7SAUM Freebore

LR Guru

Formerly '300NM_guru'
Joined
Jan 24, 2020
Messages
102
Location
Washington
yes its another freebore thread I'm just going to make this short and simple. I'm building a 20" CF 7saum on a long action the reamer the smith has on hand has a freebore of .158. I mostly planned on shooting 168 class bullets (hybrids or ELDm), with the possibility of shooting 180s. should i stick with the .158 freebore or extend it?
 
I'm running a .195 freebore for 180 hybrids.

This is one set .020 off the lands which gives a COAL of 3.1". The bullet is placed perfectly at the neck shoulder junction.

Screenshot_20230315_054719_Gallery.jpg
 
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So the 7 Saum has a 30 degree angle and it shows good accuracy with the .195 freebore for the 175/180 grain bullets. Now looking at the 30 degree angle 7 prc with .233 freebore. What is to much for a .284 caliber bullet? Just wanting to be as learned as I can since I have a 3b sitting in my safe waiting to be born. Correct or enlighten me, please.
 
I can't answer that but it's highly dependent on what type of bullet you intend to shoot.

A heavy for caliber vld such as the 180 berger will protude deep into the case robbing you of powder capacity.

Same for many of the copper solids, they're long for their weight and greatly benifit from the freebore.
 
I would want .220-.230 freebore so you get your bullet above the neck/shoulder junction and leave yourself room to jump the bullet without being below the neck/shoulder junction. You have the room, so I wouldn't want to have a short freebore in a long action.
 
Good thread. I'm getting ready to build one on a LA anTi with a 22" Bartlein #3, primarily to shoot 175 EH's.. I haven't found a smith with a 0.195 or more freebore reamer yet that will do a prefit. I'm trying Alamo Precision tomorrow, thanks Slick8.
 
Good thread. I'm getting ready to build one on a LA anTi with a 22" Bartlein #3, primarily to shoot 175 EH's.. I haven't found a smith with a 0.195 or more freebore reamer yet that will do a prefit. I'm trying Alamo Precision tomorrow, thanks Slick8.
Let us know if Alamo will chamber one for you. I for one would like to know. I asked Hill Country a while back and didn't chamber for prefits. I haven't checked back to see if their policy have changed.
 
Lots of guys will do them. Alex is moving. I would have Dallas Lane or Mike Manzella do the chambers. Both would do a great job. Mike does cerekote in house which is nice.
 
Lots of guys will do them. Alex is moving. I would have Dallas Lane or Mike Manzella do the chambers. Both would do a great job. Mike does cerekote in house which is nice.
Thanks for the info, I was asking since it was stated that a member was going to contact Alamo which is less than 30 miles from me. I can also call. My concern is going with someone who hasn't done a prefit compared to someone that has done many. The last barrel I had chambered I had to send a go gauge along with the reamer to spec from.
 
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