Can muzzle brakes reduce or increase ES/SD?

[JB.IC]

It would be an easy test.
Say take an 18” 308Win. One load with Varget and another load with say H50BMG; all else the same. Shoot enough to have a stable variance distribution, say 20-30 rounds each under the same conditions. See which one has the lowest SD.

 

[Emerson0311]

yeah...since I made the first post, I watched another EC's podcast and it appears that in the video I posted, he's talking about POI shift not ES/SD. so I misunderstood him.

But regarding unburned powder, that's another interesting point as well. does it cause high ES/SD? from time to time, I hear it does. and to me, it makes sense.

if the barrel is long enough so all of the powder is burned before the bullet exit the muzzle, then the push should be exactly the same each time. but if the barrel is not long enough, then by the time the bullet exits the muzzle, the amount of powder that has been burned up to that point might vary. it could be 91%, 92%, etc. each time and that causes muzzle velocity to deviate.

so if the above is true, then long barrels are inherently better in achieving lowest possible ES/SD, as long as they are long enough for a complete burn.

Mark & Sam made a video on "optimal barrel length" in which he said, if you continue to add barrel length after the powder has been burned completely, then that won't speed up the bullet and will only slow it down due to friction. so is it wrong to say:

whatever your current's barrel length is, if you replace it with a barrel that is 1 inch longer, and still see a speed increase, then that must mean the current barrel is not long enough for a 100% burn. because if it was long enough you would have gotten a speed decrease, not increase. and your ES/SD will never be as low as they could have been with an "optimal length" barrel?

I have asked 3 different gunsmiths and they all told me no. barrel length does not affect ES/SD. but what does everyone think?

Well, if the same ammo in a 24” has lower SD than in a 20”, maybe? Data integrity is usually less solid than “conclusive evidence”. I’m doing this now, but honestly, I don’t care enough to pretend to be some kind of grass range scientist.

 

[JerkyFreak]

yeah...since I made the first post, I watched another EC's podcast and it appears that in the video I posted, he's talking about POI shift not ES/SD. so I misunderstood him.

But regarding unburned powder, that's another interesting point as well. does it cause high ES/SD? from time to time, I hear it does. and to me, it makes sense.

if the barrel is long enough so all of the powder is burned before the bullet exit the muzzle, then the push should be exactly the same each time. but if the barrel is not long enough, then by the time the bullet exits the muzzle, the amount of powder that has been burned up to that point might vary. it could be 91%, 92%, etc. each time and that causes muzzle velocity to deviate.

so if the above is true, then long barrels are inherently better in achieving lowest possible ES/SD, as long as they are long enough for a complete burn.

Mark & Sam made a video on "optimal barrel length" in which he said, if you continue to add barrel length after the powder has been burned completely, then that won't speed up the bullet and will only slow it down due to friction. so is it wrong to say:

whatever your current's barrel length is, if you replace it with a barrel that is 1 inch longer, and still see a speed increase, then that must mean the current barrel is not long enough for a 100% burn. because if it was long enough you would have gotten a speed decrease, not increase. and your ES/SD will never be as low as they could have been with an "optimal length" barrel?

I have asked 3 different gunsmiths and they all told me no. barrel length does not affect ES/SD. but what does everyone think?

Wrt barrel length, once the powder has completed burning, the acceleration reduces until the in-bore pressure is equal to the bore friction. Only then it will start to slow down. That equilibrium point is much further down the barrel than you suspect.

As for ES/SD, just because you donot have 100% combustion does not equal ES/SD numbers worse than full combustion.

Also, any device that strips the muzzle blast or reduces the amount of muzzle blast passing the bullet on muzzle exit should give some improvement to the ES numbers solely to the fact that it will reduce bullet upset on launch. This will reduce and equalise the time until the bullet points in a direction of minimum aerodynamic forces; i.e. apparent improvement in BC. Whether this improvement is noticable is debatable.

 

[Doom]

….

Also, any device that strips the muzzle blast or reduces the amount of muzzle blast passing the bullet on muzzle exit should give some improvement to the ES numbers solely to the fact that it will reduce bullet upset on launch. This will reduce and equalise the time until the bullet points in a direction of minimum aerodynamic forces; i.e. apparent improvement in BC. Whether this improvement is noticable is debatable.

Yea, I'm not convinced that the reduction in blast will actually show up as reduction in SD or ES. However, I did want to mention that the effect described above is true for boat tailed bullets but it doesn't happen with flat based bullets!

 

[markl323]

It would be an easy test.
Say take an 18” 308Win. One load with Varget and another load with say H50BMG; all else the same. Shoot enough to have a stable variance distribution, say 20-30 rounds each under the same conditions. See which one has the lowest SD.

in my 27" 300 PRC barrel, the fastest powder (N565) has the lowest ES/SD. the other two are H1000 and Retumbo. coincidence?

 

[JB.IC]

in my 27" 300 PRC barrel, the fastest powder (N565) has the lowest ES/SD. the other two are H1000 and Retumbo. coincidence?

It could be a consequence of too many things to say the faster powder definitively has lower dispersion (it could be a good lot for one powder and bad lots for the other). I am not saying that your observations are incorrect. You will know your system better than anyone here because you actually own it and use it.

To have confidence inspiring evidence, you really need to shoot around 20-30 rounds per powder (in a randomize order) and then compare their variances. Then you need to repeat your test for confirmation. You also need to ensure you’re using a reliable measuring device and measuring each shot the same way. Ideally, all rounds would be fired under the same conditions and the firing order of the rounds would be random.

 

[Doom]

It could be a consequence of too many things to say the faster powder definitively has lower dispersion (it could be a good lot for one powder and bad lots for the other). I am not saying that your observations are incorrect. You will know your system better than anyone here because you actually own it and use it.

To have confidence inspiring evidence, you really need to shoot around 20-30 rounds per powder (in a randomize order) and then compare their variances. Then you need to repeat your test for confirmation. You also need to ensure you’re using a reliable measuring device and measuring each shot the same way. Ideally, all rounds would be fired under the same conditions and the firing order of the rounds would be random.

Even then you would want others to test in much the same way. If you shoot round robin does one powder interact with the other and affect the fouling?

 

[JB.IC]

Even then you would want others to test in much the same way. If you shoot round robin does one powder interact with the other and affect the fouling?

It’s a serial correlated system, so no test will be perfect. Especially, when the system has a short life cycle like a 300PRC.

Also, random assignment would be difficult as well considering how powder is dispensed. It’s not reasonable to constantly swap powders to satisfy random assignment. Ensuring minimal effects of say scale drift or static are difficult. He’d need to check his scale at some interval. To be clear, I’m brining this up because someone could say one powder is more variable than the other and it could have been simply static build up during that run. If someone doesn’t know to look for that measurement error, then they’ll think they found something when they didn’t. Or something as simple as say a different lot of primers could be a culprit.

Then there’s the issue of random assignment of the shooting environment and bore conditions.

With each shot, the system changes slightly. The best anyone can hope for is to average out the lurking variables thru randomization.

As far as other shooters conducting the test in an attempt to draw a similar conclusion, I’m less concerned about generalization. The random effects of everyone else’s system and the current state of their system might be too large (very large) to draw a conclusion. By the time there is some sort of conclusion, we will find out that everyone had different lots of everything. Different barrel lengths, bullet preferences, manufactures, gun smiths, chamber dimensions, etc. At the end of the day, I only care about the barrel I have and the bullets, powder, primers, etc. that I use. I only need my results to generalize to my system.

 

[Ledzep]

Only way would be extremely short barrels with a device specifically designed to make it worse. You will still have unburned powder at muzzle exit regardless of the system but it's less than 5% total powder mass on anything over 14.5-16" 99% of the time unless you do it very wrong.

The bulk of velocity and velocity variation happens in the first ~10" or so, and obviously there are exceptions and slants on this statement but that's generally the case. By the time the bullet uncorks from a 24-28" barrel the combination of exit pressure, inertia, and velocity mean that no matter what you do you're not changing the MV of that shot by much at all regardless to what your muzzle device is doing to the exit flow. Don't have any idea how a static device would swing ES to be better or worse, either...

Dispersion, yes 100% you can make a rifle shoot differently with different devices.

 

[JB.IC]

Only way would be extremely short barrels with a device specifically designed to make it worse. You will still have unburned powder at muzzle exit regardless of the system but it's less than 5% total powder mass on anything over 14.5-16" 99% of the time unless you do it very wrong.

The bulk of velocity and velocity variation happens in the first ~10" or so, and obviously there are exceptions and slants on this statement but that's generally the case. By the time the bullet uncorks from a 24-28" barrel the combination of exit pressure, inertia, and velocity mean that no matter what you do you're not changing the MV of that shot by much at all regardless to what your muzzle device is doing to the exit flow. Don't have any idea how a static device would swing ES to be better or worse, either...

Dispersion, yes 100% you can make a rifle shoot differently with different devices.

If I had time, I’d cram some H50BMG into an 18” 308WIN. Just for fun.