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Posted: 5/20/2009 10:33:41 PM EDT
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I'm new to scopes and I zeroed my PTR 91's scope(Burris 3x9) at my indoor 25 yard range. I had 3 shots going through the 1st shots hole dead center on the target. Today I took it out side and shot it at 100 yards to see where I was hitting. I was under impression that a zero at 25 yards will be a little high at 100 yards and a little low at 200 yards.
Well my 1st group(3 inches total) was 5 inches to the left and 9 inches high! Why would my windage be off when it was right on at 25 yards at the indoor range and why so high? No wind at all. I clicked it back centered and brought it way down to about 2 inches high. Fired it at 250 yards and was about 6 or so inches low. At 250 yards a clay pigeon was very hard to see even with the scope on 9. Maybe I should have got a 14 power. How far are you PTR owners shooting out to? What size groups are you getting at 100 yards? Thanks for any input! |
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You overlook the effect atmospheric conditions have on ammo, the bullet & the scope's parallax, IMO. Humidity & temp both have effects on bullets. What you listed isn't surprising to me, in fact, it would be surprising if you had NOT had changes from the indoor to the outdoor range.
There's also the other possibilities on the scope, such as it getting bumped, not properly seated/tightened, etc. I'm not saying this is what happened, just that it's a possibility. Speaking as one whom has learned the HARD way, always sight your scope in with the same exact conditions as when you're going to be shooting the most ammo or the most difficult shot. Despite them being quality scopes, it's not unheard of for my scopes to be off 2" from range visit to range visit. My .o2 |
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Quoted:
So if they sit in the safe for a few years do scoped need to be dialed back in or do they stay close to where they were zeroed? Speaking only for my scopes, they all needed to be adjusted some. Shooting different lots of ammo from 2-3 years ago to the present day lots also will cause a variation in the zero as well. It won't be quite like buying a new scope & sighting it in, but it will most likely need some twists of the dials to get back to zero. Forgive me if you already know this, but different brands of ammo will also cause the zero to be different. |
Ring heigth above bore centerline will determin the diff in trajectory, I'm not at all surprised in the vertical diff, however the diff in windage would puzzle me unless you were useing diff ammunition.  Left or right hand twist can/will have an effect as distance increases but shouldn't have much effect at 100 yds.
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