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-   -   AR in 6.8 SPC not chambering well (http://www.firearmstalk.com/forums/f20/ar-6-8-spc-not-chambering-well-80538/)

jspruell 01-06-2013 08:54 PM

AR in 6.8 SPC not chambering well
 
I have a palmetto state 6.8 spc and when I chamber the first round and most consecutive rounds, the bolt isn't fully engaging and fully closing. I'm using magpul poly mags with hornady ammo. Any suggestions?

oldpapps 01-06-2013 10:16 PM

Is the weapon 'NEW'?
Has it ever been fired?
Is the bolt/BCG running 'wet'?
Has the chamber been cleaned out?
Have you checked the 'key' on the BCG to see that it is on tight (and staked)?
Will the bolt cycle closed/open with little to no effort?

First things first. Break it open and look at the BCG. Check the 'key' (that snout thing that rides on top of the Bolt Carrier). It must be solidly screwed on and most (including me) thinks the metal holding those screws should be bent into the screw heads). If that is a go, move on.
Slip everything back together. Pull the operating handle back. Is there anything other than the resistance of the buffer spring? If not smooth and easy, find out why.
Drop the bolt. It is supposed to be released and fly back into battery (closed). Did it?
Run a patch down the bore and then clean the chamber. Look at the lugs on the rear/face of the barrel and front of the bolt. If all looks good, Oil the BCG. I use Mobile One, you can use what you like but the bolt needs to be wet with oil. Dry cycle the action several times. Turn the safety on. Load a mag, turn the safety on. Insert the mag. Turn the safety on. Now this is important, make certain that the safety is on and keep your finger out of the trigger guard. Cycle the bolt one time. Drop the mag. Look to see if the bolt is locked (all of the way forward). Keeping your fingers away from the trigger, cycle the bolt again to remove the round.

If at any point in this, a problem was detected. STOP AT THAT POINT.
This is better performed at a firing range and/or with non functional test ammunition.

I don't like to suggest to a person that I can't watch, to actually load a weapon that I have not evaluated. It is scary for me to think about.

This was not to belittle anyone, but to emphasize the importance of being very, very safe. The statement 'not chambering well' is wide open for interpretation.

jspruell 01-07-2013 01:21 PM

Quote:

Originally Posted by oldpapps
Is the weapon 'NEW'?
Has it ever been fired?
Is the bolt/BCG running 'wet'?
Has the chamber been cleaned out?
Have you checked the 'key' on the BCG to see that it is on tight (and staked)?
Will the bolt cycle closed/open with little to no effort?

First things first. Break it open and look at the BCG. Check the 'key' (that snout thing that rides on top of the Bolt Carrier). It must be solidly screwed on and most (including me) thinks the metal holding those screws should be bent into the screw heads). If that is a go, move on.
Slip everything back together. Pull the operating handle back. Is there anything other than the resistance of the buffer spring? If not smooth and easy, find out why.
Drop the bolt. It is supposed to be released and fly back into battery (closed). Did it?
Run a patch down the bore and then clean the chamber. Look at the lugs on the rear/face of the barrel and front of the bolt. If all looks good, Oil the BCG. I use Mobile One, you can use what you like but the bolt needs to be wet with oil. Dry cycle the action several times. Turn the safety on. Load a mag, turn the safety on. Insert the mag. Turn the safety on. Now this is important, make certain that the safety is on and keep your finger out of the trigger guard. Cycle the bolt one time. Drop the mag. Look to see if the bolt is locked (all of the way forward). Keeping your fingers away from the trigger, cycle the bolt again to remove the round.

If at any point in this, a problem was detected. STOP AT THAT POINT.
This is better performed at a firing range and/or with non functional test ammunition.

I don't like to suggest to a person that I can't watch, to actually load a weapon that I have not evaluated. It is scary for me to think about.

This was not to belittle anyone, but to emphasize the importance of being very, very safe. The statement 'not chambering well' is wide open for interpretation.

I oiled the bolt well and it seemed to be a fuz better but still not functioning 100% of the time. I have since taken the gun to the gs that built it. He has a suspicion that the extractor spring could be too tight. Does that sound possible. I know very little about the AR platform as far as detailed workings of the small parts.

oldpapps 01-07-2013 02:48 PM

There are many possibilities.

When you explained your concerns to the GS and he/they gave their hands on evaluation, are they going to clarify the spring problem they determined to be the problem?

Often, brand stinking new mechanical devices just have very tight tolerances. I kind of like that. I would rather work the meshing parts together than to have them slopping about. If all of the safety concerns are covered, lub it up and shoot a few around. See if anything improves.

Two or three years ago I put together a 20in Bull barreled RR upper on a Mega lower with a parts kit and a 'Full Auto' BCG (it is a weight difference - doesn't make anything fire full auto). It was very tight and sluggish for 40 or more rounds. Manually extracting a loaded round was a total pain. With only lots of Mobile One and repeated cleanings, it began running like a clock. I was able to make a hole in paper targets at a hundred yards. That doesn't sound like much but after twenty rounds all cut a single hole, further shooting is into a blank area of the target. Might as well be shooting off of the target :D I miss that weapon :(

The point is tight is better with new. Let it seat together.

jspruell 01-07-2013 02:53 PM

Quote:

Originally Posted by oldpapps
Is the weapon 'NEW'?
Has it ever been fired?
Is the bolt/BCG running 'wet'?
Has the chamber been cleaned out?
Have you checked the 'key' on the BCG to see that it is on tight (and staked)?
Will the bolt cycle closed/open with little to no effort?

First things first. Break it open and look at the BCG. Check the 'key' (that snout thing that rides on top of the Bolt Carrier). It must be solidly screwed on and most (including me) thinks the metal holding those screws should be bent into the screw heads). If that is a go, move on.
Slip everything back together. Pull the operating handle back. Is there anything other than the resistance of the buffer spring? If not smooth and easy, find out why.
Drop the bolt. It is supposed to be released and fly back into battery (closed). Did it?
Run a patch down the bore and then clean the chamber. Look at the lugs on the rear/face of the barrel and front of the bolt. If all looks good, Oil the BCG. I use Mobile One, you can use what you like but the bolt needs to be wet with oil. Dry cycle the action several times. Turn the safety on. Load a mag, turn the safety on. Insert the mag. Turn the safety on. Now this is important, make certain that the safety is on and keep your finger out of the trigger guard. Cycle the bolt one time. Drop the mag. Look to see if the bolt is locked (all of the way forward). Keeping your fingers away from the trigger, cycle the bolt again to remove the round.

If at any point in this, a problem was detected. STOP AT THAT POINT.
This is better performed at a firing range and/or with non functional test ammunition.

I don't like to suggest to a person that I can't watch, to actually load a weapon that I have not evaluated. It is scary for me to think about.

This was not to belittle anyone, but to emphasize the importance of being very, very safe. The statement 'not chambering well' is wide open for interpretation.

It has been fired about 60 rounds. So pretty new.

jspruell 01-07-2013 03:03 PM

Quote:

Originally Posted by oldpapps
There are many possibilities.

When you explained your concerns to the GS and he/they gave their hands on evaluation, are they going to clarify the spring problem they determined to be the problem?

Often, brand stinking new mechanical devices just have very tight tolerances. I kind of like that. I would rather work the meshing parts together than to have them slopping about. If all of the safety concerns are covered, lub it up and shoot a few around. See if anything improves.

Two or three years ago I put together a 20in Bull barreled RR upper on a Mega lower with a parts kit and a 'Full Auto' BCG (it is a weight difference - doesn't make anything fire full auto). It was very tight and sluggish for 40 or more rounds. Manually extracting a loaded round was a total pain. With only lots of Mobile One and repeated cleanings, it began running like a clock. I was able to make a hole in paper targets at a hundred yards. That doesn't sound like much but after twenty rounds all cut a single hole, further shooting is into a blank area of the target. Might as well be shooting off of the target :D I miss that weapon :(

The point is tight is better with new. Let it seat together.

Thank u for ur help. I will post u an update when I get it back to the bench and paper!!

oldpapps 01-07-2013 03:07 PM

60 rounds, I would think that it should be getting seated well. Did/is the GS going to do anything with the extractor spring?

I didn't get to build a 6point8. I made the choice to go with a 300 Blackout and had a good time with it. Then made the mistake of saying yes to one of my son-in-law's brother and he bought it :( Now I have none :eek:
With the current frenzy, it will be a bit before I put together another AR.
All of the PSA stuff I have bought has been good and I suspect their 6point8 uppers are just as good of quality.

The 6point8 is a more intense round than the 300 Blackout and maybe a bit more than the 223/5.56, so I would think it would begin seating soon. 60 rounds, hum. Your loads or factory?
There are some trick to speed up the seating process. I have never used them on an AR, but several times on 1911s. I will refrain from going further here.

Quentin 01-07-2013 06:23 PM

oldpapps has given you a lot of excellent advice, js.

I also think 60 rounds should be enough to smooth out the action a bit. With the rifle empty and no magazine work the charging handle all the way back then don't let go, instead ride it back forward slowly and see if the bolt will lock into battery. Let go and push in the forward assist to make sure the bolt locks in fully. In a smooth action that's not chambering a round the FA isn't needed to lock the bolt lugs even if you ride the action back into battery. Repeat this many times and feel for smoothness as you work the charging handle. You should be able to tell if something's not right.


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