Do you have experience cutting a breech block hole that you would like to share?

What is a breech block hole?

The 'square', vertical, hole that the breechblock follows on a single shot, falling block rifle. In the upper position, it is behind the cartridge when it is fired. In the lower position it allows the cartridge to be extracted and the rifle reloaded.

I would guess that a drill is first used to hog out the majority of metal. Then a broach is employed to cut the "keyways" for the breech block. That's one way.

quote:

Originally posted by gwahir:
Do you have experience cutting a breech block hole that you would like to share?

Wire EDM. Will save you a ton of issues down the road. Make it happen. There are plenty of shops out there with EDM.
For that matter, get as much of it wired as possible. The hole, top and side profiles, leaving only a few milling operations.

Wire Edm is very accurate and can be done even after the material is hardened. I have used it a lot on production parts. That was in a former life time!

I had one wire EDM'd. One with a 5 degree angle on the back face.

The guy buggered it up, so I built a jig to guide a file on roller bearings.
Wasn't great for the file but it got the receiver fixed.

Now my brother (who is a custom knifemaker) has shown me commercially-available filing jigs which have thin carbide "wear pads" for the file to register against.

If wire EDM was not an option, the next best would probably be a shaper with file finishing. I have also seen and done broaching with a milling machine (spindle locked, using just the ram). If really pressed, one could even resort to filing after rough drilling. But it's going to be a labor of love doing it that way.

Wire EDM (assuming the operator knows his business) is certainly the fastest and easiest way.

a shaper is the next best solution - which kinda stinks that most people have never heard of one, and fewer used one

Holes are, by definition, round. You might want to cut a slot. I have a few Sharps, and none of them have holes for the breech block. And I was in tanks for many years, all use vertical dropping block breeches, just like a Sharps, none with holes. Maybe holes for the firing pin.

Actually, every child knows that they cannot put a square peg in a round hole. They have to use a square hole!

Most gunsmiths and gunmakers would call it a breech block mortise...


Take a look at Ruger # 1's method for a "square hole" for an easier way to skin a cat.

quote:

Originally posted by dpcd:
Holes are, by definition, round.

"I did not know that." (As Walter Sobchak would say )

AKA "A bad place to be".. HAR!