SBR AR15 is jamming - HELP ME

[44 MAGNUM SHOOTER]

Okay, today my Rock River SBR has been jamming just about every tenth round. It ejects the shells just fine but the timing on chambering the new round on occasions seems to be off and it crushes the shell between the bolt and the chamber.. I've tried the following..

Tried both my Magpul's 30 rounders
2 other aluminum 30 rounders
XM193 and Remington .223 ammo
Removed my PWS TTO Brake
I replaced the standard buffer with a Spikes Tactical Heavy Buffer
Completly cleaned the bolt and all internals of it

Still jams after an x number of shots everytime. Below are some pics.

it has an 11.5 barrel and a young manufacturing chrome m16 bolt carrier.

Any other idea's? Heavier or lighter buffer spring maybe?

 

[2ADMNLOVER]

Okay, today my Rock River SBR has been jamming just about every tenth round.



PROBLEM

PROBLEM SOLVED

 

[jdhaines]

PROBLEM SOLVED

Quote for Truth!

Sorry to the OP...no knowledge on ARs, but that was too good to pass up!

 

[Fargo]

Have you made sure the BCG is able to move freely fully to the rear? Does it lock open on the last round? Did it run fine prior to today?

Best,

Joe

 

[44 MAGNUM SHOOTER]

PROBLEM SOLVED

LOL !

 

[44 MAGNUM SHOOTER]

Have you made sure the BCG is able to move freely fully to the rear? Does it lock open on the last round? Did it run fine prior to today?

Best,

Joe

It seems to travel to the rear just fine an a couple of times the bolt did not lock back after the last round was fired.

Last fall it ran fine and I just shot it for the first time today and it's doing this

 

[451_Detonics]

Get a can of carb cleaner with one of those little red straws and really hose out the gas tube.

 

[phylodog]

Is it a factory built 11.5" barrel or cut down from a longer barrel? If it's been cut down was the gas port opened up at all?

I have a Krink flash hider you could put on it to see if that would correct the issue. If it does then I'd say you're not getting enough gas into the system to function properly. A lighter buffer might help if this is the case.

Also check for proper gas tube alignment. Remove the upper from the lower then remove the charging handle and take the bolt out of the bolt carrier. Once this is complete put the bolt carrier back into the upper (leave the charging handle and bolt out) and hold the receiver with the muzzle dipping toward the ground enough to allow the bolt carrier to slide under it's own weight into the forward position. If it stops or jumps when your carrier key gets to the gas tube then you need to adjust (a large flat tip screwdriver works well for this) the gas tube until it doesn't hit your gas key on the forward stroke.

 

[phylodog]

You might also check your gas rings. With the BCG fully assembled, extend the bolt all the way out then gently place the BCG on a table on the face of the bolt. If it remains fully extended or drops slowly you're good to go. If it bolt retracts quickly into the bolt carrier it might be time for new rings. The one piece rings work well from my experience.

***This is not an end all, be all test. I have a 10.5" rifle that runs like a sewing machine and fails this test horribly so your mileage may vary.***

 

[44 MAGNUM SHOOTER]

Here are pics of the crushed shell

 

[44 MAGNUM SHOOTER]

You might also check your gas rings. With the BCG fully assembled, extend the bolt all the way out then gently place the BCG on a table on the face of the bolt. If it remains fully extended or drops slowly you're good to go. If it bolt retracts quickly into the bolt carrier it might be time for new rings. The one piece rings work well from my experience.

***This is not an end all, be all test. I have a 10.5" rifle that runs like a sewing machine and fails this test horribly so your mileage may vary.***

tried that, thanks. It stayed in place.. driving me crazy

 

[44 MAGNUM SHOOTER]

Get a can of carb cleaner with one of those little red straws and really hose out the gas tube.

will try that, thanks.

 

[44 MAGNUM SHOOTER]

Is it a factory built 11.5" barrel or cut down from a longer barrel? If it's been cut down was the gas port opened up at all?

I have a Krink flash hider you could put on it to see if that would correct the issue. If it does then I'd say you're not getting enough gas into the system to function properly. A lighter buffer might help if this is the case.

Also check for proper gas tube alignment. Remove the upper from the lower then remove the charging handle and take the bolt out of the bolt carrier. Once this is complete put the bolt carrier back into the upper (leave the charging handle and bolt out) and hold the receiver with the muzzle dipping toward the ground enough to allow the bolt carrier to slide under it's own weight into the forward position. If it stops or jumps when your carrier key gets to the gas tube then you need to adjust (a large flat tip screwdriver works well for this) the gas tube until it doesn't hit your gas key on the forward stroke.

It came with a 10.5 originally but I replaced it with a wilson 11.5 heavy barrel and it ran fine last year. I will try an you suggest

 

[E5RANGER375]

not gettin enough gas. almost 100% sure on this one. clean the tube first. pipe cleaners work great.

oh wait. just saw the above post. when did you change the barrel?

if you want me to look at it brother, you got my info. id be happy to, any day. I'll be in your neck of the woods this weekend sometime.

 

[44 MAGNUM SHOOTER]

not gettin enough gas. almost 100% sure on this one

More than likely I assume...

 

[Fargo]

It seems to travel to the rear just fine an a couple of times the bolt did not lock back after the last round was fired.

Last fall it ran fine and I just shot it for the first time today and it's doing this

If it isn't locking open, you are short stroking for some reason. It could be not enough gas OR too much gas causing hard extraction due to timing issues.

Are the rims of the cases chewed up where the extractor grabs them and are there smear marks from the ejector on the headstamp? Going to a heavier buffer usually helps if you are overgassed, so it may be a gas port size problem. Have you checked to make sure your FSB isn't canted at all?

Best,

Joe

 

[pftraining_in]

Never push anything into the gas tube. The gas tube is closed on one end and you will push junk into the gas port. New gas tubes are cheaper than creating a single shot.

How is your gas block attached? If the gas block is held on by screws, you could be loosing gas due to improper alignment or leakage.

Is your gas key staked correctly?

If your carrier is a National Match M-16, it could be the improper weight for the rifle to function. Some National Match bolts are lighted up for match guns.

Extra power buffer springs can be a fix, however they also can be a band-aid if the rest of the system does not run properly.

Are you shooting 5.56 or .223? What chamber is the barrel cut to? Have you checked the chamber for actual caliber.

Was the barrel nut torqued to proper specs after the barrel was replaced?

 

[Don]

It is a under gas issue, have you tried other ammo?

 

[44 MAGNUM SHOOTER]

not gettin enough gas. almost 100% sure on this one. clean the tube first. pipe cleaners work great.

oh wait. just saw the above post. when did you change the barrel?

if you want me to look at it brother, you got my info. id be happy to, any day. I'll be in your neck of the woods this weekend sometime.

Thanks, may take ya up on it.

 

[44 MAGNUM SHOOTER]

Never push anything into the gas tube. The gas tube is closed on one end and you will push junk into the gas port. New gas tubes are cheaper than creating a single shot.

How is your gas block attached? If the gas block is held on by screws, you could be loosing gas due to improper alignment or leakage.

Is your gas key staked correctly?

If your carrier is a National Match M-16, it could be the improper weight for the rifle to function. Some National Match bolts are lighted up for match guns.

Extra power buffer springs can be a fix, however they also can be a band-aid if the rest of the system does not run properly.

Are you shooting 5.56 or .223? What chamber is the barrel cut to? Have you checked the chamber for actual caliber.

Was the barrel nut torqued to proper specs after the barrel was replaced?

gas block is attatched by screws - it's a yankee hill 4 rail

gas key is not staked

it is a national match carrier

it is a rock river lower and upper so it is marked 5.56

not sure what the barrel was torqued to since a smith did it. may have him recheck it.