eltorro said:
These are the exact questions I'd ask too.
I don't know much about doubles so please keep the info coming.
Why would a lighter bullet shoot wider? Are they regulated to shoot POA @100 or just keep the bbl center-diam distance as two parallel trajectories?
Shed some light for the noobs.
Hey, I don't even know what I am talking about
I am just flying by the seat of my pants here. Anything I am saying could be wrong, or totaly opposite of the truth.
The thing that I do know for sure about doubles is that there is no hard fast rules about regulation. Sometimes the gun reacts totaly different than expected.
If you could get thes guns to regulate at 100 yards with any ammo you would be doing good. I would be happy with a 4" four shot group (right, left right, left bbl) at 100.
I think how the gun shoots is all dependent on recoil timming. The things that affect regulation are, bullet weight, bullet shape, velocity, type of powder& pressure generated, how you hold the rifle, if there is a scope on the rifle and mabey even if the shooter is left or right handed.
I know that you cannot shoot the rifle off the bench and expect it to allways regulate the same as standing free hand. This is just because of how the gun moves as you fire it. A regular rifle has the bbl in a straigt line with the stock and your sholder. The recoil causes it to move up and back. With a sxs double the bbls are to the side of the center of the stock. Under recoil the gun moves up, back and to the side. The right bbl will push to the right the left to the left. This sideways movement will affect the flight of the bullet in relation to where the muzzle jumps as the bullet leaves the end of the bbl. No doubt a heavy recoiling rifle at low velocity will increase the problem (shoot farther to the left and right)
It is this action that causes a heavy bullet (more recoil slower velocity) to shoot wide. In contrast a light bullet (low recoil) will zip out of the bbl quicker (before the bbl moves to far due to recoil) and will not shoot as wide.
The bbs on a regular double (not the Baikal) are pointed together (cross eyed) to compensate for this and are set for a certain load (as in one brand of shells at one weight, like 180g winchester power points). Regulation can be done only in one way, by shooting it, taking the bbls apart, resetting them then trying them agiain. Lots of man hours of highly skilled labour. Very expensive. The Baikal has a jack screw that lets the owner push the bbls farther apart or let them ride closer together. One bbl will be fixed the other is the free floater that can be adjusted. This introduces another problem, one bbl is fixed the other can be set with varing pressure on it. As anyone who has played with forend pressure knows this can adversly affect the accuracy of the gun. A double can only be as accurate as it's worst bbl. If introducing a pressure point on the bbl causes bad vibrations that bbl could be shooting all over the place. Additionaly as the bbls heat up (remember 4 shot groups) the pressure on the jack screw can change. All of this is going on with one bbl, mean while the other is fixed (and is #### stiff from the rib running down between bbls) and can shoot entirely differently.
Add to all that the fact there is no adjustement for up and down. What if one bbl shoots 6" higher than the other at 50 yards? You will never get any better than a 6" group unless you can find a load that shoots better.
I have herd that when a double is fed ammo that is totoaly wrong you cannot get it to hit a 4x8 sheet of plywood at 100 yards. Hopefully things won't be that bad.
Take all this with a grain of salt as I don;t realy know what I am taking about .
