Free Bore

[TF160 Guy]

I’m having an F-TR rifle built by a reputable smith with the following components.

Receiver. BAT VR with a .308 bolt face.

Krieger Heavy Palma 30 inch barrel with a 1:10 twist, 5R, Obermyer chamber.

I plan on using Lapua brass, CCI LR primers, H4895 or Varget with Berger 200.20X bullets.

Chamber length 2.0150”

I’d like to be able to jump at most 0.100”

What should the free bore be for this bullet-throat and leade?

Thanks

 

[Twitchy]

I'm not a smith or an expert on these things, but wouldn't it be easier/easiest to just make a few dummy rounds in the desired length, including the jump, for your smith to use when chambering?

 

[TF160 Guy]

I'm not a smith or an expert on these things, but wouldn't it be easier/easiest to just make a few dummy rounds in the desired length, including the jump, for your smith to use when chambering?

I considered this, but thought there might be a mathematical solution. As with all things in life there are two possible solutions.

Thanks

 

[Twitchy]

No doubt there is a mathematical solution. I think the problem then stems from how to consistently measure the base to ogive so that your smith gets the exact same measurement you arrived at with whatever tools he is using.

I am having a barrel made for one specific bullet and the smith/manufacturer preferred to have a few dummy rounds rather than go off of a number.

Either way I revert back to "I'm not an expert".


NSDQ