.308 Freebore

[Dgd6mm]

I had a Criterion barrel from Jim Briggs chambered in .308 1-11 twist, freebore from them comes standard at 0.90. This thing shoots 175 and 178 bullets verygood. I would like to shoot the 185 Berger LRBT for 1000 yards and down to a 155 class bullet for 600 yards. What freebore can I get away with, if possible, and not be over jumping the 155's and still get the 185 out far enough to get the speed for 1000yards?

Thanks,
Don Dunlap

 

[LESLEY]

PM sent

 

[Dgd6mm]

Thanks Lesley.

 

[TimP]

I had a Criterion barrel from Jim Briggs chambered in .308 1-11 twist, freebore from them comes standard at 0.90. This thing shoots 175 and 178 bullets verygood. I would like to shoot the 185 Berger LRBT for 1000 yards and down to a 155 class bullet for 600 yards. What freebore can I get away with, if possible, and not be over jumping the 155's and still get the 185 out far enough to get the speed for 1000yards?

Thanks,
Don Dunlap

I am in the process of building a .308 myself and would be interested in the recommended freebore for the same bullet weights. I plan on running 155gn scenar's and Sierra 168 & 175 gn MK's.

 

[LESLEY]

anoother PM sent

 

[19zip]

I'm also in the process of building a .308 and would be interested in the recommended freebore for the same bullet weights. I plan on running 155s, not sure which ones yet, SMKs, Noslers, maybe Berger HBs and the Berger 185 LRBTs also. Thanks for any help or recommendations .

 

[LESLEY]

PM number 3 sent

 

[LESLEY]

If you want a 308 F/TR built call dave bruno 814-257-8089. You wont find another 308 builder with more rifles that hold National records

 

[ThunderDownUnder]

There is no mystery about throating a chamber for the 308W to suit a number of different projectiles but it does require some importantant facts. What brass will be used for the loads and of course the size of the powder charge. If you are wanting to compete in F T/R then you want a pretty full powder charge to launch the 155-185gr projectiles, I use a throat length of 110 thou (0.110"). This enables me to use full powder loads of Varget in Lapua Palma brass and launch the 155gr bullets at 3000+fps and the 185gr LRBTs or Hybrids at 2830+fps. I have found a throat of 100 to 120 thou about the right size as I always like to have at least 120-150 thou minimum bullet bearing surface in the neck for 308W.

A rough guide is to look up the max powder charge in the powder manufacturers handbook and to place it into the case you will be using. Seat the bullets you have selected on top of the charge, without compressing the load and measure the OAL. Use the OAL of the loaded (no primer) round as a guide for the length of throat you are going to need. If you know the length of the throat in your current 308W chamber and the OAL of rounds with the same projectiles being used then you know approx how much deeper the throat needs to be to accomodate the OAL of your test rounds. You need to allow for where you think the bullets will be seated as in jammed or jumped but you get the idea, make up test rounds to measure and work from that if you cant get the info direct from someone who has already established a starting point.

Ian

 

[gsg5pk]

I had called Dave Kiff, without neck turn he recommend .343 nk with .088 fb with 1°-30 .

So, this chamber will proper for these bullets?

.30 Sierra 175 SMK (Practice)
.30 Berger 175 LRBT
.30 Berger 185 LRBT

 

[Dgd6mm]

Thanks for all the replies.