A correctly jointed side by side double gun or rifle will show no gaps between the breech end of the barrels and the action face [standing breech] when closed and locked by the bolts. It should show some gap[.003-.006] between the barrel flats and the action bar. The width of the breech face and the hinge pin form a triangle which resists the side strain of firing the cartridge. For example, when the right barrel is fired, the strain is taken up by the left side of the breech and the hinge pin, and conversley for the left barrel. The opening strain is taken by the locking bolts.

As the hinge pin wears or the action is overstrained, the barrels come away from the action face. With some wear, and before a rifle is "off face" the barrels will stop against the standing breech at a slightly lower position, and the gap between the barrel flats and the action flats will diminish. This wear is compensated for by the slight taper built into the locking surfaces of the bolts and lumps. With more wear, the barrels eventually stop against the action flats, and the barrels are said to be "down on the flats". At this point,the rifle may still be tight, or some vertical loosness may be detected in the locking bolts.

With further wear or overstrain, the rifle will come "off the face", meaning that a gap occurs between the action face and the ends of the barrels. Once this happens, the rifle will loosen itself very rapidly as repeated firing will begin to hammer the hinge pin due to the head start given to the barrels by the loosness.

The best way to detect an "off face condition is to blacken the ends of the barrels with soot, and carefully put the gun together. Where the breech touches the barrels, the soot will rub off, and you will know contact has been made. This is the process by which the barrels were fitted to the action in the first place in the process known as "blacking down". A quick check can be done by holding the assembled gun to the light, and checking for no light showing at the ends of the barrels, and some light comming through the flats between the lumps. This does not work well with rifles that have sideclips or rib extensions. Another way is to close the rifle on a thin piece of paper. an "on face" rifle will not close completely. One can also remove the forend and while holding the stock and action, give the barrels a slow side to side shake. any looseness will be felt unless some clodpate has "tightened" the action by peaning the lumps. Be sure to check for this! Also examine the hook to be sure this hasn't been peaned as well.

All this being said, the only way to correctly repair an "off face" rifle is to either replace the hinge pin with a larger one and refit the barrels, or, for rifles that do not have replacable pins, weld the barrel hook and then refit the hook and barrels. Because the refitted barrels will stop at a higher spot on the standing breech, the locking bolts will also be tight again, and the rifle is good for a lot of further usefull life.

All the best, SXS