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hayseed
01-09-2008, 02:09 PM
While waiting for my first real long range benchrest rifle to get finished, I've been trying to get reloading gear and components squared away.

Bruno's recently supplied me with 400 6 BR Lapua brass. First Lapua brass I've ever handled - quite a nice treat. I've been looking them over closely.

Also recently, I aquired Sinclair's 09-900 electronic neck mic tool. The one with the Fowler digital gauge and ball type anvil. Allows you to check different points from the mouth back toward the shoulder. The spindle doesn't have a tapered tip, but I can still check into the neck close to 3/4 of the way. Fowler gauge reads to 5 places, which they admit is pretty optimistic. I've been checking it against my good old .0000 outside mic and am pretty confident to 4 places with the Fowler though.

The wall thickness variation in any one case appears to be about .00065 to
.00080, using the 5th digit. Variation from case to case seems to be only slightly larger - maybe .001 total range (.0130 +/- .0005). I've only checked a dozen cases so far, but I'm finding hard to define groups. What variation between cases I can find seems awful small, especially in light of the individual case run-out.

So if you're sorting cases by neck thickness, what are your parameters?

Also, I noticed that the neck thickens from mouth to shoulder. Although I can't measure right up to the neck/shoulder junction, I estimate nearly .001 taper. My chamber will be the .272 no turn scheme. I hope not to use an expander ball when sizing. Will I need to use something like the Expandiron after sizing to square this dimension for consistant grip?

Thanks for any help or comments. Dick

MARKS
01-09-2008, 06:57 PM
Hayseed,
I shoot a 6BRX (6BR IMP) for long range. All I do to the brass is sort by weight, looking to get a group in 0.5 gr range. The Lapua 6 BR brass is so good, that is all that is needed. The last I weighted, came up with 2 nice 0.5gr groups

Mark Schronce

hayseed
01-09-2008, 08:27 PM
OK Mark, thanks a lot for the advice. If they're good enough for you as is, then they're plenty good enough for me. I will weigh them as you suggest. I thought that I might be trying to split hairs finer than necessary.

The thickening neck toward the shoulder is not a concern then either in the no turn neck ?

MARKS
01-11-2008, 12:41 PM
hayseed,

Alot of the 600 yd Benchrest shooters are shooting No Turn necks on there 6BR and 6BR IMP's. I have not had a problem with flow into the neck. The other thing,I don't open the flash hole, leave it as is.

I run the bullets (Berger 105 VLD's) thru a David Tubb's bearing surface compairtor, sort to 0.001" lots. then group in 0.003" groups

Then loaded rounds are run thru a runout gage. smallest are record, the rest are sighters.

Mark Schronce

hayseed
01-11-2008, 08:34 PM
Great, Mark. Thanks again.

Octopus
01-14-2008, 06:45 PM
Mark,

Why use anything other than the best for a sighter?

Octopus

MARKS
01-15-2008, 11:52 AM
Octopus,

All of these rounds are good. I could shoot these without doing anything. I is just a mine thing fo me. I feel better doing it.

Mark Schronce

hayseed
01-17-2008, 01:38 AM
Ok, I've been sorting and measuring like crazy. I took Mark's advice and weight sorted brass. I ended up with 2 pretty equal sized groups about 1/2 gr. apart.

For the heck of it, I did also end up with one small group of brass that was sorted by neck thickness previously. Variance in any one case and also within the group was about .0005. I think I'll just set them aside for experiment once I have loads ironed out better.

I also sprung for one of Tubb's comparitors. Really a nice repeatable tool. Worked quickly through what bullets I have.

I was wondering if there is any rule of thumb you guys use when pairing the brass and bullets up? For instance, would the bullets with the longer bearing surface tend to match up with lighter group of cases? Vice-versa? I suppose you just have try them in your rifle, but thought I'd ask...

Thanks, Dick

Octopus
01-17-2008, 07:28 AM
Over the past 3 months my shooting buddies and I have been weighting and measuring bullets. Mostly we have came to the conclusion that we need better scales.

The Berger bullets have been near perfect. That is they weigh and measure better than we seem to be able to check with our tools. We all three had the same general result. The Berger Match bullets came out better than the custom hand made bench rest bullets we checked. (And we checked bullets from several of the better known bullet smiths.)

After we saw the results we started shooting the Bergers and found them to be as good, and in some cases better, that our past favorite bullets. We are now using these bullets in our 6 PPC BR rifles, and in our 25 and 6.5 long range rifles. We are still early in the "how they shoot" evaluation but so far they are doing better than our past favorites.

Try a box of the Bergers on your Tubbs tool and see how they measure.