Rail / Sear slot design

[Flatliner333]

What is the reasoning for the sear slot in the rail being offset (____^____ ) instead of straight down both sides of the sear? Would it hurt anything if it werent offset ?

[cougar20th]

My belief coming from a design background is it is due to machinine. It is easier & cheaper to walk a larger bit back & forth in that pattern then it would be to use a smaller more fragile bit. It also has the side affect of creating less surface for friction with the sear.

Does it need to be that way. I would say now.

[renie]

cougar is correct in respect of maching you can use a larger diameter mill bit to creat the narrow slot. also machines faster :)
it is possible to use a smaller mill bit and do a straight slot but there would be more friction.

you only really need it thin where the sear sits on the pin and a point around the middle of sear front to stop it from moving too much.

[athomas]

The slot is milled wider than the sear to reduce friction, especially when there is gunk accumulated inside the rail and on the sear. There are two contact points on one side of the rail to the front and back of the pin, and two on the other side of the rail near the front and rear of the sear. These four points of contact help keep the sear from getting twisted and putting extra stress on the axel pin.

By using a larger mill bit, they can do the slot milling on only one pass.