hi,

i need to know at what length could you shorten a 7mm rem mag rifle barrel . it is a sako 75 and my friend wants to put on a end can and so not to be to long he would like to shorten the barrel.

thanks

If he doesn't care about losing velocity then he can take it to whatever length is acceptable in the UK. Here in the States you can only take a rifle barrel to 16 inches. The performance of a 7mm Magnum will suffer significantly below 22 inches.

hi,

is there a formula for length of barrel for ballistics or even a web site that shows it.

thanks

quote:

is there a formula for length of barrel for ballistics or even a web site that shows it

I've never seen a formula. Depends on the case to bore ratio, the powder and the starting point. Going from 28 to 26 will impact different than 24 to 22 etc.

If you know what he shoots. Bullet, load if he reloads I can run it through loadtech and give you a very rough guess.

thanks,

will find out and let you know.

My 26" 7mmRM shoots moly 175 gr Hornady #2850 at 2850 fps [part number same as the velocity] with 65 gr H8831SC and Per Quickload 2848 fps and 53kpsi



If I were to shorten the barrel:
26" 2850 fps 0 yards muzzle pressure 11,826 psi
25" 2818 fps 15 yards
24" 2788 fps 30 yards
23" 2756 fps 45 yards
22" 2722 fps 60 yards
21" 2685 fps 80 yards
20" 2646 fps 100 yards
19" 2605 fps 121 yards
18" 2560 fps 145 yards
17" 2512 fps 170 yards
16" 2459 fps 200 yards muzzle pressure 20,193 psi

Of course with a lighter round nose bullet, the velocity will slow down faster, and a short barrel length will not give up as many yards, but will still be the same change in noise at the muzzle.

hi ,

here is the load data what my friend is using.

140g head
62g imr4831
3020 fps.

and he is thinking of chopping the barrel to 20 inch.
if by cutting the barrel would it change its accuratcy.

regards
chris

quote:

here is the load data what my friend is using.

140g head
62g imr4831
3020 fps.

Loadtech says his velocity would drop to 2930fps. I assumed his barrel was the factory 24 3/8"

As to accuracy. Quite often a shorter barrel will be more accurate because it is stiffer.

In your buddies case. It is very unlikely that after he shortens his barrel and adds the can that his current load would still be his most accurate.

He is not really pushing the 7mag with his loads. He should be able to make up the velocity loss without much trouble. Plus going to a faster powder would also reduce the muzzle blast.