Re: bullet ogive measuring for mile shooting
When pushing my 223 and 6.5 to a mile and beyond, I found that bullets, more then anything, can give different results.
Simply put, some bullets don't mind going subsonic. others don't.
For my 223, I shot 80gr Amax and Bergers, and 75gr Amax. All loads dialed in for min. vertical and really good accuracy. Even the muzzle velocities were very similar. The Bergers shot consistently smaller groups at 200yds.
The bullets should start to go transonic around 1200ish yds. At 1400yds, all bullets were still right on target. However, by 1700yds, the Berger was definitely vertical stringing. Some groups severly.
Both amax on the other hand continued to be consistent and accurate. At 1 mile, I got a very nice string in my video on a sub MOA rock.
Wind is my biggest headache. Doesn't take much to move you around and wind will come in various directions. Lots of wind flags infront/behind/ and the side of the target area.
The second shot in my video that lands short was due to a headwind gust I did not adjust for.
As for the 6.5, I am presently shooting 139gr Lapua's at 2900fps in my Mystic (260improved variant). I have had no problems reaching 2300yds with it accurately.
I am working on getting more elevation so I can try and get out to 2600yds. Every 50 to 100yds, at that range, is a real challenge.
I do not do anything to my bullets except take them out of the box, load and shoot.
From watching other rifles pushing bullets at long ranges, it shows that results are not consistent. One combo works in one rifle but not in another. The 308 is the most common case.
I saw a wonderfully accurate 308 pushing 175gr MK's fall apart at 1400yds. Yet, another with similar specs get out to 1800yds. Myself, I have pushed 155gr Amax beyond 1400yds with no issues at all.
I offer nothing quantitative or conclusive except to say that if a rifle/load combo is accurate with little vertical at 1000/1200yds, any failures further out is simply a problem with that bullet/rifle combo and its ability to go subsonic.
Try another bullet and it might solve your issues. In general, Amax seem to make the trip more often then not. Looks like the 6.5 Lapua will do the same.
Good luck with your quest. MOA at 1 mile is a huge feat but I know it is possible.
Just helps if you can find a calm day.