Dial a Dog
- Thread starter .280 Remington
- Start date
Ridge_Runner
Handloader
- Sep 29, 2006
- 1,394
- 760
sight height was measured with a dial calper, ( measure total height of scope bell to bottom of barrel, then subtract 1/2 the scope and barrel diameter) am using current station pressure and leaving the altitude on "0". I have to tweak most bullets BC to make my chart match trajectory, but the 6.5 139 lapua scenar was dead on using published BC of .615. This is what works for me, I've tried the other methods and always hit high, even using the G7 BC with point mass software.usmc 89":2krl6den said:
RR
I can't seem to get the 160 Ab to match very well out of my STW. We have ranged all the targets and for some reason I have to drop the BC from .531 to .435 to get it to work out right. I'm not sure why, maybe I need to try the RR method of getting scope heigth. I put my alt. in, but I don't screw with the atmosopheric pressure. Should I be?
Ridge_Runner
Handloader
- Sep 29, 2006
- 1,394
- 760
ya need accurate BP numbers, it is the single most important piece of data ya gotta have,jmad_81":jggmk7hj said:
BTW I run the bc of the 160 AccuBond at either .62 or .58 to match my trajectory, and have used that number (.62) to take 46 deer from 307 to 1350 yards.
RR
Desert Fox
Handloader
- Aug 14, 2006
- 1,965
- 3
There's lot of variables to consider when doing your calculation. Scope height is important but not as critical. Make sure your scope tracks well. Verify if your scope elevation dial is calibrated in either MOA or IPHY.
Which Ballistic Program/Calculator are you using?
i use the jbm ballistics system with litz bc assessments, take the current conditions and put them into an altitude density calculator to get the altitude condition. my charts are usually spot on when that and the other measurements are done correctly. i am just wondering if you are fudging your bc values to coincide with your chart and impacts if that would not throw off your windage corrections? apparently not if your shooting deer past the 1k mark.
Desert Fox
Handloader
- Aug 14, 2006
- 1,965
- 3
jmad_81":vur7x7tx said:
I'm not familiar with those program. I'm pretty sure they're as accurate as any out there. I use Ballistic FTE on my I-Phone. It uses JBM Ballistic Engine for it's computation. Remember your result is only as accurate as the data your inputing.
Ridge_Runner
Handloader
- Sep 29, 2006
- 1,394
- 760
exactly keep every bit of data that you can control as close to perfect as possible, then the ones you can't control won't screw you up quite as bad.Desert Fox":2gttgckq said:
so ya measure scope height, shoot a known MV, keep your atmospheric conditions dead on then the only thing I can do is tweak my BC till my chart matches what I'm actualy shooting. sure I can move the velocity around and make my chart right, but then if not using my actual BC I might be on at 400, 500, 600 yards, the wrong BC will make ya miss bad at 800,900,and 1k.
RR
