out at oil cap you need to be awere of the lights on the tv towers messing with your chomo readings.
This problem is often caused by the glint of ambient light on the bullet. A fabric diffuser can often be helpful. Line up the chronograph first- get a reading to prove its aligned.
Form a "tunnel" as follows:
Push 4 pieces of 5' long 1/2" emt (electrical conduit) into the ground in a (roughly) 24 X 68" rectanglular pattern with the chronograph screens in the center. The long axis (68") is aligned with the shooting position and the target, the chronograph is more or less centered on the 24" dimension. Connect the top of each pair of poles on the long axis with a 3/8 X 1 1/2 72" lath. I now use bolts to make this connection, but for years simply used zip ties. If it's a windy day you'll also have to brace the 24" dimension near the top. Drape a piece of mosquito netting or other very, very sheer, matte fabric about 72 X 72" over the lathing . Gather the corners of the fabric and zip tie one corner to each pole. This takes only a few minutes to erect with practice.
Comments:
1. Shadowrider's comment about making sure that you've got enough distance between the muzzle and the first screen is important. Blast can cause severe problems.
2. Blitzfike's comment about the source of the lighting is also relevent.The use of a diffusion tunnel is often helpful here.
3. Oehler's chronographs use 3 screens-channels 1 & 2 are compared with channels 2 & 3. The chronograph reports the difference and will frequently "catch" this sort of problem.
regards,
Bob
Form a "tunnel" as follows:
Push 4 pieces of 5' long 1/2" emt (electrical conduit) into the ground in a (roughly) 24 X 68" rectanglular pattern with the chronograph screens in the center. The long axis (68") is aligned with the shooting position and the target, the chronograph is more or less centered on the 24" dimension. Connect the top of each pair of poles on the long axis with a 3/8 X 1 1/2 72" lath. I now use bolts to make this connection, but for years simply used zip ties. If it's a windy day you'll also have to brace the 24" dimension near the top. Drape a piece of mosquito netting or other very, very sheer, matte fabric about 72 X 72" over the lathing . Gather the corners of the fabric and zip tie one corner to each pole. This takes only a few minutes to erect with practice.
Comments:
1. Shadowrider's comment about making sure that you've got enough distance between the muzzle and the first screen is important. Blast can cause severe problems.
2. Blitzfike's comment about the source of the lighting is also relevent.The use of a diffusion tunnel is often helpful here.
3. Oehler's chronographs use 3 screens-channels 1 & 2 are compared with channels 2 & 3. The chronograph reports the difference and will frequently "catch" this sort of problem.
regards,
Bob
Got any pics Kurt? I've had the same problems as everybody else is having, and would sure like to get something consistant, no matter what kind of day it is.
It will be late next week before I can post any pictures. Basicly I built a ply wood box 2'X2'X4'. put the chrono sensores in the bottom and placed a 50 watt D.C. bulb above each sensor, (got the bulbs from an R.V. store) I then cut up an extention cord and put on aligator clips on the wire ends. I just pop the hood of the truck open, clip the aligator clips to the battery and the lights light up. I went with D.C. lights as they are the most uniform light source. Be sure to paint the inside of the box FLAT BLACK! if not it gets too much light scatter and will only read every 4th-5th round. Then just cut a 4" diameter hole in each end for the bullets to pass through right over the sensores and you are in business. I will post up some pictures when I return to OK. KurtM
That sounds remarkably like a match chrono setup.
Would you be willing to shoot a few of my reloads across it?
I have beer.
Would you be willing to shoot a few of my reloads across it?
I have beer.
I've found it best to wait till early morning, late evening, or an overcast day to chrono. I will keep the chrono in the shade and find my results to be pretty consistent. I've never used the sun shades going this route.
