Regulating a Drilling scope. - 09/21/13 05:22 AM
Twice I've seen examples where a Drilling scope is wound out to minimum vertical adjustment and yet it is still not where the shooter wants it to be. Where does one make the next adjustment?
For instance, a particular 1971 made Krieghoff Trumpf with a Krieghoff factory 3-claw, 2-piece mount and European mounted scope. Using Sellier & Bellot factory loads, 131g, it shoots 2" high. Using published a Vihtavuori N140 load for rimmed 6,5x57R and various 125-grain to 130-grain bullets, it shoots 3,1/2" to 6" high. There's simply no more adjustment left in the scope to regulate it any better than that. These loads chrony to the published spec, by the way.
The rifle barrel is very accurate, it's not a case of a damaged crown shooting away from point of aim either. It looks fine under magnification. The Drilling itself is in well maintained condition, not much used, (perhaps now we know why!)
The front mount is dovetailed into the rib and high enough it looks like it could be driven out and replaced without needing soldering. I'm guessing that one option would be to replace it with a slightly higher mount. But fitting it to the 2 claws of the old front mount would be a job for a skilled European gunsmith, surely. Not too many of them around here.
The other option that occurs to me would be to take a few thou off the leg of the rear scope mount, where this flat metal around the rear claw sits on the base-mount fitted to the barrel. This would tilt the scope upward somewhat and the barrel downward in a relative sense. Foolhardy or a simple cure? Please let me know.
The mounts are about 4" apart, so any removal of metal would have 900x the effect at 100 yards, so 1 thou removed would equal 900 thou change in POI.
Am I on the right track here or should I just give it a whack with a big hammer? What's the usual procedure?
BTW, the serial number is 71*** and looking at a 'Waffenpass', the small owner's booklet that came with a near-identical Drilling of this era, (serial 74***), Krieghoff used a 6-gram (c. 100 grain) 6,5x57R bullet to regulate the sights, so perhaps a change of bullets, powders and etc., might work. However I'd anticipate a lighter bullet only making matters worse.
Thanks in anticipation.
For instance, a particular 1971 made Krieghoff Trumpf with a Krieghoff factory 3-claw, 2-piece mount and European mounted scope. Using Sellier & Bellot factory loads, 131g, it shoots 2" high. Using published a Vihtavuori N140 load for rimmed 6,5x57R and various 125-grain to 130-grain bullets, it shoots 3,1/2" to 6" high. There's simply no more adjustment left in the scope to regulate it any better than that. These loads chrony to the published spec, by the way.
The rifle barrel is very accurate, it's not a case of a damaged crown shooting away from point of aim either. It looks fine under magnification. The Drilling itself is in well maintained condition, not much used, (perhaps now we know why!)
The front mount is dovetailed into the rib and high enough it looks like it could be driven out and replaced without needing soldering. I'm guessing that one option would be to replace it with a slightly higher mount. But fitting it to the 2 claws of the old front mount would be a job for a skilled European gunsmith, surely. Not too many of them around here.
The other option that occurs to me would be to take a few thou off the leg of the rear scope mount, where this flat metal around the rear claw sits on the base-mount fitted to the barrel. This would tilt the scope upward somewhat and the barrel downward in a relative sense. Foolhardy or a simple cure? Please let me know.
The mounts are about 4" apart, so any removal of metal would have 900x the effect at 100 yards, so 1 thou removed would equal 900 thou change in POI.
Am I on the right track here or should I just give it a whack with a big hammer? What's the usual procedure?
BTW, the serial number is 71*** and looking at a 'Waffenpass', the small owner's booklet that came with a near-identical Drilling of this era, (serial 74***), Krieghoff used a 6-gram (c. 100 grain) 6,5x57R bullet to regulate the sights, so perhaps a change of bullets, powders and etc., might work. However I'd anticipate a lighter bullet only making matters worse.
Thanks in anticipation.