Setting a scope

[mhulley]

Hi Guys, Just a quick question. If my rifle is shooting in the bull at 25m will it shoot in the bull at 100m?

[Lian]

bullets drop, have a trajectory.
google "ballistics" for your calibre&speed for a rough estimate/guideline.

[Bundu Ric]

Search the internet for a program called "Remington Shoot" which is a nice little tool showing tracjectory for most calibers and bullet weights, as well as for example if you want your rifle zerod at 200 m then zeroing at 23 m will work as well.

[driepootx]

No, the fallacy of setting at 25m needs not to be perpetuated. Shooting at 100m gives you a much better perspective and can usefully be extended up to 300m. Remember that errors at 25m are enlarged by 4x at 100m. Dont even think of 300m. Get your rifle on target and then check at the longer ranges. A setting of +50mm at 100m will enable you to succesfully shoot to 300m. Again check the trajectory at the mid and max ranges.

[Dick]

mhulley;183668]Hi Guys, Just a quick question. If my rifle is shooting in the bull at 25m will it shoot in the bull at 100m?

No, it will (or should) shoot high. 25m is too short to sight in a scope. A scope can be set roughly to point of aim in the workshop, but not close enough for use. The purpose of workshop setting is just to ensure that it will hit a target. But it can't be set close enough to guarantee a hit 100m. That's the purpose of shooting at a 25m target, to at least guarantee a hit, and adjust point of impact at 25m, to guarantee a hit at 100m, at which range the scope can be zeroed exactly.

100m Tends to be regarded as a sort of standard because many of us don't have access to a longer range. But 100m is a short zero for a hunting rifle, unless it is to be used at not more than 150m. Trajectory is flat enough to be considered totally flat for that distance. But not for longer ranges, and a lot of hunting is done at longer ranges.

A rifle in the 30-06 class zeroed at 100m will print 150mm low at 200m and 500mm low at 300m. If you don't know what the drop is, you can't estimate the hold over, but even if you do, there is the possibility of significant error. If you factor in errors of range estimation, a rifle that might not group better than 2 or 3 MOA, wind, shooter fatigue and lack of an improvised dead rest, the risk of wounding is high.

It can be minimised by zeroing at longer range. If you zero at 250m, hold under at 200m and hold over at 300 will be about 150mm each. That a lot easier to estimate in the field than 500mm, and makes a clean kill much more likely between 200 and 300m.

Even better is to zero the scope on the point blank principle, which is a refinement of the above. But the full story is too long to post here. If you want to explore it further, e mail me privately boothroyd@polka.co.za

[mtoich]

No, the fallacy of setting at 25m needs not to be perpetuated. Shooting at 100m gives you a much better perspective and can usefully be extended up to 300m. Remember that errors at 25m are enlarged by 4x at 100m. Dont even think of 300m. Get your rifle on target and then check at the longer ranges. A setting of +50mm at 100m will enable you to succesfully shoot to 300m. Again check the trajectory at the mid and max ranges.

That's the short and simple of what you need to know.

If you have further questions I would reccomend that you take Dick up on his offer and e-mail him.

He's got wise words!

[barneyboy]

In my limited experience ,which has mostly been with .243's,I have found that by sighting at 25 meters, I was able to get a point of impact at minimal cost of ammunition . From there , at 100 meters, I was able to tighten my groups, and to set the point of impact for which I wished to shoot, and as others have mentioned, this is where a good set of ballistic tables will come in handy , as each caliber is particular to its own character.
Cheers,
Barneyboy