I'm using the M24/30 FN Mauser carbine rear sight but I'm going to shorten the sight leaf. I found out the hard way that it is hardened.
Anyway, after cleaning up pieces of broken end mills, I managed to use a Carbide end mill to mill the end and pivot slot of the sight leaf.
(67) Slot is already milled; milling end down.
(68) Shortened sight leaf on left; original sight assembly on right for comparison.
(69) This is why I hate micro-machining. I can barely see what I'm doing
[which is milling .014" off each side of the pivot ears] and I can't get any feedback from the big heavy toolholder/vise/table feed. This is a 1/8" Carbide end mill.
(70) Another part I hate: Filing the square-cut ears round. My files are barely hard enough to cut the hardened sight leaf.
Lots of filing and fitting; I want it to work, but also minimize the gaps. This ain't no work for an old man.
Next I need to cut the FN carbine sight ramp down to match the shortened sight leaf. This is a complicated procedure, involving calculating the bullet weight & shape, the powder charge and powder composition, the barrel length and rifling twist, bullet drop in meters, the curvature of the earth, local variations in gravity, Pythagorean theorem, Sine, Cosine, Tangents...Ah, screw it. I'm just going to make a flattened ramp.
(71) Milling down the back of the ramp to match the height of the barrel extension.
(72) The FN Mauser spring is way too strong for my taste; it's ~1/4" wide x .040" thick...so I dip into Brownell's flat spring assortment, the thinnest is .030", so I'll use that.
(73) The Brownell's flat spring stock is .500" wide, so I mill it down to ~.025". I clamped it to a piece of scrap aluminum.
(74) Finished spring shown next to FN Mauser spring. Next is to harden it.
I have other things going on at the same time as I work on this; some use different jigs/fixtures/vises, so I'll be jumping around on the machining...
I'm going to mill the front sight base down and cut the dovetail. I've clamped the barrel assembly between plywood boards to get a 'soft' clamp, and use a reinforcing rod in the bore just to be safe.
(75) Barrel/sight base is leveled and squared; ready to cut down.
(76) Sight base has been shortened/milled ~.250".
(77) 1/8" x .100" slot milled in center for dovetail.
(78) 40º dovetail cut into sight base, .100" deep. It is .197" wide at base.
I'll be making a sight blade for it next. I'm debating making it out of Delrin or steel...I may do both. The Delrin is quicker to make and can be slightly wider in the dovetail since it has some elasticity, which would make it easier to adjust and also stay fixed in position...
I've sawn a blank out of a piece of scrap steel. This will be the front sight blade.
(79) Milling the bottom of the steel blank.
(80) Milling the 40º dovetail.
(81) Sight blank has been pressed into the dovetail in the barrel. Now I am milling the sides flat and level with the front sight base.
(82) All four sides milled flat and level. I hate machining anything this fragile.
One mistake trashes hours/days of work.
(83) Milling the sides of the sight to form a blade .120" wide. Using a radius end mill.
(84) Milling the sight blade at an angle to mimic the Finnish front sight blades used on Finnish Lugers and Lahtis.
(85) Mockup of barrel assembly and unfinished forearm. It looks odd.
