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.