Tuning a Muzzlebrake

[winmag]

Man there are some boring threads lately. I put some theory to the test the other day and while the results were predictable, they were interesting and yielded a cool photo.

I found a Christensen Arms MPR in 338 Lapua for a price I couldn't pass up. The rifle comes with their side baffle muzzlebrake which has 4 closable ports on top, closeable by set screw. The theory is that you can tune the muzzle rise by opening/closing the ports on top of the brake. I had to break in the barrel anyway so I thought I'd set up a slow motion video camera to see how many ports I needed to open to get the rifle to recoil straight back, not up. My iphone will do 240fps video, which is just fast enough to tell me what I wanted to know.

I loaded some 300gr Bergers at a starting charge weight, packed up my gun cleaning supplies, and headed to the range.

All ports closed: first frame of recoil, the first movement of the muzzle was up.
1 port open: same as all closed
2 ports open: same as all closed
3 ports open: first frame of recoil, the first movement is straight back
All ports open: first frame of recoil, the first movement is down

I could tell a slight difference in recoil when the muzzle was going straight back vs up or down, although it was still a little too much recoil to stay on target while shooting free recoil. I will also say that this muzzlebrake is very efficient. 300gr Berger doing 2750fps with a rifle weight of 9 pounds scoped and I would compare the recoil to a 280 Rem.

Interestingly, I managed to get a photo of one of the projectiles about 5" in front of the muzzle.

 

[std7mag]

Does it make any difference on which port is open, and which is closed?
Aka, rear 1 open, or middle 2 open, etc...

 

[winmag]

Does it make any difference on which port is open, and which is closed?
Aka, rear 1 open, or middle 2 open, etc...

Didn't test that. I started opening the ports from the front to the back.

 

[std7mag]

Just curious...

 

[winmag]

I suspect the closer to the breech, the higher the effect on muzzle rise.

 

[p_ham]

Does it make any difference on which port is open, and which is closed?
Aka, rear 1 open, or middle 2 open, etc...

Probably not enough to matter. The 2 closest to the muzzle will have the greatest change though.

A friend has a brake on his 6.5PRC that has 2 rows up top. You can tune which direction you want the recoil to bias. Pretty neat. I think it's called "Little Bastard"

 

[OntarioHunter]

An interesting concept. Did you notice any differences in muzzle blast?

 

[winmag]

I couldn’t perceive any difference in muzzle blast. All horrendously loud and violent, definitely needed plugs + muffs on the covered range.

 

[D_Walt]

Pretty cool pics. I have the same brake on a Christensen Classic in 30 Nosler shooting 215 bergers at 3020 FPS. I mostly shoot it prone off a bipod, All 4 ports opened up significantly reduced muzzle jump, though as I recall I couldn’t tell a lot of difference between 3 and 4 open.

 

[Siberian2025]

Man there are some boring threads lately. I put some theory to the test the other day and while the results were predictable, they were interesting and yielded a cool photo.

I found a Christensen Arms MPR in 338 Lapua for a price I couldn't pass up. The rifle comes with their side baffle muzzlebrake which has 4 closable ports on top, closeable by set screw. The theory is that you can tune the muzzle rise by opening/closing the ports on top of the brake. I had to break in the barrel anyway so I thought I'd set up a slow motion video camera to see how many ports I needed to open to get the rifle to recoil straight back, not up. My iphone will do 240fps video, which is just fast enough to tell me what I wanted to know.

I loaded some 300gr Bergers at a starting charge weight, packed up my gun cleaning supplies, and headed to the range.

All ports closed: first frame of recoil, the first movement of the muzzle was up.
1 port open: same as all closed
2 ports open: same as all closed
3 ports open: first frame of recoil, the first movement is straight back
All ports open: first frame of recoil, the first movement is down

I could tell a slight difference in recoil when the muzzle was going straight back vs up or down, although it was still a little too much recoil to stay on target while shooting free recoil. I will also say that this muzzlebrake is very efficient. 300gr Berger doing 2750fps with a rifle weight of 9 pounds scoped and I would compare the recoil to a 280 Rem.

Interestingly, I managed to get a photo of one of the projectiles about 5" in front of the muzzle.

My apologies for reviving a 4 year old post but when removing these screws out of the break did the accuracy improve? I recently bought a CA 338 MPR and I cannot get this thing to shoot anything less than a 6” group at 100yds and the rounds are all over the target. Myself, my brother and my nephew, all avid and experienced shooters cannot get this thing dialed in.