7-08 bullet drop
Can anyone calculate the possible drop with the following information out to 400 yards 7-08 possible muzzle velocity 2680 shooting 140 gr nosler bt with 40 grs imr 4064 bal. coefficient is 485 for 140 bt. Gun is sighted in 2 inches high at 100 yards Any ideas? Thanks Best Dave I'm calculating maybe'- on at 200 -9" at 300 and -25" at 400 anybody thinks this is close?
0
-
I think you are close. With Hornady's online Ballistics center I get with 200yd zero.
100yd +1.8"h
200yd 0
300yd -8.2"
400yd -24.0"
That's rough, given std pressure and elevation of 500-1000ft. Temp 60.0 -
quote:Originally posted by skyfish
I think you are close. With Hornady's online Ballistics center I get with 200yd zero.
100yd +1.8"h
200yd 0
300yd -8.2"
400yd -24.0"
That's rough, given std pressure and elevation of 500-1000ft. Temp 60.
Thanks skyfish After I posted the question I went the jmb sight and tried to calculate it and posted the figures it came up with. Any other figures appreciated0 -
cash777,
It seems like the ballistics I use for my 7x57 shooting a 168 Berger/Sierra pushed out at 2660 are:
(+ = add elevation)
100=0
200= +2MOA or -4" POI
300= +5 MOA or -15" POI so far, your numbers match mine
400= +8 MOA or -32" POI This is where your numbers really vary from mine. Maybe if I took the 4" off for a 200 yds. zero and you got 28" it wouldn't be that far off anyway. Anyhow, at those ranges BC isn't going to really come into play that bad but I would still expect your drop to be more @ 400 with that velocity on a 140 gr. bullet.0 -
According to Noslers Ballistic Charts, skyfish is dead on...8.4" at 300 and 24.1" at 400...this was at 2700 fps. 0 -
quote:Originally posted by ECC
According to Noslers Ballistic Charts, skyfish is dead on...8.4" at 300 and 24.1" at 400...this was at 2700 fps.
Well,
There are ballistics charts and there is actual experience. The BC's of the bullets aren't that far off and I chrono my 7x57 loads @ 2660. It was pretty cold when I had to dial those numbers into my scope (+10-+25F). You'll only know for sure if you go and shoot it.0 -
quote:Originally posted by sandwarrior
quote:Originally posted by ECC
According to Noslers Ballistic Charts, skyfish is dead on...8.4" at 300 and 24.1" at 400...this was at 2700 fps.
Well,
There are ballistics charts and there is actual experience. The BC's of the bullets aren't that far off and I chrono my 7x57 loads @ 2660. It was pretty cold when I had to dial those numbers into my scope (+10-+25F). You'll only know for sure if you go and shoot it.
This is true...but case design, bullet weight, and the BC will all play a factor too, don't they.?.?0 -
Eric,
In this case, it's bullet weight, speed and BC. BC has only really started to come into play from 300-400 yds. The bullet weights are different enough that one would expect a little bit of a difference at that range. The funny thing is I don't see the 140 slowing down, my 168 slowed down to the tune of falling down over 4 inches more. The cold may have had something to do with how mine flew and possibly not getting out of the rifle as fast as the day I chronoed. Case design no longer plays a factor once you get the bullet to the speed you shoot them at.
Still, at 400 yds. it's easy enough to adjust while you're still on paper. Shoot it and see where you're at. Get out too far and you have to start finding where your bullets are going and it gets frustrating.0 -
quote:Originally posted by sandwarrior
Eric,
In this case, it's bullet weight, speed and BC. BC has only really started to come into play from 300-400 yds. The bullet weights are different enough that one would expect a little bit of a difference at that range. The funny thing is I don't see the 140 slowing down, my 168 slowed down to the tune of falling down over 4 inches more. The cold may have had something to do with how mine flew and possibly not getting out of the rifle as fast as the day I chronoed. Case design no longer plays a factor once you get the bullet to the speed you shoot them at.
Still, at 400 yds. it's easy enough to adjust while you're still on paper. Shoot it and see where you're at. Get out too far and you have to start finding where your bullets are going and it gets frustrating.
Makes sense...0
Please sign in to leave a comment.
Comments
8 comments