10mm Conversion Lab - C'mon in Y'all

[Doug M.]

Who did you send your CS40 to? I hit a big snag getting my conversion finished when my local smith refused to modify the barrel. Said the CS would be a .41 Magnum snubby and would blow up.

*
BMCM is the one referred to. PM him for his business address - he is now formally a gunsmith with FFL and all that jazz.

As for the question about his well-being: Other than the "joy" of working on my recovered stolen revolver after 7+ years out of my possession, he seemed fine a couple days ago.

 

[BMCM]

my local smith refused to modify the barrel. Said the CS would be a .41 Magnum snubby and would blow up.

That's crazy talk... I've yet to have one of those blow up in my hand with the hottest ammo I can get, usually Underwood & WW 175gr Silvertips. I personally test drive before sending them home to make damn sure they work right. A CS40 barrel is of the exact same chamber cross section as any of the 10xx guns and 10mm Auto essentially runs at about the same SAAMI Max pressure as 40S&W ... 37.5k vs 35k. That barrel is exactly the same as a 1006 tube, just two inches shorter with a tad shallower chamber.

Cheers
Bill

 

[cherrypointmarine]

I can attest to the fact Bill test fires them . I even got the target , with notes as to the distance and ammo used . You couldn't ask for a better gunsmith . I would trust him before I sent something back to you know who .

 

[BMCM]

Ahoy there Shipmates...

By now I've completed a goodly number of these conversion projects and it occurs to me there are a few things I have refined that perhaps I could share.

Here we're going to focus on the magazine followers.

Looking back, I find the precess I was using to midify the 10xx white followers to work in the single stack .40 mags kinda crude. The setup was tedious for every single piece and the amount of material removed was simply based on measurements of the orange .40 follower.

What I wanted to do is make the setup fast & simple and remove only the absolute minimum amount of material from the new follower in order to best preserve the strength & longevity of the part.

So, here's what we did...

Machined a mandrel of sorts from a block of delrin that when inserted into a follower and clamped in the vise, holds the follower perfectly level at a repeatable height in relation to the cutter.

Clamped in the vise. Now I'm using a 1/8" carbide ball end cutter. On the first part I zero the "Z" axis on top of the follower then lower "Z" 0.125". From this point I don't have to adjust the cutter height again for as many followers as I need to machine.

Spin up the tool then advance the cutter into the work 0.012" and cut the left side.

Then without changing anything else. Loosen the vise, flip the part around and cut the other side.

Rinse & repeat for as many followers as needed then we change the cutter to this 15° taper mill.

Then we process all those followers with the taper cutter in the same fashion. Once the first cut is dialed in it's zip & flip & zip again, stick the next follower in the vise & repeat. We're adding a 15° bevel to the top of the follower on both side 0.060 wide or about 1/16".

Flip the part and cut the right side bevel.

Unmodified white follower in the foreground with a orange 40 and a modified white follower behind for comparison.

Repeatable for as many as I need, perfect every time and each precisely identical.

Meshes with the feedlip contour in a single stack 40 mag pretty nicely If'n I do say so myself

So, anyone know of someone handy with 3D modeling and perhaps with a 3D printer? Would be handy to have a backup plan for when the supply of 10xx white followers dries up. Not just for these conversion guns but for all the 10xx guns as well. Followers are a wear item ya know.

That's all for now, Happy Ten Millimetering

Cheers
Bill