O.k. The new Forster dies are here for my 6.5-284, and I've got them set up.
However (always a however) after resizing some cases the neck O.D. is .2945-.295 the I.D. .260. When I seat a bullet the neck O.D. is still .295. The rifle has a .296 neck in it so my question is do I have enough clearance at .295 or do I need to polish down the expander ball acouple of thou. Also is that enough neck tension or am I likely to run into problems there?
Thanks for any help
Ignorance can be treated with education, sadly there is no cure for stupidity.
the 6mm ppc shooters a few years back use to shoot with .001 i think now they use even less.i just had HART do some accuracy work and rebarrel my rifle in 338 RUM i ask about a tight neck .he said don't do it.he was right it shoots so good it's up to the shooter how good it shoots.i can get .208 for 3 shot groups at 117 yards.i ask sinclair about 3 shot groups vs 5 shot groups they said shoot 3 to test the load and 5 to test yourself.my mcmillan 50 bmg has a standard neck and it is a world class shooter.i was told that the 6 mm ppc will shoot with a tight neck because it has almost no recoil.that a gun with recoil does not need a tight neck.my info came from sinclair international and R.W.HART.go to www.benchrest.com check out the forums they cover benchrest shooting where you will find tight neck info and shooters.
The neck tension of 4 thou is plenty. If you can't wiggle the seated bullets by hand, good to go. This is a match rifle so the ammo will not see any abuse.
I prefer to have 2 thou of clearance from the loaded neck to the chamber wall. Others have used less but I am a chicken that way.
I bet your ability to measure is to around 2 thou error, maybe more. Recheck all measurements with a guage that can measure to within 1/2 thou. With clearances this tight, you just have to know.
When you fire the ammo, the case necks should still show soot. however, the necks will not need sizing ie bullet doesn't slip into neck. if there is no clearance between neck and chamber, you can run into some pretty scary pressures - kaboom. So please be careful.
Keep the chamber neck area clean and polish the necks of the fired cases with steel wool. Just about any dirt is going to take up the little clearance you have and pressures/accuracy will be bad.
Match chambers are wonderfully finicky creatures. Shoot safe...