MOA question

[Pahunter]

Ok, ill try that one. I shot my 7mm at the range today, out to 500 yards. Im not impressed with the accuracy

. at 500 bullets are hittin all over the place. The groups out to 300 are excellent, after that they spread out big time. Im thinking about buying Another savage, probally in .308 this time, since its cheaper to reload and my dad already has dies for it.

 

[Brent]

I do a drop chart checking actual drop every 100 yards to beyond the point I plan on hunting, period. An 8' tall sheet of plywood works well. Every round is chroned and plotted on a matching paper target next to me, along with the temp, BP, and also wind and turret notes for each shot.

I rely on the program only to fill the gaps between them with the modified BC to alter trajectory if needed.

Practicing at random ranges for further testing of the programs ability to modify drops with varying temp and BP is the next step. Shooting angles this year is one I really need to work on.

 

[sscoyote]

Brent-- what do you mean when you say modify BC?? Does this mean you change the BC entry in the program to match actual trajectory that you're shooting?? I know some of the reported BC's are not accurate (at least so it seems). I've seen this while trying to test some of the downrange zeros on my Burris Ballistic Plex and Ballistic Mil-Dot reticles calculated by Exbal. They don't seem to match up sometimes, and i'm not sure what to do when this happens to calculate the correct computer generated zeros. I guess i could just continue shooting, and approximate, but i'd much rather work off a model that provides the correct info. Any ideas??

 

[Brent]

I do modify the BC tor correlate the trajectory output to my actual drops, but before I change that BC to force it to fit, I make sure I have a perfect 100 yard zero, and the temperature and BP are known. I also measure the actual inches of drop while shooting on the 8' plywood, no dialing this time, just hold POA at the top edge starting at 300 yards on out. The distance the groups actually fall at each 100 yards should exactly match what you're compensating for when you do the test by dialing on out, or something's wrong with your turret's MOA calibration.

Blain Fields has a ballistics program, he calls it the Precision Shooter's Workbench. It will allow you to leave the BC at what it's published to be, or what you've determined it to be, after actually measuring it by two chronographs. The way it allows you to match the two trajectories is it uses a deceleration constant, or DK. By changing the DK number, you can flatten the curve if you find your bullet actually shoots flatter than the program is predicting it will. Pretty simple to match them up. He also has the program for the new Palm PC's.

[ 03-25-2004: Message edited by: Brent Moffitt ]

 

[sscoyote]

Excellent-- thks.