I did have a busy day today but it was a good day because of a scheduling opportunity on my part. But I was able to get to the farm this afternoon for another shooting session. It would be a brief session but beneficial in my mind. Plus
Grouse had shoot the Lehigh 40x215 bullet across two chrono's collecting velocity information which I then plug into a Barnes Ballistic Calculating program.
The shoot, one of the better days for summer shooting it was raining lightly and the temps were in the low 70's - it was really nice. Got to the farm and set the shooting station up. Target at 100 and bench just out side of one of the equipment sheds - which served as the loading station.
I was trying something different today -
SSHooter and I have, and
Grouse have been sharing notes.
SShooter fired the 215 gr. Lehigh in a 1/30 twist the other day using gaining volumes of BH. He really got decent accuracy and may have shed a little of the yawing in the bullet when shot from a 1-30. With that bit if encouragement I to took a 1/30 Knight and the Super DISC to the farm. My goal was to shoot my normal hunting load in both rifles, 120 grains of T7 but the switch up was I was going to use T7-3f to generate a little more velocity with the bullet hoping possibly to take of the yaw.
I did make a mistake shooting this afternoon, as usual I was in a rush, Instead shooting a fouling shot as I normally do and then shooting on a 'semi fouled' as I do hunting - I shot that first shot from the 1/30 into the target. I went ahead then and shot the two rounds and ended up with a 2 1/4' group. Shots 2 and 3 measured 3/4" center-to-center. I then switched rifles and powder, went back to T7-2f - 120 gr. my normal load in a 209 rifle and shot the last group of three. And way you measure it - it measure right at 1" center to center. Both rifles appear to shoot the bullet equally well. But we have learned that not all 1-30 do well with the bullet. Mine and
SShooters work very well when it comes to accuracy 100 yards to 200 yards. But
Grouse's does not do well at all, but that might be due to an eroded vent liner.
Here is the target from today.
After this I went home quickly - I needed to beat Terry home to get some work done.
The next piece of information - really kind of blew my mind... I depend on Grouse to get me the velocity information on the different bullets. Today he gave me this information. The average muzzle velocity of 3 shots was 2090 fps with 120 gr. of BH at about 700' of elevation. The average velocity of the bullet at 100 yards was 1870 fps. With this information I feed it into the Barnes Ballistic Calculator, which has always proven to be a very reliable program not perfect but pretty darn good.
This is the sheet the program produced. When sighting in a I use a PBR (Point Blank Range Calculation) and in most cases I request a 6" PBR. This gives me a bullet path that will not be greater than 3" high on the target or 3" low by holding directly on the target. In this case the zero range will be approximately 174 yards and maximum range and being 3" low would be at 216 yards.
