How to build a custom rifle

[Varoum]

I am in the process to build a custom rifle caliber .243/6mm for the very long range with 115gr and 105gr bullets. Twist rate is 7.5 barrel 30in.

I need help. My first question is: What bore diameter I need? The barrel maker is listing two .236 and .237.

Barrel maker is this one. http://bartleinbarrels.com/calibers.htm

 

[kombayotch]

If you want to shoot the 115/117s fast (>3100 fps), go with 0.237/0.243 and get 5R rifling. This will lower the chances of the bullets blowing up in flight. All of my 6mm Crusader barrels are Bartleins of this specification and they all shoot great. You'll only need the 1-7.5" twist if you're going with a .243 Win sized case or smaller. 6mmAI, 6mm Crusader and 6-284 will do just find with a 1-8" twist or a 1-9" to 1-8" gain twist.

 

[Varoum]

Thanks!

It will be a .243AI in 5R 7.5 twist .237 bore diameter 30in Bartlein barrel.

Next question: I will buy a reamer in .243AI what specifications I need?