Posted: 1/10/2012 9:21:00 PM EDT
[Last Edit: eddiesar15][Edited]
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after doing some head scrathing and after using up all my fingers and toes for my mathimatical equations. I think Ive come up with a formula that tells you how many clicks to move your elevation on a 1/8 moa scope.
I know my projectile speed thanks to my chrony and my coeffiency of my projectile thanks to sierra ballistic charts. I found my bullet drop thanks to "bullet drop calculator" (from google). I type,d in all info and it gave me my drop for my load and conditions and what ever distance and intervals I want. So now that i know my drop at what ever distance in inch,s now I need to know how many clicks to move my turret to point of impact with my rifle being zero,d @ 100 yds. This is the formula I came up with. Bullet Drop in inches , times 8 divided by distance = amount of clicks to point of impact (rounded out) example 175gr 308..2552 fps distance is 400yds drop is 38.33 inchs. (drop) 38.55 times( 8 )=308.4 divided by (distance) 400 yrds = .771 ( rounded out to 77) 77 clicks of the 1/8 moa turret. now...every click on the 1/8 moa scope @ 400 yrds = 1/2"...so........lets just double ck myself. .05 times the amount of clicks which was 77 = 385. Im sure somebody out there has already figured out something like this to adj a 1/8 moa scope, so if you have...please dont tell me and burst my bubble lololo |
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rule 1... dont use "clicks"
rule 2 ... dont use 1/8 scopes... they are 99% of the time not even on the turrets example.. a "normal" scope will look like this.. ***1***2***3***4***5 so the the drop is 4.5moa, you set 4.5 on the turret... not 18"clicks" in most 1/8 scope, when it gets back to zero IE: ********8*******9****0 the number are no off and useless. |
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Originally Posted By OhioLongRange:
rule 1... dont use "clicks" rule 2 ... dont use 1/8 scopes... they are 99% of the time not even on the turrets example.. a "normal" scope will look like this.. ***1***2***3***4***5 so the the drop is 4.5moa, you set 4.5 on the turret... not 18"clicks" in most 1/8 scope, when it gets back to zero IE: ********8*******9****0 the number are no off and useless. negative....................Im dead on..............an so is my scope. rule #3 an open mind is a bright mind |
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Originally Posted By eddiesar15:
negative....................Im dead on..............an so is my scope. rule #3 an open mind is a bright mind Counting by clicks is like doing addition by counting fingers. Sure, it will work and can give you a correct answer but when the numbers start to get big it becomes a bit unpractical. Now first.. it does matter what kind of turrets your scope has. If your scope has a hunting style turret that does not have minute of angle marked.. then yes.. you'll have to count clicks. You're formula works good and you can stop reading if you wish :) If your turret looks something like this example, then its much better to think in terms of MOA (Minute of Angle) instead of clicks. 
This turret is like yours in that 1 click = 1/8 moa. I'm not sure which online calculator you use but JBM is pretty good so I used that and plugged in numbers similar to what you posted. The numbers I got from JBM for 400 yards are as follows(I just used a generic setting for the bullet since I don't know the exact numbers you plugged into your calculator so my numbers will differ from yours a little). 175 308 bullet BC of .5 muzzle velocity of 2552 ft/s Range: 400 Drop (inches) -36.6 Drop (MOA) -8.7 So the calculator is already done the math for you. The turrets on my scope go from 0 to 5 and then back to 0. Each number is 1 moa. So a full rotation of the turret (from 0 to 0) is 6 moa. If I continue on to 2, I am now at 8 moa. Each additional click forward is another 1/8th of a moa (or .125). Since we are trying to get to 8.7 and we are already at 8, .7 divided by .125 gives us 5.6, or 5.6 more clicks. So I can do 5 or 6 more clicks. Now, to see how many actual clicks all this rotating gives us: We know each number on the turret is 1 moa, and each moa is 8 clicks. 8 clicks * 8 moa = 64 clicks, plus the 6 extra clicks it took me to get up to .7 moa for a grand total of 70 clicks. So.. I could sit there and count out 70 clicks.. or I can just twist the turret 8 moa's and then count out 6 clicks. Do as you like, but at least for me, counting out 70 clicks takes longer and I'm more likely to screw up my counting somewhere between 30 and 50 clicks ;) The beautiful thing about moa is that 1 moa is 1.047 inches at 100 yards.. so 1 inch very close to 1 moa. When you do your zero at 100 yards.. if your hitting 1 inch low or 2 inches to the right.. you can just adjust your turret 1 moa up and 2 moa's to the left. No counting clicks required :) Hope this helps. Here is a link to the calculator I used: http://www.jbmballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi |
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I had a chance to go out today and I took my 308 and 223 target rifles out.
Ive got 5" round steel swinging targets out to 600. 1 target set up every 100yds. I put my formula to the test today and am happy to say that it works. man i was sweaten bullets today because Ive only tried my formula out with the 308, with a certain load and at 300yrds only. My scope has incremints of 5..... 0 I I I I 5 I I I I 10 and so on. I can quickly dial up what ever i want . not gonna sit there and count click by click I told all my shooten buds about my own calculations and everyone of them was keeing an eye on me as I sent the rds down range. I was smacking the swinger out to 600 easier with the 308 than the 223. there was a slight wind but i still hit. I started at 100 yrds and went to 600 adjusting my scope with my formula ,3 different loads in 308 and 2 different loads in 223. I hope that this formula helps somebody else as well. count by moa or by what ever incremints you choose. it works for me. im not going out to competition nor am I gonna become a sniper anytime soon...just a weekend shooting enthusyist. this is site I use for drop calculation http://www.handloads.com/calc/ the 308 loads that suprised me were Portugese 147gr comming out of the tube at 2910fps. I didnt have to adj. my elevation as much because of the speed of the projectile and the rifle didnt buck as hard either. I have a Titan Muzzle brk on my 308,as well but the Portugese 147 pill were accuratte. not bad for surplus..not bad at all |