I am having a MOA drop mystery with my 338 rum that I cannot figure out. I am shooting 1 to 1.5 MOA high at longer ranges then I should be. At first I thought it could be scope related but the scope checks out with tracking and holding zero. I took the rifle off the bench and sighted it in at in 3.1 inch’s high at 100 yards with 250gr Nosler Accubonds. The last time I chronograph these I had two shots dup 2995fps and the third was 3000fps 12ft from the muzzle so I figured 3000fps in the ballistics calc. Anyway I went to shoot it at 300 yards off the bipod and I was 3inch’s high when it should be a little more than 1 inch low. I then fired my 300gr Berger Hybrids which are 1.5 inch’s high at 100 yards and they were only 4 inch’s low at 300 yards? The velocity on those is 2640fps. They should be 9 inch’s low at 300 yards. Now I know why I have had to take a MOA or more off at 600 yards for each bullet but I do not know what is causing it? My best guess would be recoil? Some guns will shoot a little high with a bipod that is why I zero my rifles shooting off the bipod but I have never ran into this. Your thoughts?
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Range Report MOA drop mystery?
- Thread starter dakor
- Start date
Re: MOA drop mystery?
Did you get the scope height correct?
What kind of atmospheric data did you put in there?
What chrono are you using?
How does the data look at distances in excess of 600yd (if possible).
Did you get the scope height correct?
What kind of atmospheric data did you put in there?
What chrono are you using?
How does the data look at distances in excess of 600yd (if possible).
Re: MOA drop mystery?
When did you sight it in @ 100 as compared to when you shot it at 300, same day, or stretch of time. If its the later, then it could be temp change. If it is the same day, they might be running faster, or is this your first time shooting it at 300 and are you just getting your info from a program?
When did you sight it in @ 100 as compared to when you shot it at 300, same day, or stretch of time. If its the later, then it could be temp change. If it is the same day, they might be running faster, or is this your first time shooting it at 300 and are you just getting your info from a program?
Re: MOA drop mystery?
Scope height is 1.7 and I sighted it in at 100 yards the night before and shot early the next morning so the temp was within a degree or two. Not my first time shooting at 300 I have shot at the distance and beyond a lot. I was trying to figure out why I always had to take 1 to 1.5 moa off of the dope from what the ballistics Calculator told me at 600 yards every time I shot it at that range over multiple days of shooting. I moved back to 100 to make sure the rifle was still at 3.1 inch's high then tested at 300 and I was shocked. I shot my 375 H&H at 300 the same morning and that was right where it should be about 7inch's low with my 250 yard zero. The 338 rum weighs about 11lbs ready to go with no brake so I am wondering if it is muzzle jump causing the height difference? I use mostly big game ballistics Calculator and also have used JBM trying to figure this out and I cannot come up with anything.
Scope height is 1.7 and I sighted it in at 100 yards the night before and shot early the next morning so the temp was within a degree or two. Not my first time shooting at 300 I have shot at the distance and beyond a lot. I was trying to figure out why I always had to take 1 to 1.5 moa off of the dope from what the ballistics Calculator told me at 600 yards every time I shot it at that range over multiple days of shooting. I moved back to 100 to make sure the rifle was still at 3.1 inch's high then tested at 300 and I was shocked. I shot my 375 H&H at 300 the same morning and that was right where it should be about 7inch's low with my 250 yard zero. The 338 rum weighs about 11lbs ready to go with no brake so I am wondering if it is muzzle jump causing the height difference? I use mostly big game ballistics Calculator and also have used JBM trying to figure this out and I cannot come up with anything.
Re: MOA drop mystery?
That is some good reading thank you. I should clear something up this was the first time I shot this rifle at 300 yards to confirm it's zero. When I sighted the load in I sighted it for 3.1 inch's high at 100 yards then went straight out to 600 yards and started playing around with it there. That is still weird I am seeing that flat of trajectory but I guess I should not bitch.
That is some good reading thank you. I should clear something up this was the first time I shot this rifle at 300 yards to confirm it's zero. When I sighted the load in I sighted it for 3.1 inch's high at 100 yards then went straight out to 600 yards and started playing around with it there. That is still weird I am seeing that flat of trajectory but I guess I should not bitch.
