Cutting Barrel Down on 300BLK MCX

[MMH]

I have a Sig MCX in 300 Blackout w/ a 16" barrel. The rifle shoots very well for what it is. Consistently 2 moa or better. Not talking about the best 3 round group shot ever but consistently shooting 2 moa based on five groups of five shots. Anything from subs to 125 gr. supers.

Anyway, I want to cut the barrel down and permanently attach a suppressor so that I have a suppressed rifle w/ an approximate 18" barrel/suppressor length. To get to this means that the barrel itself is cut down to 10.5". I am concerned about the accuracy going out the window. After cutting the barrel, I would recrown w/ a quality barrel crowning tool. I would not be too upset if the accuracy decreased a little but just would not want to turn a 2 moa rifle into a 5 moa rifle.

Can those w/ a 'pistol' or SBR MCX comment on accuracy?

 

[Hecouldgoalltheway]

I have a Sig MCX in 300 Blackout w/ a 16" barrel. The rifle shoots very well for what it is. Consistently 2 moa or better. Not talking about the best 3 round group shot ever but consistently shooting 2 moa based on five groups of five shots. Anything from subs to 125 gr. supers.

Anyway, I want to cut the barrel down and permanently attach a suppressor so that I have a suppressed rifle w/ an approximate 18" barrel/suppressor length. To get to this means that the barrel itself is cut down to 10.5". I am concerned about the accuracy going out the window. After cutting the barrel, I would recrown w/ a quality barrel crowning tool. I would not be too upset if the accuracy decreased a little but just would not want to turn a 2 moa rifle into a 5 moa rifle.

Can those w/ a 'pistol' or SBR MCX comment on accuracy?

If done correctly, you shouldn't lose any accuracy. My Smith has chopped a dozen rifles for me, (once you get suppressors, everything is too long right?), and none of them ever suffered from any loss of accuracy.

 

[91Eunozs]

300BLK’s useable performance envelope is well within what can be achieved with a 10.5” barrel; especially for subs.

 

[the monk]

Why 18"? Why not just do 16.1"?

 

[MMH]

Why 18"? Why not just do 16.1"?

My suppressor is 7.5" long. A 10.5" barrel results in 18" barrel/suppressor length (I'll help you: 10.5"+7.5" = 18"). Don't want to get below 10.5" because I'll be giving up too much supersonic performance. 16.1" results in a barrel length of 8.6" which for me is too short of a barrel.

They need to start teaching remedial math in monk skool.

 

[the monk]

Wow, you're super friendly. Just buy the 9" barrel from Sig and keep the 16". 9 + 7.5 =16.5. Who TF wants an 18" 300 blackout? I have had no issues killing lots of things with 9" 300blk.

 

[MMH]

Wow, you're super friendly. Just buy the 9" barrel from Sig and keep the 16". 9 + 7.5 =16.5. Who TF wants an 18" 300 blackout? I have had no issues killing lots of things with 9" 300blk.

Sorry.

Thought you were just being a smart a** putting in an arbitrary number like 16.1". Again, don't want to sacrifice too much supersonic performance. Also, the sig barrel is not cheap (approx. $800). After I chop down, will have no use for my 16" barrel.

 

[Magsz18]

Sorry.

Thought you were just being a smart a** putting in an arbitrary number like 16.1". Again, don't want to sacrifice too much supersonic performance. Also, the sig barrel is not cheap (approx. $800). After I chop down, will have no use for my 16" barrel.

That's not an arbitrary number my good man. Since you're pinning the can you already know about legal length for rifle barrels etc.

May I ask why you made the comment about sacrificing supersonic performance? I hunt hog with a 5.5 inch 300 blackout Rattler without any issues. Granted, I always try and get within 75 yards for my shots.

What game are you taking and at what distances? I'm always curious to see how people are employing their 300 blackout rifles!

 

[MMH]

That's not an arbitrary number my good man. Since you're pinning the can you already know about legal length for rifle barrels etc.

May I ask why you made the comment about sacrificing supersonic performance? I hunt hog with a 5.5 inch 300 blackout Rattler without any issues. Granted, I always try and get within 75 yards for my shots.

What game are you taking and at what distances? I'm always curious to see how people are employing their 300 blackout rifles!

Not hunting at all. But do want ability to hit accurately to 300 or 400 yards. Not worried about the drop, but low velocity & low BC make doping the wind VERY challenging, so I want to keep the velocity up.

With 125 gr. bullets I am getting 2250 FPS out of my 16" barrel. I am guessing that the powder is fully burned up well before it gets to the end of a 16" barrel & going down to 12" will have a negligent impact on velocity. After all, a 300 BLK uses magnum pistol powders (H110 works well for me) which still burns fast compared to rifle powders. Just a wild guess, but going down to 10.5" will still result in a velocity of 2150 FPS. I am afraid that at that point the velocity starts dropping quick.