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BAJ
09-22-2011, 10:44 PM
I have been testing some ammo indoors in a new rifle and I am getting considerable horizontal dispersion in my groups. What are some common causes of horizontal dispersion, when there is no wind?

Brian

edgerat
09-22-2011, 11:01 PM
I don't know much about this game but, does it do it with different ammo? When I see horizontal on my gun it is usually ammo that is wind sensitive.

Pepper1079
09-23-2011, 07:42 AM
or tuning

Charles E
09-24-2011, 02:36 PM
I have been testing some ammo indoors in a new rifle and I am getting considerable horizontal dispersion in my groups. What are some common causes of horizontal dispersion, when there is no wind?Ah, as with most "what could it be" questions in benchrest, it could be almost anything. First of all, while there is no wind indoors, there can be air movement. That means there can be mirage -- enough to take you from one side of clipping the x to the other, without noticing, unless you pay close attention. But you probably mean more dispersion than this.

It could be the scope. But if it shoots well with other ammo, that's unlikely.

The most obvious culprit is gun/bag handling. This morning, before the match, I was shooting groups while adjusting an old Henrick device. At 5 and 6 inches in front of the forearm, I shot 4 five-shot groups where every shot stayed completely in the white of the 10 ring (the big IBS target). But when I shot a card, having to move the rifle for each bull, the dispersion was much greater -- enough so that one of the 10s on the IBS target would have been a nine on the IR 50-50 target. Since I shoot free recoil, obviously something in my bag setup/rest movement was throwing shots.

It could also be tuning. Barrels don't vibrate only in the vertical plane. The vibration pattern is more like an oval, or infinity symbol -- greater in the vertical plane, but still there in the horizontal. You *might* be able to tune it out.

Or a combination of all the above. And here's one from column B: If other ammo shoots well for you, the obvious thing is to not use the ammunition that has horizontal dispersion, whatever the cause.