Muzzle Velocity question for Nosler

[Mark Z]

What distance do you place your chronograph form the muzzle to determine the muzzle velocity listed in your reloading manuals? Does a few feet make any appreciable difference (10 feet versus 15 feet)?

Thanks,
Mark

 

[JD338]

I always go 15' so I do not get any muzzle blast interference from my 338 RUM. I have an Ohler 35.

JD338

 

[Mark Z]

Thanks JD338.

 

[Guest]

If you want a fair idea of what the difference is regarding distance from the muzzle, try setting up your chrono 10' off the muzzle, and then 20' off the muzzle. Use the two measurements to figure the curve, so to speak. Sometimes the readings will surprise you.

 

[C.Smith]

If you want a fair idea of what the difference is regarding distance from the muzzle, try setting up your chrono 10' off the muzzle, and then 20' off the muzzle. Use the two measurements to figure the curve, so to speak. Sometimes the readings will surprise you.

Can you say what is surprising? Inquiring minds what to know.

Corey

 

[Mark Z]

I wanted to know what distance NOSLER used in their testing to get the velocity listed in their manuals so I could be consistent with their procedure. Does anyone know what NOSLER does?

 

[C.Smith]

Most Chronographs that I know of state you need at least ten feet from the muzzle. That would be my best guess.

Corey

 

[Guest]

If you want a fair idea of what the difference is regarding distance from the muzzle, try setting up your chrono 10' off the muzzle, and then 20' off the muzzle. Use the two measurements to figure the curve, so to speak. Sometimes the readings will surprise you.

Can you say what is surprising? Inquiring minds what to know.

Corey

I think the biggest surprise was that some of my rifles read better (more consistently without error and with less variation) at one distance versus the other. Most read better at 15', but one reads better at 10'. Not sure why. Other than that, it is surprising to figure what little difference there is in recorded velocity versus actual muzzle velocity for some rounds, while with others it is markedly different. I suspect BC is the culprit, but that also means there are some bullets with way lower BC than advertised. (I use the two readings to extrapolate true muzzle velocity, which is 'mostly' accurate as a calculation, but not exactly.)

 

[Ol` Joe]

I saw a thread reguarding correcting the chrono velocity to true muzzle velocity once, but can`t remember where. As I remember the answer was a chrono set 12-15 ft from the muzzle likely was showing more extreem spread in velocity then existed between the two. It simply wasn`t worth worrying about the difference in most instances.