Problems with 6 Dasher

J

jliles

Guest
I have a 6 Dasher built on a Remington 700, Broughton 1-8" @24" throated for 107 MK. I was working up some loads last night with slight right to left mirage, with 0-2 mph winds.
All loads were shot at 200 yards off sinclair rest with edgewood rear bag. I started at 30.5 grains of RL 15 with bullets just kissing lands.
Problem: I could shoot a .5" - 3 shot group, and then the next group (same load) might be 2" group. It looked like something was broke!! I checked every screw, bolt, bedding, etc., with no luck. I moved up in ~.3 grain increments with no luck, seated bullet deeper by .005" with no luck.

Any ideas?????
 
jusk kissing might be your problem. try just in or just out, either one might do better then just kissing. 107 smk, i would favor out/jump a bit.
tom
 
What press/die set are you using and are you checking the OAL from the ogive of every round as it comes off the press? "Just kissing" is a pretty tight tolerance and with the set-up round "kissing" you can sometimes have full contact with some and a bit of a jump with others. My RCBS seating die will sometimes vary half a thousandths ± in a set of ten rounds. There are also occasions where the bullet doesn't seat perfectly straight in the case as it enters the die and, as a consequence, it can stretch one side of the case neck slightly as it fully seats, causing an uneven release.
One other thing I might want to look at is abandoning the three shot group method of load workup and rely on a ladder technique with a load variance of about 10% per round.
Those ideas may not help but if any of it does I wish you well at your next match.
 
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I would try jumping the 107 sierras. I have found that they have a very large baring surface variation. Jump them 20thou and if that doesnt look any better then try a different bullet. Thats what i would do, but i am just a nobody!! Lee
 
I'd check your scope. Sounds like it took a dump.

Greg
 
With tangent ogive bullets (SMK's, Scenars, Berger 108's etc) I've found it best to let them jump, .005"+. With the secant ogive bullets (VLD's) I've found the sweat spot to be from just touching to +.015" in the lands.

Try the 107SMK's just off the lands (no land marks) with RL-15 between 31.5 & 33.0 grains with CCI450's. My 6 Dasher load is 32.0 grains of RL-15, CCI450's, 105 Berger VLD's (Hunting Style) +.015" in the lands, Neck turned Lapua Brass & .002" neck tension.

It sounds like your load is just out of tune, the rifle is probably fine.
 
Your shooting a straight BR load...Try the 105/107/108 at 3000pfs or more...33.5 grs of RL 15 with 108's, jammed to a "square' mark will shoot...

Good luck..
 
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