which raises another question, being a Cobra action (.5 in. shorter than most) is the pivot point always the distance in front of the action?
I don't think anyone knows, for sure.
I have experience with 10-15 rifles, five or so different front and rear bags, (and these not switched as pairs), 5 or so different rests/tops, and innumerable barrels. But I've never at down and thoroughly tested how a rifle "rides the bags", and don't know of anyone who has done so definitively. It would be a long & expensive study. As far as I know, all any of us have are "impressions" about what works.
I'll tell one story. I had a Kelbly-built rifle with the built in weight system. That is, an LV rifle with about a 2 pound weight you could add to the butt for shooting HV.
Now conventional wisdom says this isn't the way to go, all you get is a butt-heavy rifle. What I found was if I moved the rifle forward on the front rest -- pretty far -- the weight balance between front and rear was restored. Here is the kicker: it shot better in the "HV" configuration, where the front rest was closer to the action.
Aside from absolute position of the rests, sandbags themselves add considerable variables to how a rifle groups. There probably is an ideal, but I know of no one who has tested all the possibilities -- fill, position, sand edge, and on & on.
The same applies to barrel stiffness. Is it stiffness per se we want, or mass? The two don't have to come together. And are we after "stiffness" when looking at the barrel as a single object, or does "location" matter - i.e., is stiff at the muzzle more important?
For example, if you use a straight 5 inches of 1.25 at the rear of a barrel, then use a Hunter taper to the muzzle, that barrel will be stiffer than a barrel of the same weight using a typical LV profile.
But a number of people have accepted a loss of stiffness of the whole barrel to put a tuner on the muzzle, and they shoot fine. They even shoot fine outside the "tunability the tuner imparts, perhaps in part because the extra mass at the muzzle cuts down on muzzle movement.
There are also the tubed/tensioned barrel rifles I and others have used. With 1,000 yard Heavy Guns, we seem to be up to the point where we can write a cookbook on making an accurate rifle. But the machining costs are considerable if you don't do your own work, and the "recipe" only works for rifles weighing 50 pounds or more. The "lighter" versions have had mixed success, and we don't know why. Significant though is the barrels themselves in these rifles are quite light compared to conventional wisdom. Anyway, the point is "stiffness" probably isn't the simple notion it may seem at first.
Whatever you decide, good luck to you.
Charles
