Missing at longer ranges?

[wildman]

Most of you who know me know I mostly shoot an 03-A3. I do own some very fine M1s and lately I have been shooting one of them.  My groups look great at 25 yds and am able to confirm my sights at 200 and 300 yds without difficultly. Shooting at longer distances I had trouble getting hits. What was up?

A week ago at the high power match I shot a fine score at 500 yds with my sight set for 400+2. I don't tell you that to brag but 20 rounds is good conformation of sight settings so I am sure its correct. Remember a 500 yd bull is pretty big so POA POI setting is less. Yesterday I set up targets at 2,3, and 400 yds plus 450. Sure enough 200 and 300 are right on but the bullet drop after 300 is much less that predicted. The 400 yd setting was 300+2 and 450 is 3+3.

So what? The lesson is that there can be a large difference in ammo. I wouldn't have thought it would be that great. HXP is what I was shooting it is M2 ball and meets US specs. but is loaded with a hot weather friendly powder. It will be interesting to see what the difference is if any when it cools down this fall.   

If you are shooting well at shorter ranges but not getting the hoped for results at longer ranges you might want to look at your ammo.

[1shot]

I ran into something similar at BC3 with Radway Green ammo.  Though it is purported to be standard M855 Ball, It had a very significantly flatter trajectory than expected.  So much so, that at 400 yds I was 3 clicks under, and at 500 yds I was 5 clicks under.

It was dead on at 25, 100, and 200, but a bit high at 300.  It would have been easier to figure out the problem had I zeroed at 300 instead of 25, since that would have revealed a slightly low strike at 200, and a pretty high strike at 400, whereupon I could have adjusted for the flat trajectory.

But anyway, long story short and bottom line, at BC3, the Radway Green fired with a VERY flat trajectory from my 20" AR15 A2 HBAR 1:7.  I can only imagine that it was designed to retain the proper ballistic trajectory from an M4 Carbine (which makes less muzzle velocity)

[Old Dog]

I ran into a similar thing once in the Army in the late 70's.  On one trip to Fort A. P. Hill for qualification I found myself aiming below the pop ups even at 300 yds.  Normally I aimed in the dirt at 50, dead center at 100 to 200 and at the head at 300.  I found myself missing at 300 and after some "searching" fire (we did not shoot paper at ranges farther than 25 meters, we shot pop ups in Trainfire) I figured out where to aim.  It seemed that compared to previous range "visits" with my favorite TRW M14 the bullet came out of the barrel and just kept "climbing upwards".  Boy I wish I still had that rifle.  It was a great shooter and never broke on me, not in four years.  It was like leaving a part of me behind when I ETS'd.  Good thing I had my M1A by then to ease the pain of separation.

Which all means, just like wildman said - go to the range, shoot paper, confirm you rifle and your ammo's trajectory and write it down where you won't loose it - ammo ID, rifle ID, sight settings, range, temperature/weather conditions.  It's your life, do everything you can to make it last as long as possible.

[Nickle]

Back when I used to actively shoot Bench Rest, I even would notice different burn rates of the same powder (same lot even) from Summer to Winter. Winter loads would be some hot in the Summer, especially when using Win 748 (which is the same basic powder as 846 and 844, except data won't exactly interchange). Zero was definitely different, and it wasn't the rifle, it WAS the ammo.

[kissell]

Not to seem knowledgable, though, try chronying several loads for consistancy then go onsite to JBM Calculations and Trajectory. This will give you, once you feed in the data, correct drop for your bullet. One given, if your loads leave the barrel at a consistant speed, you have no control upon exit. Thence they should react the same at same distances barring wind changes. Now it seems that you may have miss calculated the drop of you specific load. Printed data as far as what the velocity should be may vary greatly from the velocity produced from your rifle. Also do not barr-out wind as to it's effect. At 100-200yds. wind effects larger bullet minimally, but, at 400yds. and up look out. Nothing to see 40" drift from gusty winds. Later.

[Dirty Bill]

I roll my own,and I now use Varget. It is supposed to be unaffected by temperature change.