Went out to shoot. Shooting every 100 yards on my steel target then a 3 shot group on my paper target. Doing fine, getting first shot hits on steel! Got out to 650 yards (this is about where things get harder so I went to 50 yard increments) and I miss my steel, 3 times in a row. Shoot a group on my paper target and go check my target. I am 12" high! WTF? Go back and check my scope, check my dope and move my elevation down 1 moa and I am now 1 moa high! Shooting steel and such anyway I change to a new box of ammo (I reload) and now I get 6" low!!
Double WTF! Shoot some more and am back on my charted dope again, all has turned to normal.
Got home and looking at my notes. 2 moa high. There has GOT to be a reason. Not just my lousy shooting either. It was consistent for a while. I check my gun, check my scope. All is well. I am thinking it was just that one box of ammo. Wondering if my scale might be off. Make a note to buy some checkweights.
So I am now reloading, removing primers and prepping my brass that I shot that day. I get to one box and the brass feels a bit different. I notice it is Lapua brass (I don't mix my brass I keep it in a case of 20). I had bought some factory ammo that used lapua brass. All my other brass is Hornady. Hmm, I say, must be it. Lapua brass can cause 2 moa of elevation change! I gotta get some more of this stuff!!! Then I look at the label I put on plastic box. I used different bullets also! I remember now! I loaded 155 Bergers instead of 155 Lapua Scenars. So that is it! Going to put any non-standard loads into different colored ammo boxes from now on!
I just got finished working with JPM ballistics and making the BC .6 instead of .5, adding 70 fps (Lapua brass is thicker, less case capacity so more pressure) to my Lapua Scenar ballistics table. I get the difference I was experiencing. Wow and better wind drift too! I gotta get some more Bergers!
Double WTF! Shoot some more and am back on my charted dope again, all has turned to normal.
Got home and looking at my notes. 2 moa high. There has GOT to be a reason. Not just my lousy shooting either. It was consistent for a while. I check my gun, check my scope. All is well. I am thinking it was just that one box of ammo. Wondering if my scale might be off. Make a note to buy some checkweights.
So I am now reloading, removing primers and prepping my brass that I shot that day. I get to one box and the brass feels a bit different. I notice it is Lapua brass (I don't mix my brass I keep it in a case of 20). I had bought some factory ammo that used lapua brass. All my other brass is Hornady. Hmm, I say, must be it. Lapua brass can cause 2 moa of elevation change! I gotta get some more of this stuff!!! Then I look at the label I put on plastic box. I used different bullets also! I remember now! I loaded 155 Bergers instead of 155 Lapua Scenars. So that is it! Going to put any non-standard loads into different colored ammo boxes from now on!
I just got finished working with JPM ballistics and making the BC .6 instead of .5, adding 70 fps (Lapua brass is thicker, less case capacity so more pressure) to my Lapua Scenar ballistics table. I get the difference I was experiencing. Wow and better wind drift too! I gotta get some more Bergers!
