Range Report Ballistic Calculator accuracy??

[Cowtown]

I've been using Strelok for about a year now with my Stevens Model 200 in 308 Winchester. I handload 175 SMKs over 43.5 grains of IMR-4064 and had roughly estimated based on data from my reloading manual that the muzzle velocity was around 2625 FPS. The ballistic calculator really impressed me with how accurate it was all the way out to 500 yards (which is as far as I've shot so far.) All is good...

Well I had the opportunity to shoot my handloads over a chronograph last weekend and found out that they were actually leaving the muzzle around 2745 FPS. A difference of 120 FPS faster... This difference in velocity equals a difference of 6" of drop on my ballistics calculator (Strelok) at 500 yards. I would have missed had I used the true velocity of the load..

What I've learned is that you have to develop your own dope charts for your own load. Not really depressing to me cause I like to shoot and handload so I will enjoy it. I am interested to hear other folks experience has been with this situation and maybe how you handled it..

 

[damoncali]

This could turn into a can of worms, but I think you'll find that if your incorrect velocity got you good results, then something else was wrong- most likely the BC, atmospheric data, or even the line of sight angle. If you nail everything down, you should be dead on at 500 yards with a decent calculator. Basically, you have to hunt down all the errors, which is harder than it sounds. How good is the chronograph? Did you measure the air pressure? How repeatable are BC's from shot to shot anyhow? You get the idea. There is a lot to get right if you want the numbers to be reliable. Guessing won't do it.

 

[Cowtown]

I certainly understand that.. I've input as many variables as I possibly could but need to put some more emphasis on the weather variable for sure...