This is a kit to reduce the size of the late model apertures on the M1 Carbine. This is a legal modification for the CMP ‘as issued’ class. This modification has not been evaluated on the earlier style flip-apertures. It might work, but has not been tried.
You do not need to remove the aperture or sight from the rifle to reduce the aperture.
The kit includes a #45 drill bit, a #3-56 plug tap, a 0.050″ Allen wrench, a threaded set screw with a 0.042″ diameter hole, and Loctite.
Tools you will need:
- a tap wrench that is adaptable down to a #3-56 tap.
Steps for reducing the size of your M1 Carbine aperture:
- Use the #45 drill bit in the aperture hole to smooth out the hole to a consistent diameter. This should remove very little material as the USGI aperture is almost the exact size for the tap.
- Use the #3-56 plug tap (with your tap wrench) to tap screw threads into the aperture hole. Apply a few drops of oil to the tap before starting.
- Place a small drop of Loctite on the outside of the threaded set screw.
- Insert the threaded set screw, using the allen wrench, into the threaded hole in your aperture.