has a carbine gas system, no adjustable gas block, and it runs perfectly. I wouldn't necessarily assume that those are the problems on yours.

 

[Thood]

It sounds like you figured it out (by adding oil). You said you didn't use if for a couple years. Depending on how it was stored, I would bet good cash money on it not cycling without a couple drops of oil.

If I were in your shoes I'd wipe it down to minimal lube just to see if it'll still run in the "somewhat neglected" condition. If so I wouldn't worry about it anymore. Then I'd add a little more lube (so it's in the "not neglected" condition) and go have fun with it.

Many times I've seen a couple drops of oil fix a sluggish (not returning home, not picking up a round, etc) ar15 or ar10/LR.

In case you have to go back to troubleshooting, know that my sbr 300blk has a carbine gas system, no adjustable gas block, and it runs perfectly. I wouldn't necessarily assume that those are the problems on yours.

Need to find load data for 300 blk 296 powder or lilgun with 168 grain bullet and subsonic