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barrel diameters and muzzle brakes.

 
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  #15  
Old 05-14-2014, 07:24 PM
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Re: barrel diameters and muzzle brakes.

It seems there are some standard muzzle threads, but I got a barrel that is odd.... 1/2 -24.

It was read to install but got surplused and I got it for $100. I am putting in on a Mosin Nagant.

I had to make my own thread protector from some hex steel.
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  #16  
Old 05-14-2014, 10:27 PM
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Re: barrel diameters and muzzle brakes.

I've been concerned about min thread diameters especially with factory RUM's which seems to be the most popular to brake if you can imagine that.

I talking it over with an engineer who is familiar with what I'm doing and he put together a program for me to just punch in numbers and it tells me where I'm at and gives me a safety factor for that specific case since it changes with bore diameter. He built in some safety by using the numbers for 416 Stainless in an annealed state.
I punched in the a .310 bore with .648 OD and my program tells me it's good to 18,000 psi muzzle pressure with annealed 416, a bare 9/16-28 thread is right at the line with annealed 416, I forget the term he used but that line is just where the metal will start to move but it will spring back and not permanently deform or fail for quite a little more pressure so a 9/16-28 is well within spec and 1/2-28 is good for 13,000 psi on annealed 416. A 4140 barrel steel is good for quite a little more and a 1/2-28 is well within it's operating range on the .310 bore.
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  #17  
Old 05-15-2014, 07:58 PM
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Re: barrel diameters and muzzle brakes.

How can you calculate the pressure of a 375 RUM at the muzzle,
with 26-in barrel ?
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  #18  
Old 05-15-2014, 09:25 PM
Edd Edd is online now
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Re: barrel diameters and muzzle brakes.

Quote:
Originally Posted by hemiford View Post
How can you calculate the pressure of a 375 RUM at the muzzle,
with 26-in barrel ?
You can't, but you can drill a hole in the barrel and measure it with a transducer.
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  #19  
Old 05-15-2014, 09:46 PM
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Re: barrel diameters and muzzle brakes.

Quickload will get you close or I get exit pressure data from a pressure trace system if it is something I can put a sensor on.
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  #20  
Old 05-15-2014, 10:38 PM
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Re: barrel diameters and muzzle brakes.

Hmmm.
I can't do any measuring. But, with a little reasoning I can predict the
muzzle pressure on the 375 would be less than a 300 RUM because
it has a greater expansion ratio (same barrel length). Offsetting that fact,
however, is that the 375 has a thinner wall thickness at the muzzle,
(both are factory barrels).
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  #21  
Old 05-15-2014, 10:48 PM
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Re: barrel diameters and muzzle brakes.

I have quickload that calculates muzzle pressure.
I can calculate thin wall and thick wall hoop stress in steel.
All this talk about threaded muzzles failing is silly.
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