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Posted: 12/8/2003 1:58:31 PM EDT
I redrilled/opened up the gasport on a project barrel of mine and after the process there seems to be a small amount of burrs on the lands of the barrel. I tried a bore paste to see if that would wear the burrs out a bit and it did, but is still noticable. Using a .22 cal jag and a patch there were no hang ups or noticable change in resistance at the point of the burrs.

Need opinions on the shootability of this barrel. Not to worry about accuracy. It is obstruction enough to be considered a danger.

TIA
Link Posted: 12/8/2003 3:24:51 PM EDT
Most new barrels have a bur at the gas port that is just cleaned/shot out once the barrel is fired. So as far as your bur at the gas port, don't worry about it. FYI: If you opened the gas port to much, your going to have problems with the action cycling too fast/strong.
Link Posted: 12/8/2003 4:31:07 PM EDT
Dano, Thanks for the fast response. For the first few rounds, I'll sand bag it and and use my remote trigger system (rope). As for the gasport being opened too much, I have made an adjustable gas block. Part of the reason I bore the gasport out, is to see how effective the gasblock design is.
Link Posted: 12/8/2003 5:41:26 PM EDT
Start off with the block shut down, then slowly open/test the rifle. Once you get to the point that you are getting 7-10 foot ejections, then loctite the screw down. If you go for a dribble effect setting, then as the chamber/rifle starts to foul, the rifle will start to jam. If your looking for a the cases to be ejected at your feet, start with the gas system set to eject around 10', lock the screw, then start to trim winds off the ejection spring. This will insure that the action is cycling at the correct speed, and the spent cases will stay on the bolt face a little longer to be ejected during the forward stroke of the bolt and not at the buffer stall. At no time allow the gas port (oversized) to left wide open, even during any advice conditions. The excess speed of the carrier/buffer coming back is going to destroy the back of the receiver extension. If not caught in time, such as using a full length stock where your shoulder may be holding the butt stock in place (cracked receiver extension tube end), then the butt stock slips back away from the receiver extension, the carrier key is going to crack the back of the lower receiver off as the carrier/key tries to shoot out the back of the receiver, since the buffer is not being limited in it's rearward travel. P.S. Why did you enlarge the gas port any way? Was there a cycling problem with the rifle/barrel, or is the barrel/port just oversized to test out a new gas block design?
Link Posted: 12/8/2003 9:37:18 PM EDT
223Rem, Short of the barrel being fully blocked a "remote trigger system" shouldn't be necessary. [:)] I had a client gun come in with far too large of a gas port. The first round out of the barrel, with its freshly bushed gas port, caused the piece to shortstroke as did every other round. Inspection showed that the bottom of the bushing had protruded into the bore for the first shot. That first shot closed the end off on the bushing effectively shutting it down. No, I had not been the one to install the bushing and I now check that little detail prior to test firing. Inspections at my old employer showed that the burr on the gas port does not disappear with shooting. We used a borescope to inspect a freshly drilled barrel (the gunsmith's race gun) and periodically thereafter as he used it through the seasons. The burr did get smaller and noticeably smoother but it was still evident. Part of the smoothness came from the buildup of jacket material on the burr. Hardly a comprehensive test but we did the best we could there.
Link Posted: 12/9/2003 5:09:27 AM EDT
Dano, Basically just messing around right now. I have so many additional part laying around I figured "what the hell" and "what if". Tweak, My biggest concern with the oversized gasport is having the bullet's jacket sheering off and eventually clogging the port or even have the fragment come back into the action. Should this be a concern? TIA
Link Posted: 12/9/2003 7:53:11 PM EDT
Originally Posted By 223Rem: Should this be a concern?
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Not really as the jacket is snagging on the burr [b]prior[/b] to the gasport. Most gas ports have burrs and I [i]think[/i] this is why NM barrels are required to have the gas port centered in a groove. I knew a guy that drove a lead slug into the barrel under the area of the soon to be gas port in order to prevent burrs. He swore by the procedure. The machinists I've talked to swear by sharp bits and proper speeds and feeds.
Link Posted: 12/20/2003 12:56:02 AM EDT
[Last Edit: 12/22/2003 6:40:17 AM EDT by mjcarter]
Gas ports have to be REAMED to correct size after drilling to ensure that no burrs are present. You will not find burrs in the gas ports with barrels fit and chambered by reputable manufacturers and 'smiths such as Kreiger Bbls., Frank White, John Holliger, etc. BTW, the gas port can be easily located in a groove in a four groove barrel, but in a six groove, it's not as easy.
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