how to measure the throat that you want

[brian923]

i am going to be chambering a barrel for the 7 mm saum. i was wanting to know how you would pick the desired throat. how do i measure this? and what seems to work the best. i have a 1 in 8 twist so i will probably be shooting heavier bullets. thanks, Brian

 

[DesertLefty]

Having just gone through that process and been disappointed with the outcome,bullets are seated out further than I wanted), I'd say:

Make up some dummy rounds loaded with the bullet you want at the seating depth,or OAL) that you want and send them your reamer maker,Dave Kiff or whoever). Then let them advise you on throat length.

That's my 2 cents worth,

Lefty.

 

[rcw3]

i am going to be chambering a barrel for the 7 mm saum. i was wanting to know how you would pick the desired throat. how do i measure this? and what seems to work the best. i have a 1 in 8 twist so i will probably be shooting heavier bullets. thanks, Brian

Brian

If you are shooting the 175 Sierra and your chamber will have a one and a half degree throat angle and you want to keep the junction of the boat tail and bearing surface just forward of the junction of the neck and shoulder of the case, you need a minimum of about a .170" free bore. If you are going to shoot the Berger 180 VLD's, you need about a 225" free bore. I shot 7mm SAUM and have had three different barrels chambered in it and have two different reamers.

Robert Whitley

If possible I would go with a 1:8.5" twist, since an 8" twist is a little bit too tight. I have been shooting 1:9" twist barrels.