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ten2six
Senior Member
USA
243 Posts |
 Posted - Nov 06 2009 : 11:57:00
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I've got a friend who will only put his rifle bullets into the chamber, one at a time, and always in the same orientation. He lightly scores the base of the bullet with a file to put a line he can align in an upward vertical position. He also uses this when he is working the brass in his press, always having the brass in the same orientation, from neck sizing to seating.
I chuckle every time I think about it, but maybe someone here knows if this is just a superstition or has some merit to it.
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"Chances are, when we meet intelligent life forms in outer space, they're going to be descended from predators."
- Michio Kaku |
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Bart B.
Senior Member
364 Posts |
Posted - Nov 06 2009 : 13:55:39
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Among the top scoring competition shooters, it's a well known fact that out of square case heads cause accuracy prombles. If his rifle's bolt face isn't perfectly square with the chamber axis, indexing loaded rounds as he does will help.
Few folks are accurate enough to notice any difference even with tgop quality match rifles, but it's not superstition. |
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F. Guffey
Senior Member
USA
322 Posts |
Posted - Nov 06 2009 : 16:20:23
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Finding someone that can not measure case head cant caused by a bolt face that is not square with the receiver is easy when you find someone index the case in the chamber based on the last firing. It would require a fixable reamer to ream a chamber out-of-round, I do not know how they did it but I reamed a custom 25 cal barrel to 257 Weatherby, after completion I ran a spot on indicator on the chamber, the reamer lacked .011 cleaning the chamber, I ask them why the barrel was removed, they did not know, they said the barrel was removed because it would not shoot?
Cases, when fired, if not measured for cant as in not being able to stand up straight could lead some to believe, when measured for run out, the case is OK. I pose the question 'ONCE' "When measuring a case for run out is the case standing or laying down"?
F. Guffey
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Paul B
Advanced Member
1681 Posts |
Posted - Nov 06 2009 : 18:03:45
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It's a technique called indexing. A lot of cast bullet shooters do it where they put a tiny scratch in the mold, use one cartridge case neck sized only with a small groove filed on the rim of the cartridge case. The case is primed at he rnge, powder charge carefully thrown, the bullet with it's index mark lined up with the witnes mark (grooved rim) on the case and very carefully loaded into the chamber with the witness marks always as close as possible in the same position for every shot. It is belived that this will eliminate sore of the margin of error built into the rifle and shooter's quirks.
Does it work? Yup! One of my cast bullet riles is a Winchester M70 in .308 Win. cast bullets loaded conventionally and fired at 200 yards do about 3 to 3.5 MOA and 5 MOA at 300 yards.
With everything lined up so that repeatabilty is almost as perfect as I can make it, 200 yard groups run 1.5 MOA and 300 yard groups 2.5 MOA. At least in that scenario, yes I think it can make a big difference.
I've just started playing with a Browning B-78 single shot in 30-06 that is MOA at 100 yards with jacketed bullet ammo. I'll be workin up a load using the indexing method with a 220 gr. cast bullet using two methods, both with the indexing. One will be done as described above and the other with the bullets breech seated where you use a tool that holds just the bullet and insert it into the chamber. Then you load a charged cartridge to fore the shot. I've gotten fair results from a Ruger #1 in 30-06 loading that way, but it's never been all that good a shooter with anything.
The only problem I see in using the index method is with a bolt action, the cclosing of the bolt may iduce a certain margin of error.
I don't see any problem with using the method if it kames your friend think it improves his groups. The only way to tell is if he loads conventinally and shoots a few groups then does the same thing with his "indexed" loads.
Paul B. |
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ten2six
Senior Member
USA
243 Posts |
Posted - Nov 07 2009 : 21:40:48
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Thanks....I feel really bad now...it even has a name. I threw him so much sh#@, because he looked so comical doing it. Granted, he and I are in that age bracket where we need reading glasses and extra light to do just about anything. He kept holding his rounds out at full arm length, then sticking his nose down near the chamber as he fed rounds because he had forgotten his glasses.
It sucks growing old...but I guess the alternative is even worse...as the saying goes. ; )
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- Michio Kaku |
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Call it superstition??
