Muzzle brake calibre tolerance

[Tom Highway]

Apologies if this might seem a rather silly question, but I am a tad confused and need some clarification, if possible, as I don’t want to blow my rifle up!

I’ve never used a muzzle brake before, either shot with nothing attached to a barrel or with a moderator screwed on. On all the moderators I've had the tolerance of the bore was large and a bullet could be dropped in, and it would go through and drop out at the muzzle end.

So, I purchased a Waters rifleman mongrel hybrid brake "up to .30" to fit to my .308 Ruger precision. On fitting it, out of curiosity I tried to see if a 175gr SMK would be able to drop down into it, which it could not, it lodged in the muzzle, like if I was trying to push the bullet down the muzzle of the rifle barrel. I know bullets cannot drop through a rifle barrel and are designed to fill the bore completely so gas cannot escape around them when fired, so need a lot of force to go down the bore, but is the bore/muzzle of a brake designed to be the same, or should it have some "free play" like my moderators??

I tried to speak to Waters rifleman via e mail (they are Australian) thinking they could confirm or deny what should happen, not much help TBH just said I should refer to where I purchased in the UK... Has anyone got one of these and can confirm the bore tolerance? should brakes be like this? Just want to check before I pull the trigger and my barrel goes boom !! thanks

 

[Andy RV]

The bullet should definitely pass freely through the bore of the muzzle brake!

Can you measure the diameter of the bore?

 

[Tom Highway]

The bullet should definitely pass freely through the bore of the muzzle brake!

Can you measure the diameter of the bore?

i can try with my calipers

 

[Klenchblaize]

Bullet diameter	0.308 in (7.82 mm)
Land diameter	0.300 in (7.62 mm)

 

[Tom Highway]

So i am getting around 0.271 (5) with my calipers, so i think a little under ???

 

[VSS]

If a bullet won't drop freely through it, don't use it for that calibre.

 

[Andy RV]

Looks like a 6.5mm brake, send it back and consider yourself very wise for checking!

 

[Tazz]

I had a thread running on muzzle brakes for 300wm. I bought a Vais that says on the packaging the same as yours .30 calibre my 300wm slightly smaller than your .308 but I also measured mine and it is “ clearance” for a .30 calibre about .5mm and it performed well when I shot it for the first time. Sounds like your .3 is the actual siz rather than clearance for that calibre

 

[Ronin]

So i am getting around 0.271 (5) with my calipers, so i think a little under ???View attachment 345628

Don’t use it if you are shooting .308

You need at least .020” all round tolerance - possibly greater dependant on who threaded the muzzle / brake

Always useful to use a range rod when fitting brakes to get minimal clearance but know it exists

 

[Tom Highway]

Don’t use it if you are shooting .308

You need at least .020” all round tolerance - possibly greater dependant on who threaded the muzzle / brake

Always useful to use a range rod when fitting brakes to get minimal clearance but know it exists

Range rods seem to be quite precise bits of kit, where can you source one ?

 

[jthyttin]

Range rods seem to be quite precise bits of kit, where can you source one ?

From the reamer maker that most of your live pilot reamers are from. They usually use same bushings, so you save on that.

 

[Klenchblaize]

Looks like the Op has had a close shave but full marks for checking exit tunnel.

K

 

[Zio65]

Personally I wouldn't try to use it, in fact I consider it extremely dangerous

 

[Outback]

I would mic a bullet and add the tolerance required and get a machine shop to bore it out to the required size , if it screws on the barrel etc .

 

[Lateral]

My brakes run 1mm /40thou over the bullet diameter, and as Ronin mentioned, concentricity on the barrel thread can be an issue.

The bullet should drop through the brake very easily.

 

[Tom Highway]

Update, having rung riflemags today, they have already sent a replacement out, it would appear that Waters rifleman in Australia had already contacted them after our "terse" e mail conversation last night. Needles to say i will be checking this one when it arrives ! Points to note I'm not sure who bags the brakes up, in Australia or UK, but who ever seriously needs to look at their quality control as putting the wrong calibre brake in a bag marked with another calibre is a very serious and dangerous practise !! Secondly these brakes appear not to have any calibre stamped on them, so perhaps Waters rifleman needs to consider stamping size on their brakes which may make bagging them up a whole lot easier ........

 

[Tom Highway]

I would mic a bullet and add the tolerance required and get a machine shop to bore it out to the required size , if it screws on the barrel etc .

I could, but why should I ? its not my fault its wrong and i would not pay to have it bored out, i appreciate your comment and option to fix, but am not going to spend money on fixing a F***K up which is not my fault LOL

 

[shortshot]

wang a drill through it till bullet drops through would be easiest quickest solution. Perhaps I’m more impatient with new toys than most?

 

[Claret_Dabbler]

Does a muzzle brake require proofing?

 

[Andy RV]

Depends if you’ve got money to waste….