Bench rest setup

[joeb33050]

We've been talking at the range about movement of the group center as the shooter moves from location to location on the target. If the gun is zeroed at, say, the top left bullseye on a 2' square paper, and the shooter moves around the paper from bullseye to bullseye, they see/he sees the group center move. Or so they say. I don't see this, but I shoot with a muzzle clamp/anti-cant device a lot of the time. My bench rest is a Hoppe's with a bag double-sided-taped to it. The bagholder gizmo is free to turn on the screw, the round nut is loosened and the screw turned to raise and lower the rest, then the round nut is tightened. I don't know if somebody taught me to do this or what.
I kind of thought the two guys who asked/talked most about the moving centers were new or inexperienced or something, but they both-and others who mentioned the problem-shoot some small jacketed bullet groups.
Today I noticed that one of the rests didn't have a movable top, the top didn't swivel. A gray palstic but substantial rest. I looked at the other, didn't get into it, but that one wasn't free to swivel but would swivel.
Is it the swiveling top that keeps my groups in the same relative position, or am I nuts? Or both?
Do you have your top bag holder thing free to swivel?
Do your group centers move as you move the point of aim around the paper?
joe brennan

[mainiac]

In i.b.s. score shooting, we shoot a target that is about 14x24 inches,with 6 bulls. Fire one shot at each,(you end up going all the way around the paper) the ten ring is half inch,and the x is a dot one-sixteenth inch. A good shooting gun will punch 20-23 x,s on average. Needless to say, theres no point-of impact shift between bulls. But, on a factory gun with barrell NOT floated.... all bets are off!

[jhalcott]

the problem may be scope parralax. When you have parralax ,if you move your eye from the center of the scope ,the reticle may move a bit. Or at least it seems to.

[Hunter]

With my target rifle shooting several targets located in different areas at the impact berm point of aim and point of impact remains the same. If you are getting parallax problems a quality target scope will have parallax adjustment on the objective lens. Inconsistent position building may be some of the cause if you have point of aim point of shift during position change.

[Murphy]

Proper bench technique is the main focus.

Many things can influence how a gun will group. Some people can only ring a 2 inch group out of their favorite rifle and never realize why it won't do any better.

Sometimes it is the gun and load combination, many times it is the shooter.

Long ago I read the book: The Accurate Rifle, by Warren Page.

I was amazed at what I learned from that one book. Even down to how much pressure your cheek is applying to the stock can make a difference in shooting groups.

This book is still available if you do an online search for it.

Murphy

[ARKANSAS PACKRAT]

Murphy has it right, the little things will make you think you're snake bit. I have a heavy 22-250 that's scary accurate, I could make it shoot cloverleaf groups at 100yd by moving my thumb on the stock, pistol grip,and by grip pressure. If everything is correct, then a rifle will teach you what to do to make it work.