View Full Version : Blt dia and gas check dia
05-29-2007, 03:20 PM
Awhile back I got a bunch of somebodys 311041's, lubed but without GC, sized to
.310. These shot well enough as was in 06 over 13 gr. of RD, but decided to gas check a bunch of them. Ran them with GC through a .311 Lee push thru die. Just loaded a batch of them, but have not been able to shoot any of them yet. Am wondering if anyone out there has tried similar with body size a bit smaller than the GC. Seems to me that a check that is a bit larger ought to be a fouling scraper. Then again, a lot of things that to me seem logical some how or another just don't necessarily seem to be so in the minds of others. Guess thats what makes a horse race. Anyhow, if anybody else has tried this and has any results-pro, con, or otherwise, I would be interested.
Thanks in advance to all who respond to this thread.
05-29-2007, 05:54 PM
No problem, if you have been shooting 311 before with the same brass and gun. ... felix
05-29-2007, 06:18 PM
I've had that situation, though I think it happened for a different reason. The main issue was that when I seated the bullets the oversized gas check reduced the neck tension, which I didn't want to have happen. How big a deal all this is depends on how hard your case necks are - I seem to recall mine were freshly annealed. Aside from lack of neck tension there's a possibility of increased bullet runout.
05-30-2007, 04:21 AM
You have to remember that when the rubber meets the road, your check will be the same size as the bullet body as it passes into the "ultimate" sizer. (your bore)
In my opinion, the scraping action of a GC is over rated. I can site several reasons for my opinion with no coppering being the biggest one. If it aint coppering when under pressure, then there is little friction between it and the bore.
05-30-2007, 12:09 PM
I've done it. Grumpy's point about neck tension is well taken, but I don't think it applies when the difference is only a thou. I know nothing about "scraper action, but it's a useful trick with bullets that are just a hair small. I see a noticeable improvement in groups of bullets that are .311 when I want .312 when I GC to .312 or .313 even though the sizer does not touch the body.
05-30-2007, 12:17 PM
Depends upon obturation of everything involved, like boolit, brass, barrel, and action. Hopefully, only the boolit retains some of the obturation(expansion), and enough of it to maintain a 100 percent gas seal via its travel throughout the entire barrel. It appears the seal is being lost in this particular instance. ... felix
05-30-2007, 12:29 PM
Well, now that I have these words of wisdom, I am about as dumb on the subject as when I brought it up. However, I much appreciate the thought(s), logic, and theory that went into the replies. If it quits raining in Ne. long enough for me to get to the range in the next few days will report the results of my testing. While the factor of neck tension had run through my feeble goard, I also did not feel that a thousands of an inch would be appreciable. It did however remind me that it was probably time to consider annealing a bunch of brass that is long overdue.
Many thanks guys!
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