Can a muzzle brake interfere with a chronograph?

[DanielLudwig]

Just wondering, I worked up a load for my .300 Wby, and the velocity was on the high side of things, but i didnt question the chronograph, zero'd the rifle at 100yds, dialed up and moved out to 500, shot a very good group 1.5 MOA low! So now I am wondering if maybe my muzzle brake is messing with my data some way? I will lay it all out for you guys and see what you think.
Custom .300 Wby, 28" Krieger brl.
180gr Nosler BT
88.5gr RL25
OAL 3.751
WLR-M primer
4 shot average 3461 fps
scope ht 2.90"
BC .507
zero- 100yds
altitude- 1000ft
500 yd come-up=4.96 MOA?

 

[backwoods83]

It will affect it if your chrony is to close to the muzzle, by that data your showing about 200fps faster than to be expected. With a 28" barrel and that bullet it should a compressed load of RE25 to get those speeds, pretty tightly compressed!

 

[DanielLudwig]

Believe it or not there is still room in the case! I think its mostly due to the fact that my rifle has a very long chamber which lets me load the 180s WAY out. Gonna try the chronograph again this weekend, might even try afew different ones and compare. How far away should I be setting it from the muzzle??

 

[backwoods83]

With a braked weatherby 20 feet at the closest, I wouldn't seat them any further out than having some of the bt below the neck/shoulder junction or right there at it.

 

[cowboy]

With a braked weatherby 20 feet at the closest, I wouldn't seat them any further out than having some of the bt below the neck/shoulder junction or right there at it.

Agree with Backwoods: I use 20'0" from the muzzle of rifle to the center of screen on chrony and then go to a ballistics program and play with velocity at 20 ft. and get get my true muzzle velocity. Just as a side note - if you are using a folding open type chrony make sure it is fully open or you will get weird readings. I even use a small level and get chrony nuts on both ways.