rojodiablo
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- Sep 17, 2011
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To Appicola's post above; he is correct in that gas block alignment can be a real source of problems. Seems though everything should line up the same, often it's a case of one time or another being off by a mere.03, and if that is enough to pinch the flow of gas, then it causes problems. Also, we can (And DO) set gas blocks the tiniest bit crooked from time to time. Instant problems arising.....
As to Duggies' post on how the muzzle break works; they DO work two-fold, in redirecting the vented gas. But that's about where the story went off a bit.....
A muzzle break does NOT make a bullet travel further. They do not reduce the gas pressure in front of the bullet. It's simple math: The hole is .30, and the gas coming out is going X FPS. Until that gas exits the barrel, there is no reduction in pressure. The vented gad would see a venturi effect in the VACUUM of the gas behind the bullet, at the tail end of the venting. But the fastest way the gas could (And does) vent is to open air. High pressure meets low pressure, and the greater volume always draws the lesser volume to its' level, or dissipates it to a new equilibrium.
The venting effect under pressure is scrubbing a small portion of the gas pressure created; the vast majority is still going straight out the hole in the front. The greater the diversions and compartmenting the gas exiting the barrel, the longer the period in which the gas takes to equalize to static atmospheric pressure.
The venting is purely under pressure, so it is not reducing any said pressures; it's more relocating them/ redistributing them. Which is why there are SO many muzzle break designs, and it is why so many are not really effective. What can be said of muzzle breaks in general terms is they are designed to do different jobs, and as such, different breaks make the rifle act differently. Some vent gases to the sides hard, to use the gas pressure to push the barrel downward and get the rifle back on the sight picture quicker. Some are designed to diffuse the muzzle blast to throw much less signal (Dust cloud). Some are designed to reduce felt recoil by venting back hard, which has the effect of pulling the rifle forward, lessening the buck of the recoil.
NONE of them can do all the stated goals. And the further they try to cover these bases, the further they really fall from doing any 1 thing well.
It's kina like the old saying; Good, fast, cheap. You can pick any 2. You lose the 3rd one in the process.
As to the cases in question; the steel cases are a pretty soft annealed steel, and the Teflon coating does a very good job unless the case has rust on it. But a corrosion coated brass casing is also problematic, so it's an equal issue. As to powder type/ burn speed- this I believe is the primary problem when any semi auto gun is tuned to a specific range of operating. And this is not by any means limited to rifles; most of us have had a 1911, or a 9mm which was just not happy with some kind of ammo, and lots of range reloads are a surefire way to make a great pistol become a troublesome paperweight.
My personal thoughts on AR10 platform rifles is this: Many are designed around high quality, very well proven and consistent hunting ammo, or even match grade target shooting ammo. (Something you should understand; often match grade ammo is a little slower and slightly less hot than a premium hunting round because they are striving for consistency above all else. To a bench shooter who is lurking around 600-1000 yards, 50FPS on top means nothing, if he can get within 5FPS time after time and have stellar consistency for his efforts.)
But to most zombie target, assault pumpkin fighters, if we want to shoot the rifle more than 20 times today, we run less expensive ammo. And therein lies the crux; NATO 7.62 x51 is usually in the 2730 FPS range, with 2425 ish ft.lb of energy....... DELIVERED VIA A 24" BARREL.
Now, your premium Federal Nosler ballistic tip whitetail eliminator scoots out of a 20" barrel at 2820 FPS, and 2680 ft.lb of energy. I have found Wolf/ WPA ammo to be pretty close to the speed of standard 7.62 ammo. Not going to stand in front of one to test the energy delivered....
but when shooting steel, the impacts are very similar between NATO ammo and Wolf ammo.
Now, imagine how far off those marks your actual realized velocity and energy are when you reduce down to a 16" barrel........ When shooting a 308 Ballistic tip from a 24" barrel, the pressure is maxed, and you would see really close to 3000/ 3050FPS.
If a rifle is designed with the pressures of a NATO caliber in mind, they are likely to eat almost any ammo fed to them. The further you stray from that, the narrower the range of effective cycling gets. 24" barrel, 2730. 20" barrel, 2820. It's a LOT more than just 90FPS, and 240ft.lb of energy.
So I hope this math journey gives you a little more understanding just how far off a rifle could be from an ideal operating range. And you can get the jist of how maybe a muzzle break is trying to perform a given task, and it winds up working against the rifle it got mounted onto.
FWIW, I never consider a 16" barrel to be a long range target barrel, for nothing more than the lost velocity. And there is NO muzzle break that will increase the distance by which a bullet will fly. There is NO muzzle break that will increase the speed of a bullet leaving the barrel. And finally, most muzzle breaks are designed with 20-24" barrels in mind. So the chances of them having an unexpected effect on a rifle is understandable, given you look at the math via velocity, energy, and imagine the difference in developed pressure at the barrel, and the timing involved. The window of time is tiny; by the time you imagine the round firing and seeing the reloading process in your mind, that amount of time has allowed that bullet to travel some odd??? 1000 yards downrange.
As to Duggies' post on how the muzzle break works; they DO work two-fold, in redirecting the vented gas. But that's about where the story went off a bit.....
A muzzle break does NOT make a bullet travel further. They do not reduce the gas pressure in front of the bullet. It's simple math: The hole is .30, and the gas coming out is going X FPS. Until that gas exits the barrel, there is no reduction in pressure. The vented gad would see a venturi effect in the VACUUM of the gas behind the bullet, at the tail end of the venting. But the fastest way the gas could (And does) vent is to open air. High pressure meets low pressure, and the greater volume always draws the lesser volume to its' level, or dissipates it to a new equilibrium.
The venting effect under pressure is scrubbing a small portion of the gas pressure created; the vast majority is still going straight out the hole in the front. The greater the diversions and compartmenting the gas exiting the barrel, the longer the period in which the gas takes to equalize to static atmospheric pressure.
The venting is purely under pressure, so it is not reducing any said pressures; it's more relocating them/ redistributing them. Which is why there are SO many muzzle break designs, and it is why so many are not really effective. What can be said of muzzle breaks in general terms is they are designed to do different jobs, and as such, different breaks make the rifle act differently. Some vent gases to the sides hard, to use the gas pressure to push the barrel downward and get the rifle back on the sight picture quicker. Some are designed to diffuse the muzzle blast to throw much less signal (Dust cloud). Some are designed to reduce felt recoil by venting back hard, which has the effect of pulling the rifle forward, lessening the buck of the recoil.
NONE of them can do all the stated goals. And the further they try to cover these bases, the further they really fall from doing any 1 thing well.
It's kina like the old saying; Good, fast, cheap. You can pick any 2. You lose the 3rd one in the process.
As to the cases in question; the steel cases are a pretty soft annealed steel, and the Teflon coating does a very good job unless the case has rust on it. But a corrosion coated brass casing is also problematic, so it's an equal issue. As to powder type/ burn speed- this I believe is the primary problem when any semi auto gun is tuned to a specific range of operating. And this is not by any means limited to rifles; most of us have had a 1911, or a 9mm which was just not happy with some kind of ammo, and lots of range reloads are a surefire way to make a great pistol become a troublesome paperweight.
My personal thoughts on AR10 platform rifles is this: Many are designed around high quality, very well proven and consistent hunting ammo, or even match grade target shooting ammo. (Something you should understand; often match grade ammo is a little slower and slightly less hot than a premium hunting round because they are striving for consistency above all else. To a bench shooter who is lurking around 600-1000 yards, 50FPS on top means nothing, if he can get within 5FPS time after time and have stellar consistency for his efforts.)
But to most zombie target, assault pumpkin fighters, if we want to shoot the rifle more than 20 times today, we run less expensive ammo. And therein lies the crux; NATO 7.62 x51 is usually in the 2730 FPS range, with 2425 ish ft.lb of energy....... DELIVERED VIA A 24" BARREL.
Now, your premium Federal Nosler ballistic tip whitetail eliminator scoots out of a 20" barrel at 2820 FPS, and 2680 ft.lb of energy. I have found Wolf/ WPA ammo to be pretty close to the speed of standard 7.62 ammo. Not going to stand in front of one to test the energy delivered....
but when shooting steel, the impacts are very similar between NATO ammo and Wolf ammo.Now, imagine how far off those marks your actual realized velocity and energy are when you reduce down to a 16" barrel........ When shooting a 308 Ballistic tip from a 24" barrel, the pressure is maxed, and you would see really close to 3000/ 3050FPS.
If a rifle is designed with the pressures of a NATO caliber in mind, they are likely to eat almost any ammo fed to them. The further you stray from that, the narrower the range of effective cycling gets. 24" barrel, 2730. 20" barrel, 2820. It's a LOT more than just 90FPS, and 240ft.lb of energy.
So I hope this math journey gives you a little more understanding just how far off a rifle could be from an ideal operating range. And you can get the jist of how maybe a muzzle break is trying to perform a given task, and it winds up working against the rifle it got mounted onto.
FWIW, I never consider a 16" barrel to be a long range target barrel, for nothing more than the lost velocity. And there is NO muzzle break that will increase the distance by which a bullet will fly. There is NO muzzle break that will increase the speed of a bullet leaving the barrel. And finally, most muzzle breaks are designed with 20-24" barrels in mind. So the chances of them having an unexpected effect on a rifle is understandable, given you look at the math via velocity, energy, and imagine the difference in developed pressure at the barrel, and the timing involved. The window of time is tiny; by the time you imagine the round firing and seeing the reloading process in your mind, that amount of time has allowed that bullet to travel some odd??? 1000 yards downrange.
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