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16" 7 Mag

gunner1stclass

gunner1stclass

Well-Known Member
Joined
Dec 29, 2021
Messages
52
Location
Kemmerer Wyoming
So this is a question for those of you that shoot short suppressed 7 mag. I have an old Remington 700 in 7 mag that I am thinking about cutting the barrel to 16 1/2 inches for use with a suppressor what can I hope for velocity wise out of this gun and any thoughts on the best powders to use would also be appreciated I will be running a Banish 30 can on it. Any thoughts and advice are appreciated before I go to the gunsmith. :) Also while I'm thinking of going down to 16 1/2 inches am I better off sticking with say 20 inches how much do I really lose per inch of barrel length? Thanks in advance I appreciate any help and advice.
 
I think you'll lose a lot more velocity cutting from 20 to 16, just based on the powders that the 7 typically uses. You could likely accommodate for a portion of that by switching up powders. Will you be loading for it?

This is a handy reference chart for 28" down to 20" to give you some real world numbers to work with.

Your banish 30 is rated for 16" minimum on a .300 win, so you are knocking on the door of the limit of the can if you go that low.

Personally I would go 20". By the 18" mark you basically have 7-08 velocities but at burning massive powder quantities to do it.
 
www.longrangehunting.com

6.5 prc / 300 prc / 7 prc barrel test

Testing results of cutting 26 inch barrels down to 18 inch barrels in 7 PRC, 300 PRC and 6.5 PRC I ran these numbers from station pressure on site Alabama 30 inches of mercury 275 feet above sea level and then hunting near Fort Smith Montana at 26.7 inches of mercury or 3200 feet above sea...
www.longrangehunting.com www.longrangehunting.com

Barbour creek cut all the prc's down to 18" and published the results
Looks like speed loss increased per inch the shorter it got. Would still kill everything that stepped in front of it

I use H4831SC in my 20" 7rm.
H1000 launches the 150's just as fast, but ES was worse.
N560 would have good speed Im guessing too, but that has poor temp stability. The right powder really depends on how heavy of bullet you want
 
Last edited:
I'd expect to drop 250-300 fps with a 16" barrel compared to a 24-26" barrel. Basically, you'd have the same performance as a 24" 7/08, but with a much shorter package. If that's a number you're happy with, chop the barrel and enjoy!

I've spent quite a bit of time around specialty pistols ranging from .223 sized cases up to Cheytac cases with barrels in the 16-20" range. Short barrel performance with the bigger cases will surprise a lot of people.
 
I assume your going to go with lighter bullets to mitigate velocity drop? At 16.5" while its handy with suppressor for me the diminishing returns on velocity, energy and powder consumption would prevent it. Maybe 18.5" but really even 19" would make it a handy rifle
 
Mike6158 said:
It should look cool when you shoot it at night.
Click to expand...
I run a 17" 28 Nosler in an an SP rear grip SA ,case full of retumbo,180 Bergers 2850ish ,Jp tanker brake,single digit ES and SD,very,very faint muzzle flash.I hunt mostly with pistols with rifle scopes when by myself, 16'-20" rifles if chasing yotes with trucks and dogs,23-26" barrels are unhandy in a blind and truck chasing yotes.25 creedmoor in an xp-100 is mine and my wifes favorite,same ballistics as 6.5cm with a 26" barrel
Faster powders in short barrels have greater muzzle flash than magnum powders.Poured out some old 4831 and old 4895 pulldown in 50' line,lit it,you can drink a beer casually before it burns out.
I have the bench /range in the area for forty years.Seen some crazy stuff.
 
Wouldn't go shorter than 20". Mags require longer bbls, otherwise, use a standard cartridge. Considering the gunsmithing work, pulling, cutting, recrowning and reinstallation, might just want to buy another bbl and consider a different cartridge. Used bbls in good condition can be found. Barrel replacement is pretty easy.
 
i went 18" with my 7wsm since that was the minimum with TBAC and magnums.
I don't know true loss of velocity since I rebarreled it due to the original barrel was too thin for the CB brake.
But, presumed loss was around 300fps. Breaking in the barrel with factory loads we're in the 2700's
Made my reloads with 155gr Hammers and my final load is getting me 3070fps.
Balance on the rifle with my Ultra7 isn't perfect, but still a great gun.
16.5 would probably balance better but that wasn't an option for me
 

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