to stand wear, and to prevent the cocking piece by any chance slipping by the sear and firing the arm while the bolt is being closed. So the sear must engage the surface of the cocking piece notch for about 1/B inch at least, for safety; and obviously, this means a painfully long drag in the trigger pull.

Now study Figure 170, which is a Springfield trigger and sear, and is typical of all bolt action trigger mechanisms. Here we have a lever of the second class, the weight being located between the fulcrum and the power. The two projections "a" and "b" form two fulcrums. When the trigger is first squeezed, that is, on the preliminary pull or "take-up" fulcrum "a" bears against the under

side of receiver and draws the scar downward. The position of fulcrum "a" near the trigger pivot provides considerable leverage, so that only about a pound pressure is required on this take-up. until fulcrum "b" strikes the bottom of receiver when fulcrum "a" becomes inoperative. This change in the position of the fulcrum increases the pressure necessary for the final pull, to release the cocking piece.

The first operation in reducing the trigger pull is to carefully polish the contact surfaces of sear point and cocking piece notch where they come together on line A—B in Figure 169. Get these as smooth as possible with the slip-hone, but do not change their angles nor round their faces. Leave them both square, sharp and flat. The upper point of the sear may be found somewhat rounded, and this should be brought to nearly a sharp edge by carefully polishing ofi the surface C—D in Figure 169, using a fine grained carborundum stone. Hold the sear flat and rub it on the stone, but take ofi no more metal than is absolutely nccessary to sharpen the point, and do not bevel this surface. Finish by polishing with the hard Arkansas slip-hone. Now assemble and try the mechanism. You will probably find the trigger pull somewhat reduced, and much smoother in its action, but with considerable creep still remaining. Most gunsmiths remove this creep by grinding off more of the upper surface of sear on line C—D, Figure 169, and if you do it this way you must exercise extreme care lest the cocking piece be released before the

Was this article helpful?

0 0

Post a comment