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9/22/2017 12:11:25 AM
Posted: 12/18/2005 5:25:43 PM EDT
Hi group,

I've got a 16" RRA (now 11.5") and occasionly have failures to feed, always when hasn't been cleaned for ~500 or so rounds, generally from a mostly full mag. I shot yesterday and it worked fine. When I left the range I had the bolt/carrier locked back. When I got it out today to put it away, I hit the bolt release, and nothing. Bolt didn't move a bit. I worked the charging handle back and forth and got it to go. I removed the upper and could see where the cam pin was scraping quagbeatum from the slot where it rides. I'm pretty sure that this build up has been causing the extra drag and my functioning problems. Yes, I know that I can just make sure to clean it more often, shoot cleaner ammo etc., but I view this as more of a working rifle, and a gun that takes itself out of the fight every 400~500 rounds just isn't acceptable. The key and pin measure ~.402", and the slot that they ride in seem to measure about .415", but I've only been able to measure from the back side of it. How much clearance should there be in this area? I haven't been able to find the appropriate drawings for the upper (yet). Thanks for your time, and have a nice day.

Stych
Link Posted: 12/19/2005 4:28:42 AM EDT
The Key can bind up both on the four corners of the two flats, and it can bind up on the bottom of the charging handle.

If needed, take a file to the edges of the flats if you get biding here, or if the key is binding up in the charging handle (it's new key or charging handle time).

P.S. Pull the buffer and check the recoil spring. Could be that you have an end of wind bur that is scrapping down the inside of the tube. If yes, then use the file to remove the bur.
Link Posted: 12/19/2005 3:27:02 PM EDT
Thanks for the reply. The buffer spring looks smooth, as do the sides of the pin & key. I'm reluctant to remove any more material until I can find out what the revelant dim's should be. If anyone knows these, or can direct me to the appropriate drawings, that would be great. Thanks,

Stych
Link Posted: 12/19/2005 4:23:42 PM EDT
[Last Edit: 12/19/2005 4:24:25 PM EDT by Dano523]
Did you check the edges of the cam for binding in the slot track?

Is there any wear marks on the bottom slot of the charging handle (key should never touch the top slot in the charging handle).

Does the cam have full movement in the carrier, hence it will move forward enough to get in line with the sides of the key?

Lastly, check the back of the disconnector for a dent/white line behind the hook. Could be that the hammer is binding on the disco as the carrier moves back, and this binding could be causing failure to complete stroke, or the back stroke binding.
Link Posted: 12/21/2005 8:09:43 PM EDT
Originally Posted By Dano523:
Did you check the edges of the cam for binding in the slot track?

Yes. They bind from the gunk when dirty. OK when clean

Is there any wear marks on the bottom slot of the charging handle (key should never touch the top slot in the charging handle).

No, no contact there.

Does the cam have full movement in the carrier, hence it will move forward enough to get in line with the sides of the key?

Yes, full movement, and when dirty, both sides of the pin scrape the slot about the same.

Lastly, check the back of the disconnector for a dent/white line behind the hook. Could be that the hammer is binding on the disco as the carrier moves back, and this binding could be causing failure to complete stroke, or the back stroke binding.

No interference from the disco.

My guess is that the slot is just a bit tight, or that I'm expecting it to do something that it won't. Thanks for your help, and your patience.

Stych
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