Veloctity testing

[ctimgo]

I went out today to check on some velocities. They are all over the place. Shooting a 6dasher using Lapua brass, 105vld bullets, Varget powder, and CCI 450 primers. Bore cleaned before starting and time in between shots for the barrel to cool. Here are the velocities. (2867,2900,2904,2886,2895,2909,2950,2923,2993,2940,2959,3039,2953,2994,2901) Accuracy is good at 100 yards but haven't had a chance to stretch it out yet. With those variations in velocity its gonna make a big difference when I do. Any ideas?

 

[savagedasher]

First thing I would do is try a different Crony. Larry

 

[ShootDots]

+1 with Savagedasher... That REALLY sounds like chrono error... I have found on BRIGHT SUNNY days that most chronographs tend to spit out velocities that make little sense.. I have a P.A.C.T. Professional and it "reads" very well in cloud cover and has a difficult time in the sun..

 

[ctimgo]

It does seem to jump around a lot. I will get 5 that are close to each other then the next one will be 50fps higher.

 

[ShootDots]

That, my friend, is your chronograph..

 

[Lapua40X]

Beg, borrow (wouldn't recommend stealing one) a MagnetoSpeed chrono. It's worth every dime (or dollar, depending on your point of view) just for the assurance that I don't have to go back to the range because the sun was too bright, it was too far/too close to the muzzle, etc..

 

[savagedasher]

When your in doubt do like I do. Set your target high enough where your bullet will impact the 1000yd berm watch for vertical on paper and have a friend watch the 1000 yd. With a 50 ft difference that is over 10'' at 1000. Larry

 

[ctimgo]

It is a chrony beta. It is set up 10 feet from the muzzle. Today was cloudy and I used the diffusers.

 

[brxbrad]

Setup is everything.....I believe you have things backwards.....
This is from the Chrony manual.....
5. The Shooting Area. Every Shooting Chrony and Master Chrony comes equipped with an adjustable-size, triangular shooting area (actually an upside down trapezium) from 8"X8" to 14.5"X14.5" (Fig. 2). All Chronys come equipped with four 9.25" wire rods as well as four 6.5" wire rods with brass connectors attached. The 9.25" wire rods are to be inserted at an angle into the outer holes visible on the black plastic boxes of the unit. On bright, sunny (blue sky) days, install the white plastic diffusers on top of the wire rods (to simulate clouds). The photo-sensors are pointed at the diffusers, which create a white background (clouds or diffusers). On cloudy days, use wire rods for alignment, but without the diffusers.

 

[ctimgo]

You know I do remember reading that the diffusers were for use on sunny days. I think you have it nailed. Oh well another reason to go shooting.