338 Lapua Improved Reamer Help

[Catfur]

I'm going to build (i.e. a gunsmith I hire is going to build) a 338 Lapua Improved. I'd like a 35 deg shoulder, and I'm working with JGS on a reamer.

It's being built on a Kelbly Nanook action, and that takes a Wyatt's extended mag box for a COAL of 3.825".

I want to be able shoot 300gr Accubond LRs, A-tips, and Bergers. And I either need to figure out the right throat length or come up with a dummy(ies) seated to the right length.

Also, the basic print I'm starting from has a lead angle of 3deg 23", which seems steep to me. My 6XC reamer uses a 0deg 45' lead.

Any thoughts?

 

[Dusty Stevens]

What did your gunsmith recommend?

 

[DaveTooley]

1'30" is what I use on everything.
If you have bullets in hand you can figure the ogive length. Scribe a line with a pair of calipers set -001" under bullet diameter. Then measure the ogive length. Remember the transition from the neck to the freebore will add .015"-.020" to the freebore length. Make your freebore .339". You're burning a lot of charcoal and a little extra room doesn't hurt anything. Then allow some room for throat erosion. I did a 30 degree case several decades ago.