barrel timing Q's

[pavedave80]

Hi,
Just got the threads on my DCI Lar receiver chased and now it times to about 9:15 pm pst. Now I find touch marks where the chamber end of the barrel is hitting the rail end of the receiver. It caused two small burrs which I carefully removed. It now rides on the top of the receiver where there is a small section of metal in the way.

Here is the Q. What gap should I have between the chamber end of the barrel and the ramp plane on the receiver after final timing? Should there be any gap at all?

Second Q. I seem to have sone distortion on the chamber end of the barrel. Kooks like where the bolt has slammed in to the barrel. Is this bad? Does this surface need to be smooth?

Thanks for the help,
Dave

[rwwje]

As I understand your situation, the breach end of the barrel is contacting the secondary breach face of the receiver at 9:15 (Imbel barrel?). To be able to to time to TDC, you will need to remove 0.015" from either the breach end of the barrel (using a file) or from the secondary breach face of the receiver (using an end mill or drill press/stone). This has been a problem with later batches Imbel receivers and usually with Imbel barrels. But, 0.015" is a little more than I would like to remove from the end of the barrel, especially if the receiver is the out of spec part (the rule is to modify the less expensive part). The breach end of the barrel can be in contact with the secondary breach face of the receiver as long as you can get to TDC without using excessive torque (say, more than 200 ft-lbs), or it can clear by a few thousandths. As far as the distortion on the end of the barrel, I can't recommend anything without seeing it, but the general rule would be to reshape it to the original contour (did you have the bolt in the receiver while torquing the barrel? If so, the extractor may have caused the distortion........). Hope I didn't miss the point of your questions, I'm somewhat uncertain as to the exact nature of the issue(s). Thanks.

[pavedave80]

rwwje,
Thanks for the reply. To answer your first question; I think the breach end of the barrel is contacting the secondary breach at the 12 O'clock position when looking at the receiver muzzle to butt. (front to back) To clarify the situatiion: Imbel barrel, DCI receiver, clean threadsno, I did NOT have the bolt in the receiver( as no insult was meant, no insult taken, I may be new,But I'm no THAT new) The deformation i saw corresponded with the location of the ejector claw. It is kind of wavy with a well defined area. I also noticed a couple of burrs on the barrel threads which I honed off. I guess I'll have to find out what is square and what is not. After final timing, what knid od gap should I see at the primary breach face at the barrel nut.

Thanks,
Dave

[steveo539]

Dave,
See my post below with subject line "barrel timing" It has some of the same questions/answers. I've got a couple other barrels at home. I could bring them in to work and you could bring your receiver over and see if they fit differently. Not wanting to give them up, but it might be an easy way to narrow down the problem. I might be able to help you shave a few thou off the barrel too if required.

Steve

[rwwje]

Originally posted by pavedave80
rwwje,
.................. After final timing, what knid od gap should I see at the primary breach face at the barrel nut.

Thanks,
Dave

None, this is the point of contact/"stop"/"crush" between barrel shoulder (barrel nut?) and the receiver's front face (primary breach face), which allows (opposes) the typical 100 to 200 ft-lbs of torque applied to the barrel/receiver to bring the barrel to TDC from the 10:30 to 11:00 hand timed (initial contact) position.........if I understand the question. Thanks.