neck tensions

[memilanuk]

Hello,

I'm fairly new to the 6mm BR, but so far liking what I'm seeing. My Savage 10FP w/ a SSS/Douglass barrel is humming away @ 500yds w/ the 'classic' 107gr SMK / Varget / CCI450 load.

What does worry me is that when I go to seat the bullets, whether w/ my Redding six-hole turret and Redding Competition seater, or w/ a stainless Wilson micrometer-topped hand die and a Hart arbor press... I can definitely feel a difference in seating the bullets from case to case. Not too many, and so far it hasn't shown up on target,furthest I've shot the gun is 500yds in a F-Class match... 18 out of 20 shots into a nice round group the size of the end of a soda can... the other two I shanked a little ) but it does worry me some nonetheless.

These cases have been trimmed w/ a Wilson case trimmer, deburred, vld chamfered, neck-turned for a light,50-70%) cleanup to ~0.0131" as near as I can measure w/ a Mitutuoyo ball mike from Russ Haydon. The neck turner was a K&M, from before the pilot jack attachment came out, w/ a fluted carbide mandrel...

Any ideas or suggestions?

TIA,

Monte

 

[Forum Boss]

Monte,

I found that, with a K&M VLD chamferer it was VERY difficult to get the exact same chamfer on each case. Go a tiny bit too far and it reduces the "grip" in the first part of the neck dramatically. I went back to a std Forster chamfer tool and results seemed to be better.

The other thing that can help is to get the necks very clean and maybe spin a little 0000 steel wool inside to polish.

On new Lapua brass I always run an expander mandrel in first. The necks are VERY tight out of the box and seating effort was too high if I didn't expand first.

Some guys like to lube the inside of the necks with a dry lube. That smooths bullet entry, but I wonder whether lube application can be done with sufficient consistency.

Last thing--try a little less neck tension.

 

[memilanuk]

Yep, I had to run the cases over an expander mandrel first as well... too tight to seat a bullet, much less turn necks. The cases are in two batches of 100... one fired 3X, the other 2X.

The chamber used is supposed to be I think a .272" neck; fired cases come out at .271", loaded rounds measure a hair under .270". I'm using a .268" bushing.

I'll try cleaning/polishing the insides of the necks. Would chucking up an old bore brush w/ a patch and some JB on it in a drill press be excessive?

TIA,

Monte

 

[Forum Boss]

I'll try cleaning/polishing the insides of the necks. Would chucking up an old bore brush w/ a patch and some JB on it in a drill press be excessive? --Monte

Monte, I wouldn't use power. I'd just put some 0000 steel wool on a nylon inside-neck brush and give it a few strokes.

 

[outlawsix]

I'm curious about the comment on the K&M VLD chamfer tool. I've just gotten one. I thought that with the built in depth feature it would be more uniform. Didn't the depth stop help with this?

 

[Forum Boss]

I'm curious about the comment on the K&M VLD chamfer tool. I've just gotten one. I thought that with the built in depth feature it would be more uniform. Didn't the depth stop help with this?

Even with the three fingers and taper the end of the cutter, they rock/wobble a little bit. Not saying you can't get good results, but you must be very careful not to over-chamfer or you'll thin out the very end of the neck and that will create significant differences in bullet seating effort.