A few years ago I was searching for a replacement for an S&W 625 that I foolishly sold. I was looking for a 4” and stumbled across a good deal on a 5” instead. It was enough a bargain that I decided I’d “settle” and give it a go. Bought a Kramer horsehide pancake to match and quickly realized I’d found nirvana. For me the ultimate in sight radius, offhand holding, velocity gain over 3” or 4”, with a little more weight out front to help with recoil.
Fast forward to recently when I decided it was high time I get out in the shop and straighten up a little and get on some projects I’ve been putting off for way too long. Getting a couple things finished up and tinkering with my old tools made me realize I still enjoy working on some gun stuff and made me want to do something else.
So I did what any S&W guy in search of a project and perfection would do. I sourced a cheap 8 3/8” 629-4 that had languished for a while with no takers on a shelf in a gun shop and got to work.
The 8 3/8” will make up into a professional looking 5” job due to the placement of the roll marks, a 6” will look funny with the stamp out towards the muzzle after the trim.
I got some keystock and whittled out a ramp and blade.
It would be secured with a 6-48 screw, shot and trimmed for height with a preferred load, then removed, blued, and reinstalled with the screw plus some Loctite under it to hold everything down belt and suspenders style.
I’ve done them with the barrel on before but a factory type crown requires a trip to the lathe so I prefer to pull them. I machined a set of blocks out of aluminum, contoured to fit the barrel and underlug just ahead of the frame. Ordered a set of Power Custom frame inserts for my action wrench, they’re machined Delrin and very nicely made for less than $50.
Pulled the barrel and Rube Goldberged a system of V blocks and clamps to set it up in the mill. Using my antique Starret protractor level to assure that the top rib was level in both directions before using an indicator to pick up center. Once double and triple checked for level and center a 1/4” endmill was used to cut a pocket down the center of the rib. Light cuts with lubricant, this isn’t the most rigid setup on earth and there’s no need to rush.
Once the pocket was.040” depth and the ramp fit to my satisfaction I drilled my screw hole .100” deep and used a flat bottom bit to finish the hole for maximum thread engagement. A fresh 6-48 bottom tap with plenty of oil was gently worked down to the bottom of the hole followed by chamfering the lead of the thread with a countersink.
A quick trip through the lathe, using a tool ground to match the radius of the factory crown and the calibrated eyeball to replicate the factory job had everything looking skookum.
Then back into the vise blocks and the action wrench to be torqued back together and then off to the range.
Had to trim the blade once to get the height correct but it’s zeroed now with the rear elevation 1/3 up from the bottom with 250gr RCBS Keith bullets over 10gr of Power Pistol landing right on top of the front blade at 25 yards. Fits nicely in my Kramer I bought for the 625 to boot.