308 muzzle brake ?

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crazyelece
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308 muzzle brake ?

Post by crazyelece » Sat Apr 02, 2016 12:29 am

Is .335+.005 too tight for the through bore for a 308 win muzzle brake?

I'm going to bore my baffles and end cap to .360+.005

My can is going on a FN SPR and it will be thread on 5/8x24

The barrel side end cap is going to have a built in muzzle brake to help with erosion, but being a bolt gun it's not going to see a lot of abuse

Rich V
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Re: 308 muzzle brake ?

Post by Rich V » Sat Apr 02, 2016 6:39 am

I use 0.350 for my 30 cal muzzle brakes. For baffles I use 0.365 - 0.375 progressively increased from the muzzle.

smustian
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Re: 308 muzzle brake ?

Post by smustian » Sat Apr 02, 2016 9:32 am

>335 sounds mighty close. Better make sure that the bore is perfectly concentric with the threads and can when installed. Most people use .375 for the baffle holes. Some go as high as .390.

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gunny50
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Re: 308 muzzle brake ?

Post by gunny50 » Sat Apr 02, 2016 10:03 am

I use 8 or 8.15mm all depending if it is for civilian or L&E / military use.

CNC in one operation, so things are in line.
This also differs if its a FH or MB. and length of course, but til today with 1000's of rounds never had a problem.

Gunny
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300sniper
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Re: 308 muzzle brake ?

Post by 300sniper » Sat Apr 02, 2016 3:41 pm

If you are having clearance problems 1.5" from the muzzle with a brake .030" over the bullet diameter, you have other serious issues that need to be corrected.
It's time to switch to whiskey, we've been drinkin' beer all night.

crazyelece
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Re: 308 muzzle brake ?

Post by crazyelece » Sat Apr 02, 2016 6:03 pm

It's concentric within the tolerances of my equipment and testing/measuring devices.

If I had to put a number on it within .005 probably closer but I don't have the equipment to test.

I am confident the pill will clear the hole without any chance of physical contact, I just wasn't sure if I needed to open it up some more to keep the gasses from disrupting flight or destabilizing it

If it matters, the plane of the brake is about 0.5" in front of the bore.

The rifle has about 0.75" of threads so the distance could be increased some if it would make an improvement.

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LavaRed
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Re: 308 muzzle brake ?

Post by LavaRed » Sun Apr 03, 2016 2:53 pm

I've just completed a 30 caliber can with 0.35" bore at the baffles. This is the minimum I'd dare go.
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Samson1044
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Re: 308 muzzle brake ?

Post by Samson1044 » Mon Apr 04, 2016 6:53 am

Depending on how you can set it up will decide how tight you can go , I'd dialed barrels in off the ID of the bore and bored the brake to only .020" over bullet diameter and progressively reamed it at the range to see if the tighter bore showed any benefit in recoil reduction (it didn't).

Id suggest threading the 5/8x24 mount then cutting a 5/8x24 male stub in the lathe , screw the brake on the stub and bore the exit hole to desired ID , .350" is fine and will allow some room for error should you put the can on a barrel who's threads aren't perfect.

crazyelece
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Re: 308 muzzle brake ?

Post by crazyelece » Mon Apr 04, 2016 1:53 pm

Samson1044 wrote:Depending on how you can set it up will decide how tight you can go , I'd dialed barrels in off the ID of the bore and bored the brake to only .020" over bullet diameter and progressively reamed it at the range to see if the tighter bore showed any benefit in recoil reduction (it didn't).

Id suggest threading the 5/8x24 mount then cutting a 5/8x24 male stub in the lathe , screw the brake on the stub and bore the exit hole to desired ID , .350" is fine and will allow some room for error should you put the can on a barrel who's threads aren't perfect.
Pretty much exactly how I did it. I turned it out of 2" bar stock. Turned down to 1.75 to match the tube.

Turned down and threaded to mate to interior threads on the tube.

Then further turned down to .825 for the brake section and opened up through bore to .335

Next switched sides and adjusted in 4jaw to center. bored and threaded 5/8x24.

Threaded on rifle and marked horizon line for porting (not sure horizontal porting is necessary within the can but it looks good).

Still has to go into the mill to finish the porting and lightening (a lot of material left between the threads for the tube and the brake)

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