DUGABOY1
(.400 member)
18/06/06 04:45 AM
Re: are express rifles accurate?


In reply to:

Dugaboy, I always thought that the barrels were supposed to shoot to the same point? But, parallel bores make more sense from a design standpoint.







333Jefery The bores are not paralell, but converge! This is where many get the idea that the bullets must cross paths! The barrels must be made to converge, because of what is called barrel time, and recoil arch. Simply, the RIGHT barrel will have a line of sight through the bore that points to a spot that is low, and to the LEFT of where the sights are pointing on the target, and vice- versa for the left barrel. IOW, they not only converge, but point low as well. The amount is decided by the man regulating the rifle by fireing it at the target, and with wedges soldering, and resoldering till the proper barrel convergence is met.

The barrle's line of sight through the bore does cross, the bullets do not! The reason the bullets do not cross, if properly loaded, is, when the sights are on your point of aim, and the trigger is pulled, the recoil arch starts. For the RIGHT barrel it recoils up, and too the RIGHT with the bullet traveling down the bore. The point where the bullet leaves the muzzle should be where the sights were pointing when the trigger was pulled, but slightly to the right of poa. and vice versa for the left barrel.

Take a square piece of paper, and draw a line from the top corners accross the paper to the opposite corner on the bottom of the paper. The point where these two lines cross is point of aim. The bottom LEFT corner is where the RIGHT barrel is pointing with the sights pointing at the apex of the two lines in the middle. As the rifle is fired the right barrel more or less follows the line up along that line till the bullet exits. Where it exits, determins where it hits the target. The slower the bullet travels, the higher, and farther to the right it will strike the target, and vise versa for the LEFT . The key is to have the bullet exit just at the point where it will strike a place just on the right of point of aim, for the right barrel, and the on the left for the left barrel. This means the center of each barrel's individual group, should be on it's own side of POA with a composit group for both barrels forming a group that the center of will be at the poa.

This convergence cannot be pre- programed into the rifle,even identical rifles of the same chambering, but must be done by trial and error! When the load is proper the bullets from one barrel doesn't cross the path of the other barrel in flight!



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