Bore diameter changes when turning down muzzle end?
- Thread starter js2013
- Start date
Dusty Stevens
Shiner
No on your second question
15 years ago I might have threaded 3, 4 muzzles a month. Now, I might NOT turn muzzles down for threads that many times a month. We are a 5-10 barrel a day shop.
If this was the issue magazine writers try to make it out to be, I'd of had my ass chewed over it by now ##### times. There's still plenty of it attached.
Never forget: Magazine writers exist to sell magazines.
If this was the issue magazine writers try to make it out to be, I'd of had my ass chewed over it by now ##### times. There's still plenty of it attached.
Never forget: Magazine writers exist to sell magazines.
LA50SHOOTER
Sworn To Protect The Constitution.
Based on what Gordy Gritters stated to me back 10+ years ago, Depending on how much the barrel is turned down at the muzzle end, say to thread for a brake, then there "could be some growth" of actual bore diameter. - "Some" being in the Ten-Thousands range.
- I then asked "How would / could" this effect accuracy ?" and he replied that it is not "a determinable thing" as it may have little to no effect or could in fact have a larger effect. Depending on how much reduction in actual barrel diameter was accomplished.
- Point is, muzzle brakes are used in many disciplines of accuracy shooting including some very precision & accuracy demanding disciplines such as 600, 1000 yard Benchrest, ELR & E2K competitions and the guns being shot with brakes produce very top level accuracy.
- My personal thoughts on brakes are. - IF I need one, it needs to be properly installed by a skilled machinist who knows how to correctly accomplish the task & as well, is aware that reducing the diameter beyond a certain point could in fact lead to potential "growth" which could lead to possible accuracy issues. - I am not a "fan" of muzzle brakes and if I can have the rifle built without one and maintain proper "gun handling" then I usually opt to not have a brake. - On a 50 BMG Improved it is not really a viable option for a competition rifle to Not have a good brake. So I try to chose a brake that the threaded portion of the brake that screws onto my muzzle doesn't reduce barrel diameter a whole lot. It makes me feel a whole lot better about having the brake installed on the rifle and not thinking about if, or how much the bore "grew" when I made the decision to have a brake installed.
My .02 - Ron -
The button rifling process introduces stress, cutting the muzzle for a brake might let some of that stress open up the bore but as mentioned, only by a tiny amount.
A cut rifled barrel will have minimal stress so if it moves, it is probably a lot less.
Neither is something to worry too much about.
A cut rifled barrel will have minimal stress so if it moves, it is probably a lot less.
Neither is something to worry too much about.
Imho, the question isn't if the bore grows, but does it really matter..I'm talking centerfire.
From my understanding, don’t they have to relieve the stress in the blank after the button rifling process? I suppose if they didn’t relieve it correctly it might open up if you turned down the muzzle for threading.
But then again, has this been reported much as a problem? It may be “realistically” not happening to an accuracy on paper measurable issue. Perhaps due to the quality of barrels today from our most reliable suppliers of button rifling match grade barrels.
I run single point cut barrels anyways so not too worried about it.
But then again, has this been reported much as a problem? It may be “realistically” not happening to an accuracy on paper measurable issue. Perhaps due to the quality of barrels today from our most reliable suppliers of button rifling match grade barrels.
I run single point cut barrels anyways so not too worried about it.
Nothing is rigid.
Nothing is rigid.
Does it move enough to matter or even measure?
If just the end is bad what about taking the 2 inch od blank to a #6 contour. Have you measured hominy directions that went?
It all moves but after all said and done.
Poi better thd / not thd?
Nothing is rigid.
Does it move enough to matter or even measure?
If just the end is bad what about taking the 2 inch od blank to a #6 contour. Have you measured hominy directions that went?
It all moves but after all said and done.
Poi better thd / not thd?
this isn't that hard just check before and after with deltronic pins....
Dusty Stevens
Shiner
And when you find that even the finest cut rifled barrels open up by .0002 for 1/2” at the muzzle, does it really matter or can you shoot the difference?
As you all know I work for a button rifle barrel manufacturer that's been around for at least 70 years if there was any merit to the myths of bores opening up even a tenth or so we would be getting hold of the steel mill asking questions we rely on a heat of steel to shrink the same that's why we buy a whole heat when we purchased steel.
Agreed but when the gun fires and the barrel is under the strain of a few thousand psi, even at the muzzle, the bore grows, regardless of how it was made. Rimfire too, but not nearly the same, particularly when the projectile is dead soft lead pushed by maybe a couple of hundred psi at the muzzle vs thousands behind a copper jacketed cf bullet.
That's why I question if a tenth or so of bore growth matters at all in a cf. I don't want inconsistencies in the bore but the bullet will obturate to fit the hole, however big(within reason), that hole gets under pressure.
Hmmm testing my memory! Maybe it was hammer vs button and not cut vs button.
Mike, With a f.b. yes a b.t. decreases in groove dia....
I can't prove it either way other than what can be seen on a fired bullet but I'm not sure that I can agree with that statement. But I do understand what you're saying and you may well be right.
caught bullets in a ballistic lab. from same barrel f.b. and bt. fb come out at groove dia. bt are always smaller ...or to put it another way f.b. are larger in dia. from same barrel.there is gas cutting in grooves of a f.b. not on body a bt has much more including some on body..
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