Bushmaster Varminter Problem

[Will Lee]

After 2 years of flaws shooting I went to the range last week and every ejected round hung up. The eject case was sticking out of the receiver at a 90% angle. Pulled the bolt back, clear the ejected round released the bolt, round from the magazine feed nicely into the chamber; fired the round, same hang up.

Completed disassembled the rifle and thoroughly cleaned everything. Did not solve the problem.

Anyone had this problem & if so what was the fix?

Thanks for any input

 

[Bartholomew Roberts]

Completed disassembled the rifle and thoroughly cleaned everything. Did not solve the problem.

Did you disassemble the both assembly to remove/clean the extractor and ejector pin hole?

From what you are describing the ejector isn't completely kicking the round clear. Things I would look at:

1. Take a look at the bolt again and make sure that the ejector pin hole is free of tiny brass shavings and clean. This is also a good opportunity to replace the ejector pin spring.

2. Any time you have any function problem with an AR that you cannot diagnose, you should immediately try the rifle with different magazines and ammo; because 99% of the time, that is the source of the problem.

Recently a saw a post of some Russian ammo where they missed cutting a taper on the extractor rim of the case during manufacturing. Not suprisingly, ammo caused problems. If you can try it with several different types of ammo and known good magazines, that can go a long way to reduce troubleshooting frustration.

 

[boostedtt91]

id try like suggested above. Try different ammo, magazine wouldn't really have to much to do with it ejecting i wouldn't think. Did you take your bolt apart and check your ejector?

Does it eject fine if you chamber a round and then pull the charging handle back to eject it?

 

[Will Lee]

Thanks Bartholomew & boostedtt91 for the input.

I did try different ammo and 2 mags from Bushmaster, no help.
Going back to the bolt and go through it as y'all suggested.
Round eject okay manually.

Will post results

Thanks Again
Will

 

[CTS]

Take a look at the gas rings on the bolt and make sure they are clean and not damaged or bent. If rounds eject OK manually, could be the bolt is losing gas pressure and not opening far enough to cause ejection.

 

[UtopiaTexasG19]

Bravo Company makes a enhanced extractor replacement kit which includes a rubber like o-ring to go around the spring and assist it with more tension. For 5 bucks it might be worth a try if you cannot come up with another answer to the problem.
http://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm extractor spring upgrade.htm

 

[Bartholomew Roberts]

Slappy brings up a good point. You may be short-stroking in a really bad way. One more thing to look at.

 

[Will Lee]

Bravo Company makes a enhanced extractor replacement kit which includes a rubber like o-ring to go around the spring and assist it with more tension. For 5 bucks it might be worth a try if you cannot come up with another answer to the problem.
http://www.bravocompanyusa.com/BCM-E... upgrade.htm

Thanks for this link, will give it a try

 

[Bartholomew Roberts]

Bravo Company makes a enhanced extractor replacement kit

Not a bad idea and a cheap upgrade; but I doubt it is the problem since it sounds like the rifle is extracting (pulling the empty case out of the chamber) just fine. It isn't ejecting completely though.

 

[Will Lee]

Take a look at the gas rings on the bolt and make sure they are clean and not damaged or bent. If rounds eject OK manually, could be the bolt is losing gas pressure and not opening far enough to cause ejection.

Gas rings look fine; i can feel resistance to movement of the bolt which i think is the tension of the gas rings. All ports and tubes are clean. Is it possible that the gas port in the barrel is fouled? Guess I need to figure out how to check that port..

 

[CTS]

I have never seen the port in the gas block (sight base) fouled or pluged. It couldn't hurt to look at the chamber end of the gas tube, maybe run a pipe cleaner thru it, I doubt this is the problem but, can't hurt to check it. Maybe even blow some compressed air thru it from the chamber end. I guess you would know if it had been dropped or anything that may have dented the gas tube, if unsure, you could remove the hand guards and have a look. I know it is doubtful, would have had to be something that just happened to go in thru one of the top cooling ports. Pretty unlikely if the hand guards aren't damaged.

 

[MythBuster]

To check for short stroking fire about 8 rounds single loaded. If the bolt locks back each shot your gas system is fine.

 

[Will Lee]

I have never seen the port in the gas block (sight base) fouled or pluged. It couldn't hurt to look at the chamber end of the gas tube, maybe run a pipe cleaner thru it, I doubt this is the problem but, can't hurt to check it. Maybe even blow some compressed air thru it from the chamber end. I guess you would know if it had been dropped or anything that may have dented the gas tube, if unsure, you could remove the hand guards and have a look. I know it is doubtful, would have had to be something that just happened to go in thru one of the top cooling ports. Pretty unlikely if the hand guards aren't damaged.

Well Slappy, the barrel gas port is clean and the gas tube is clean. All back together now, time to shot it and see if still has the ejecting problem. Will let y'all know. Thanks tons for the help and advise guys.

Will

 

[Will Lee]

To check for short stroking fire about 8 rounds single loaded. If the bolt locks back each shot your gas system is fine.

Roger That

 

[Will Lee]

To check for short stroking fire about 8 rounds single loaded. If the bolt locks back each shot your gas system is fine.

fired a few single round this afternoon. Rounds ejected okay but bolt never locked back

 

[MythBuster]

If it locks back when you pull the charging handle back but it does not lock back during live fire you have a problem with your gas system.

Look at the top of the bolt. There are two Allen screws. Make sure they are tight.

 

[Bartholomew Roberts]

Well, sounds like we are closer to solving the problem anyway. We know the rifle was working well and now its not, so let's work through the gas system again.

Check the gas rings by removing the cam pin from the bolt carrier and standing the bolt carrier on the bolt face. The gas rings should provide enough friction to keep the bolt from collapsing completely (this is a little more strict than the military recommended procedure to troubleshoot gas rings, but can help sort out a borderline issue).

Check that the gas key on the bolt carrier is clear of obstructions by running a pipe cleaner through it. Check to see if the gas key screws are loose or have moved from their staked position. Look for any obvious gaps between the gas key and the bolt carrier.

Check that the gas key slides onto the gas tube freely in the upper receiver.

Check your front sight base and the pins/screws in it to make sure your front sight base isn't loose/shifted to where it is partially blocking the gas port.

If all of those are good and you've still got a short-stroking problem, then I'd replace the gas tube with a new tube on the 1 in a million chance you've got calicum carbonate buildup in there (easier/cheaper than cleaning it out).

And of course, verify that the problem happens with more than one type of ammo (and use brass-cased domestic ammo to test it), just to rule out the possibility of a weird pressure curve/steel case/foreign ammo, etc.

 

[Will Lee]

Well, sounds like we are closer to solving the problem anyway. We know the rifle was working well and now its not, so let's work through the gas system again.

Check the gas rings by removing the cam pin from the bolt carrier and standing the bolt carrier on the bolt face. The gas rings should provide enough friction to keep the bolt from collapsing completely (this is a little more strict than the military recommended procedure to troubleshoot gas rings, but can help sort out a borderline issue).

Check that the gas key on the bolt carrier is clear of obstructions by running a pipe cleaner through it. Check to see if the gas key screws are loose or have moved from their staked position. Look for any obvious gaps between the gas key and the bolt carrier.

Check that the gas key slides onto the gas tube freely in the upper receiver.

Check your front sight base and the pins/screws in it to make sure your front sight base isn't loose/shifted to where it is partially blocking the gas port.

If all of those are good and you've still got a short-stroking problem, then I'd replace the gas tube with a new tube on the 1 in a million chance you've got calicum carbonate buildup in there (easier/cheaper than cleaning it out).

And of course, verify that the problem happens with more than one type of ammo (and use brass-cased domestic ammo to test it), just to rule out the possibility of a weird pressure curve/steel case/foreign ammo, etc.

Thanks very much for the procedure, i will go through it step by step. Headed to the lease in the morning mgiht take it with me and work on it between hunts. Will let you know the out coming when I get back.

Again thanks alot..
Will