168gr vs 175gr FGMM bullet drop question?

ArcticFun

Sergeant
Full Member
Minuteman
Oct 29, 2009
220
0
34
Wasilla, Alaska
I was out shooting today with a buddy and we got bored and started plinking at an iceberg with my M40A1. We were using 168gr FGMM and got on target by holding 1 mil high with the BDC set at 1000 yards. Remarkably we were able to shoot the puddle right next to this berg everytime we pulled the trigger, whether he shot or I shot. Then we switched to 175gr FGMM and was able to shoot dead-on with no holdover. Now I can't quite beleive we shot at 1000 yards that well shooting off the roof of my truck so I ask you guys... At what distance is there exactly 1 mil of distance between these two rounds?

For a frame of reference here's a picture. The berg measured 9 mils wide and 3.5 mils tall (27' x 10.5' at 1k if it was 1k). The berg/puddle we shot at is about the middle of the picture and is about level with the end of the stock, just to the left about 1-2 inches if the picture was oriented right.

v2vj0o.jpg


Just for clarification, it was surprising to be hitting the puddle everytime not the berg. Puddle was .5 mil tall and about 3 mils wide.
 
Re: 168gr vs 175gr FGMM bullet drop question?

175s @ 2630 require 10.8 mils @ 1000 yards (1080 alt, 59 deg). Assuming the 168s are traveling at the same speed their lower BC of .462 will require 11.4 mils of elevation. The 168s could be real close to subsonic at 1K, depending on the velocity out of your barrel and conditions, which could account for the additional drop.

Kirk R