Thinking on a new rifle

[bruce moulds]

mustanggt,
the right 40 cal can mix it with a 45 at 1000 yds.
to do this the 40 needs at least a 400 gn bullet and a min of 80 gns of powder.
400 gn bullets will be suited to a 14" twist.
better still is a 440 to 460 gn bullet out of a 13" or even a 12" twist.
the 40/72 or 40/82 cases can deliver this with pp bullets seated 1/8" in the case, for a heavier bullet, and can handle 400 gn greasers similarly.
a better case might be the 40/85 ballard which can easily be formed from 9.3 x 74 brass.
the 40/70/2.5 will not have the capacity for a serious 1000 yd gun, as it is really only a 40/65.
it would be fun trying and learning with one however.
the 2 advantages of a 40 over a 45 are reduced recoil and reduced alloy cost.
ballistic coefficient of a 450 gn elliptical 40 cal is similar to the best 45 cal bullets available, so given the same muzzle velocity they will have the same trajectory and wind deflection.
I have been shooting a 40/72 using 405 brass for some years, and it has similar comeups to a 540 gn money bullet driven by 100 gns of powder from a 45.
I have been accused of being a gamer using this case, but Jamison now seems to do 40/72 headstamped.
whether csa will oblige special requirements with regards twist and chamber dimensions would need to be investigated.
ultimately it is good to have your own reamer, and another reamer to make a fls die for that chamber.
keep safe,
bruce.