Breech seating a 50-70 or 50-90?

[andym79]

Hi guys I am looking to have a 50 caliber rifle built and am trying to decided between a 50-70 and 50-90.

I want to shoot heavy bullets, mostly for their higher BC. At the moment I am considering a design that will weigh in around 645 grains! The rifle will be heavy around #18, with a 28" barrel.

I never like to take these things by gospel, and value real experience above all theory; but from running Quickload to achieve by desired velocity of between 1300-1450 fps to keep pressure below 20kpsi I need to breech seat with the 50-70.

Whereas with the 50-90 I may be able to reach 1400-1500 fps using fixed ammo and possibly 1600fps with breech seating.

I am not saying that I have to drive them at 1500 fps, but asking if the 50-70 can satisfactorily drive a 645 grain bullet and do well at 300-500 yards or is a 50-90 needed?

I might add that I can only get a 20 twist, which is faster than ideal, but getting a 50 caliber barrel exported is hard out of America and the slowest in Australia I can get is 1:20:though I think 1:26 would be better.

I know that the 50-90 is more versatile, and I may be able to loan a reamer, but the brass is so much less available and so much more expensive than 50-70.

In short I am asking for advise on if the 50-70 is enough case for a large bullet.

Thanks

[MT Chambers]

I would go for the 50/90 and load down if it's too much, oh and forget about the breach seating, it's more for target work and the 50/90 is a bit big for target shooting, but does make an excellent hunting gun.

[OlDeuce]

I would go for the 50/90 and load down if it's too much, oh and forget about the breach seating, it's more for target work and the 50/90 is a bit big for target shooting, but does make an excellent hunting gun.

Your right on !!!!

Ol Deuce

[tdoyka]

are you using black powder loads?
are you target shooting?

if yes, then i'd go with the 50-90.

if your going for deer type animals, then a 50-70 is a good choice. i wanted a 50-70gov but MGM doesn't make it. ( https://matchgrademachine.com/ ) so i chose the 500 linebaugh(tc encore in a 23" MGM barrel) instead. i believe it is a 1 in 20" twist(or a 1 in 28" twist, i forget). i use a 450gr lfn gc boolit( https://www.montanabulletworks.com/ ) but i believe it can go to 530?gr.

i think (i do that alot:confused::roll:) that the 50-70gov used a 425?gr fn.