Chronograph set up

[Guest]

What is the proper distance, muzzle to screens, for guns like 300 RUM, considering muzzle brakes as well? I hear a lot of variables. I set mine at 10ft. using the Chrony.

Don

 

[Guest]

I've tried as close as 10', but in reality, I end up with muzzle blast affecting the chrony at that distance sometimes, so I usually move it out to about 15' if I have the room to do so.

 

[Guest]

Do you find any loss in velocity at 15ft. vs. 10ft. with that set up?

Don

 

[Antelope_Sniper]

You will get more variation from temperature then you will those few feet.
I put mine where ever the ground is the most level, and it will set the best, around the end of my cord.

 

[Guest]

I've not noticed a huge drop, but then again, I've not compared the two distances on the same day with very many rounds, either. After a while, I just got to where I set the chronograph out at 15' most all the time just because I got tired after a couple of trips of having to wait for the range to go cold to move the chrony. You might lose 5-10fps over that length, but in reality you're going to have that much variation from one round to the next, I suspect.

 

[DrMike]

Don,

All mine are set at twelve feet, unless I am doing ballistic work for Huskemaw. They request fifteen feet. It is easier to compensate for their dials in units of five.

 

[Guest]

Thanks you guys. Dr Mike I think I need to go out another 2ft. making it at least 12ft.

Don

 

[DrMike]

Twelve feet seems to be a minimum when I am shooting "heavies" (30-378, 7.82 Warbird, 300 RUM, etc.). Most ballistic programs will compensate to calculate muzzle velocity. For most situations, it is not a major concern to me; however, with the interest in long range shooting, the precision becomes more demanding as turrets are prepared.

 

[Guest]

Thank you, I will make the adjustments next range trip. Do you see any difference in velocity drop off @ 10-12 ft. or 12-15ft when extending the distance?

Don

 

[DrMike]

Any differences are insignificant and inconsequential. If compensation is required to build a precise turret, the calculation is readily available.

 

[Guest]

Appreciate the reply, thanks for your time today.

Don