what you need to do is shoot at 3 known distances other than the one your zeroed at and measure your drops, then you can either tweak the BC in you computer program till the drops are correct or use a program that allows to to "figure BC from trajectory". Published BC is never dead on everywhere, you need your actual BC and then use that number in your chart, just keep all the info as accurate as you can while figuring the BC.
RR is right on here --- measure the trajectory and back into the numbers.
The Truth Is Not Always Good For Business!!
Guy and myself must have went to the same school because i'm old and think like he does.i'm a firm believer in shooting your gun with it's preferred load at every hundred yards out as far as you will possibly shoot at game.now that i have a place to go farther, i'm gonna shoot as far as my scope will crank just for fun,rocks, groundhogs, coyotes,or anything else that might need shot at. it doesn't take that many rounds. i find a volunteer to walk and give me the impacts.as soon as i get 2 that are pretty close vertically and within a couple inches, i go to the next distance. this has a way of putting confidence in your shooting that can't be matched.scope tracking is another variable.to me, even if you have a computer, you still have to verify all the numbers before you can shoot at game. again, this means shooting at several distances to verify your gun/scope combo will hit at those distances.
Like guy said Old school or only school You NEED REAL FIRE confirmation. To combine what a few have already said not all scopes track the same true 1/4 MOA etc. not all crony's are dead acurate.
I run my numbers, print a drop chart and go to the range and get a solid 100 yard zero.Then go straight to 300, 500, and 1000 yards and and get real numbers for MOA come ups to check against the chart. Then go and tune the program to match my real numbers.
Sometimes my charts are dead on out to 600 but don't run true to 1k so there are little pen corrections with REAL FIRE confirmation at least every 100 yards.
I know it can be tough to find a place to shoot long but you have to shoot at the distance your going to hunt at and often 300 yards isn't long enough to tell you what's going on with the numbers.
As for "flat shooting" just my .02 but it's a term I dont even pay attention to. A 308 Win shoots like a rainbow but will still connect at long range, you dont need fps to be accurate with a good proven set up.
I think once you get things worked out you will quickly meet your goal. Good luck in Nov.
PS make a log and keep good notes on each outing.
"Fast is fine accurate is final"
JBM - Calculations - Trajectory (Basic) is a pretty close program that will get you on target. You will still have to tweak it but it will get you close enough to be on the target. Save some rounds and waiting for bbl to cool down. I zero at 100 then 500 and 1000, then tweak bc until all match. Print it and go shoot the middles to make sure they match. JBM is a great program for free online and wil even print cards. That web sight has alot of good stuff you should check it out.
Well I shot today . The 100.5 gr shoots good at 100 but out at 300 very unstable shooting irratic probally the excessive pressure as someone spoke of due to the longer accubond bullet. When I changed to a 99.0 gr load which shot as good as the 100.5 max load , Without moving the scope, the first shot was dead 0 and 2.0"r windage at 300, the second shot was at the 2.25"r windage but 1.5 high, I pulled the third way low guess I flintched. I let it sit for about 15 minutes and shot two other guns. When I shot the 4th shot, It was 1.5" high at 1.5r windage. So the center of my group is +1" ^ and 2" right.I going to shoot again tomorrow or Saturday waiting long enough to shoot 3 out of a cold barrel. I do not understand why the max load that shot good at 100 would be so irradic when shooting .3xx Well I am going to get it shooting at 300, then shoot at 200 and note my height, then at 100, maybe I found the pill for the ailment. I guess it's trial and error. Thanks all for the replies. Your ideas and input have given me a lot to consider, I'll keep you up to speed with my progress.
what did your groups measure at 100?
what twist ya have?
how many shots did you chrony? (shots in succession unless you let it completely cool get slower.
Here's 2 shots dialed up from a 100 yard zero (the first attemt at long range dialing) at 660 yards in an 11mph crosswind
This was before tweaking my BC in my ballistic program
Born to Hunt, Forced to Work!
Last edited by Ridge Runner; 08-31-2007 at 03:40 PM.