what should .223 freebore using berger 70gr vld

[swamprat1]

I'm building a tube gun .223 Rem. 1 in 8 twist 27" barrel. I will be shooting Berger 70gr vld & 75 gr vld
mostly shooting 300-600 yards. I need to know what the free bore should, I'll be loading .010-.015 off lans.
I don't want to get to long and have concentricity problems, and not to short to have pressure problems.
Thanks for the help
swamprat1

 

[FroggyOne2]

I believe that if you use the same as on the Wylde chamber, you should be good to go.

 

[swamprat1]

Does anyone else have comments on the free bore length. I shoot F T/R
Thanks
swamprat

 

[jhelmuth]

Take it for what it's worth... (long way away from an expert)

I take the desired bullet and load it into a newly FL sized cartridge (which I do every loading as I have my dies setup to my chamber) one caliber in depth. On my .223, that seems to be the perfect depth for what I shoot. I then take a measurement for the ogive (as this is where I want to base my throating) and then have the throat reemed for that length. Now I can vary the seating a bit to touch the lands, have a slight jump, or possibly jammed just a bit (which - so far I do not do). I do not actually throat my barrels... I let my smith do that. I always give him a smaple bullet and the dummy loaded cartridge to use.

Recent example was .223 chambered CBI barrel with 1:8 twist shooting 75gr AMax (and I can shoot the 80gr SMK as well with a slight adjustment). the COAL was 2.467 and the ogive length was 1.941. Bullet length was 1.106 measured and 0.579 to the ogive (and the BT base was .175), calc. bearing length = 0.707. So with a 1.760 cart. length, that would make the freebore ~ 1.941 - 1.760 = 0.186 (again... approx as I do not have exact measurements)

Maybe you could modify that if you knew the measurement on the VLD yoou wnat to shoot?

 

[swamprat1]

Thanks for the info. I had all the measurements. I was trying to make more of the calculations then what they are.