View Full Version : Cop-Out Fix For Century Inch Receiver Misalignment Problem

June 23, 2002, 15:00
As reported elsewhere, my last pair of Century inch receivers had a problem with the casting where the gas tube nut enters the receiver is out of whack. Since the hole enters at an angle, this causes gas piston binding. My great idea yesterday, which took most of the day, was to get a length of 0.50" steel rod and turn most of the length down to 0.430" so that it will just fit into the gas tube. I bought a drill bit the diameter of the smallest part of the piston (where it slides into the receiver) and recessed the steel rod so the bit could be fixed into the end. I used set screws and locktite sleeve retainer to hold the bit in place. This morning I put barrel, gas tube, gas tube nut, and receiver together. Then I slid my special "tool" into the gas tube from the muzzle end and hoped that the drill bit would open up the receiver to relieve the gas piston travel. No such luck. I guess there was enough flex in the bit so that it wouldn't cut on the side. So I opted out with the simple, easy fix and used the ol' rat tail file. Seems to work, but not as sophisticated as I wanted. Oh well.

June 23, 2002, 22:13
Had to do the same thing to a Hesse R1A1 century contract receiver. Functions fine and after the refinish, look alright.


charlie echo
June 24, 2002, 12:43
Hey, Phred, I'm still bugged by the carrier not closing.
I found where it is stoppnig on the ejector block, and I'm not too happy about it pranging on there every time the action closes.

Did you relieve the carrier enough so the front contacts the breech? Did you have to grind on the piston?
I substituted a STG piston so I didn't have to grind on a US one, and it's not making contact now.
The second set at $129 were a little better than that first batch, but they still suck. And it wouldn't take the inch BHO.

June 24, 2002, 14:27
Charlie--in my case, failure of the bolt carrier to close had nothing to do with gas piston. It wouldn't close if you put the bare carrier (no bolt) in the bare receiver (no barrel, piston, or anything). Since the carrier is cheaper than the receiver, I milled (dremel works just as well as mill) a few thousandths from the tang that hangs below the carrier on the right side. Looking in through the left locking shoulder hole with a penlight I could see that this was the primary area of contact. After removing material from that tang I noted the carrier closed further, but not enough to satisfy me. Further observation showed that the grooves in the receiver for the horizontal tangs on the carrier were not cut far enough forward. The horizontal carrier tangs were stopping where the grooves ended. A bit of judicious trimming to the front of these tangs allowed the carrier to ride all the way home. Funny--the single problem of failure to close on the carrier was caused by two independent faults in the receiver--even though the faults were easily remedied. Now just hope your gas piston lines up in the receiver. Screw the gas tube nut into the receiver and slide the piston in. See if it is straight or cocked to the side. Next, worry about the geometry of the feed ramps, but don't get discouraged. We're working on the problems. Feel free to e-mail me if you need details.

charlie echo
June 24, 2002, 16:23
Thanks, Larry, I'll check all that stuff again.
I don't like too much sturm und drang mit der dremel, so I'll try my rat tail file in there. I had to file a bit on the frame lock lug to get it to close, and the piston lined up fine.
Now to see if it'll shoot...