It's done, and finally got to the range today for the first shots with my 10mm converted CS40 today. All I can say is "Wow!" What a great little shooter. Recoil was easily manageable but I didn't use full power ammo. I started off with Armscor 180gr FMJ, which is fairly tame, then moved up to the PMC 170gr JHP. The PMC was obviously more potent, but short of the power of, say, Underwood 10mm ammo. I didn't take any Underwood to the range today, but the next time out I'm going to give it a try.

The conversion was simple. I sent the barrel off to be reamed and headspaced for 10mm, and I gutted a couple of the CS40 magazines to accommodate the 10mm length. I used followers from the S&W 1076, but had to cut the sides down a bit to clear the 'humps' near the top of the CS40 mags.

I had already performed a trigger job on it to minimize the SA takeup. The recoil spring I used was from Wilson Combat. It's a 22# flat wire spring which is a little longer than the stock spring, but it fit well and still allowed the slide lock to function, so I didn't cut it down. The part # is 10SEN22, made for their 1911 Sentinel. Another company that makes flat wire recoil springs is ISMI, and you can use the 20# Sig 239 recoil spring. Part Number is GC26.

Here's the trigger video:

In summary, it's a great little gun to bump up to 10mm and feel confident that it will work. So far there has been no failures of any sort, and those rubber grips really make shooting a 10mm a non-painful event. Awesome.

If you plan to carry this 7+1 gun, which is very doable, you could replace the rubber grips with a thin plastic S&W grip from the 4013 and cut the bottom to fit. You'll need to use the mainspring pin and not the original grip screws to secure it. You'll also need to get the longer pin from those models, which use the mainspring pin, but you'll have to drill holes in the modified grip to accommodate the pin. Check with Numrich and others.

If you want to do this to your CS40, here's the info for the barrel work (it was $65 + $10 to ship). Turnaround was 2 weeks.
Van Schneider
The Gunworks
534 Scott St
Sandusky, Ohio 44870-3735

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Too cool! I like the idea of a compact 10mm that isn't a Glock or EAA.

And your handiwork is impressive.

Sweet, thanks for the info, pics and video. I want one now,Best of luck.

The CS40 magazines you show look different from the 4013 mags that have to have the welds drilled out to remove the spacer from the rear of the mag to accommodate 10mm rds. Are they?

.

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Waiting for the break of day

No, the magazines I have are the original 7-round CS40 mags. The tack welds are on the side of the body, with 4 on each side. They aren't all that obvious and I didn't have to drill them out. I just used some small side cutters and needle nose pliers to work the weld areas back and forth until they snapped off, then went in with a dremel stone to clean up the welds.

Here's a pic where you can see the spot welds.

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Don't forget to use a buffer.
Regards,
BM1

Recommendations? Something that doesn't get crushed too quickly. I'll probably want one before trying out the Underwood ammo. I'm pretty happy with the PMC hollow points, though, but want to compare them just because I can.

I'm still impressed how well it cycles, even slow cycling rounds by hand is so precise and smooth! This will be a keeper in the collection.

Hello Smokemup
Nice job! I think there is a CS 40 on GB. I was thinking about getting it but wasn't sure about finding the proper recoil spring. Now with your post I think I'll just start looking again. As an aside I am getting ready to convert my 4013 to 10mm after reading all the posts from Bad Man One. I've also been experimenting with my 4516 and 4013 by swapping the 4013 slide onto the 4516. It fits fine of course but I have no idea if it will function (just swapping parts guys, I haven't tried shooting it). I just thought it would be nice to have a totally stainless compact 10mm. I'm sure with the proper spring and buffer the alloy frame of the 4013 would be fine but I just had to check it. Anybody have any experience with that swap. I sure hope BM1 will get back in the game with some barrels, hint, hint! Now wouldn't it be nice to have a 4516 with a 10mm barrel! Any thoughts on that from all of you? Oh, the 4013 barrel is too short to fit in the 4516 slide and contact the bushing properly plus the barrel hood is narrower on the 4013. Anyway thanks for listening

This conversion has peaked my interest. How about converting a 4006tsw to shoot 10mm?

"I had already performed a trigger job on it to minimize the SA takeup. The recoil spring I used was from Wilson Combat. It's a 22# flat wire spring which is a little longer than the stock spring, but it fit well and still allowed the slide lock to function, so I didn't cut it down. The part # is 10SEN22, made for their 1911 Sentinel. Another company that makes flat wire recoil springs is ISMI, and you can use the 20# Sig 239 recoil spring. Part Number is GC26."

I'm currently trying the same Wilson Combat spring in my CS9 ( originally bought a couple wilson springs for 4513TSW, but then the Sprinco spring set came along ). Cut down the spring to 16+ coils like the original, and it feels right. I certainly wouldn't mind Wolff springs supporting more of our 3d gens, but at least there are a few alternatives to try.
Brent

Interesting. How does the alloy frame hold up?

About 10 or 15 years ago when Sig was importing Walther M2 in 40s&w some guys did the same thing.

The ones I have done have held up nicely.
Here are some tidbits of information;
CS-40 in 10 m.m. - DONE - CS-40/CS-45 Extended Magazines
Regards,
BM1

Any experience running 40 through a 10XX frame reliably, using a 40 conversion barrel or 4013 slide and barrel?

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USS ZELLARS
DD-777

1066 SSV, This barrel conversion thing is getting a little wild
Regards,
BM1

Don't think so. For one the 4013 is on the large (45, 10mm) frame. Even the 4013TSW isn't the same. It's on the medium frame, as is the 4006. Also the 4013 is a single stack, where the others are double stack, & has a spacer that can be removed to accomodate the 10mm's length.

Here's a comparision of the "beefier" 4013 barrel vs. a 4013TSW barrel.

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4013 vs 4013TSW barrel, breach view

(-01a)

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4013 vs 4013TSW barrel, muzzle view

(-02a)

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4013 vs 4013TSW barrel, top view

(-03a)

.

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Waiting for the break of day

Just picked up a CS40-10MM conversion off of gunbroker a couple of months ago. Have not shot it yet but the work looks good. Currently have it loaded with DRT 105gr. TMJ. My thoughts are the lighter weight bullet having less recoil on the small frame CS40.

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Big papa K

Which buffer and how is it installed?

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Marlin & Calico Specialist

Just snagged a CS40 a week ago, depending on how the
long-term works out for the 10mm's, might do it also...

So...its been a few months, how are things panning out so far??

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Marlin & Calico Specialist

Post bump!

I bought a like new CS40 tonight and after a Google search turned up this thread, well, looks like I may be in on the 10mm conversion soon!

How about a CS9 conversion to .357sig? Would that even be possible?

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USS Brewton FF1086
SWCA#3597

I highly doubt it.

CS9 conversion to 357Sig,possible.

Smith 3913 Chambered in .357 Sig (pics)

Wow!

I would of thought reaming a 9mm barrel out would be thinner than .090

Has anyone sucessfully converted the 5906 to .357 SIG? I know the breechface would need to be modified. I have an extra slide and barrel I was contemplating changing over to .357 sig caliber.

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Ret. LE, FA Instr, S&W Armorer

I bet the .357sig from a 4000 series would just be a barrel swap

Which buffer is used in the conversion? Part #?

When I did my 4053 conversion a couple of years ago, I couldn't find a suitable buffer. You may have to create one if you decide it is needed.

On my 4053, what eventually became the donor 10mm slide/bbl combination uses the "nested" recoil spring configuration....the smaller diameter recoil guide and a Wolffe 21 lb recoil spring (#47721) and a S&W OEM inner spring. (The original, unaltered .40 S&W caliber slide and barrel use the larger diameter recoil guide and a 21 lb Wolff spring)

Range testing confirmed this 10mm recoil spring combination as heavy enough to compensate for the added recoil, and still allow the slide to open completely enough for the slide stop to engage. I tried to tune the recoil springs so that the slide would reach the slide stop, but not come back far enough to impact the frame.

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Ret. LE, FA Instr, S&W Armorer

Wouldn't that mean that the slide is bottoming out on the springs then?

.

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Waiting for the break of day

In the 4053 (using the converted slide and bbl in 10mm), after trying several heavier outer springs with hardball practice ammo, the combination of the 21 pound Wolff recoil spring (#47721) and the OEM inner spring seems to give the proper resistance to allow the slide to reach the point where it will just lock back on the last round, but not impact the frame. There is still the approx. .0125" of travel available past the catch on the slide stop assembly with the springs installed, so I don't think the slide is bottoming out/damaging the springs.

Tactical Springs (tacticalsprings.com) also makes an inner/outer spring combination for the 4516-2 that will work in the gun.

Set up for factory Hornady "duty" or carry ammo requires changing over to a Wolff 23 pound outer spring, part# 47723. I believe these two Wolff recoil springs are actually for the 4513. It's a chore getting the slide to lock open with the heavier spring combination.

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Ret. LE, FA Instr, S&W Armorer

Hey...I just joined and found this thread. Very interesting, the idea of converting a CS40 into 10mm. I read all the posts and it seems like it's fairly straight-forward with little to no previous gunsmithing experience. I also immediately went on Gun Broker and started checking for CS40s. There are three on there right now, a blue with a buy it now of $675, a two tone with buy it now of $575, and a stainless that's at $579 with no bids, no reserve. What would be a fair price for one. Thanks and looks like a great forum community to be in.

I found mine on Armslist for $400, local. In Very Good Condition.
Almost feel bad for converting a good gun but then again, 10mm is the best mm!

Will this conversion only work with single stack 40’s? I found a 4046 locally I can get for a good price and would like to try this conversion, but don’t want to bother if the double stack mags won’t feed 10mm reliably.

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USS Brewton FF1086
SWCA#3597

The double stack 40xx pistols are built on 9MM sized frames. The 10MM Auto cartridge will not fit into the magazines of these firearms

The Single Stack 40xx pistols are built on the 45/10 frame so there are no issues for the 10MM Auto cartridge length in the magazines

Ok. I thought there might be a problem. Thanks for the quick answer. The quest continues...

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USS Brewton FF1086
SWCA#3597

I found a stainless CS40 on gunbroker and bought it. So I’ll be looking at doing this conversion in the near future. It’s my birthday present to myself

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USS Brewton FF1086
SWCA#3597

There are multiple reasons why you SHOULD get that pistol...
just not for 10mm use

.40S&W loaded to max or Buffalo Bore ammo is similar to downloaded
standard 10mm ammo...and being a double-stack holds enough
rounds to solve for zero a decent sized group of miscreants

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Marlin & Calico Specialist

Does anyone know if Van Schneider of The Gun Works mentioned in OP is still in business? I looked up his number and called him, but it’s been changed to an unknown number. Any suggestions on someone to do the chamber reaming?

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USS Brewton FF1086
SWCA#3597

I didn't even know that van was mentioned in this thread until today.
I know him but i haven't seen or spoken to him for a couple years, right about the time that he closed his shop which i was never in btw.

i have no contact info for him but would be interested to know if anyone knows if he's a member of this forum.

Google maps shows Gunworks at 534 Scott Street,Sandusky 44870 as permanently closed.
I bought my reamers from Midway and Brownells,both show currently 'out of stock'.
Stainless Steel barrels are difficult to machine and special cutting fluid needed.
And before you ask,no I will not chamber ream a barrel that isn't mine,too easy to screw up.
I used to see Gunworks set up at gun shows here in northern Ohio,if I see Van at a future show,I'll try to find out what's going on.

You might try on the 10mm-firearms.com forum if anyone does chamber reaming.

Please keep us posted with any updates! I have everything needed except the custom barrel work.

My Chief’s Special came in to the LGS on Friday and I picked it up yesterday. Tore it down and giving it a nice Kroil soak for a couple of days. I’ll post some pics of it when it’s back together. I was asking around at a couple gun smiths at the Local show this weekend and the general consensus was that chamber reaming is pretty straightforward. I found a source to rent the reamer and gauges for less than $50, so I would just need to rent the tools for the smith to use.

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USS Brewton FF1086
SWCA#3597

Actually, the barrel on mine is carbon steel. I checked it last night with a magnet when I was cleaning the Chief.

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USS Brewton FF1086
SWCA#3597

I believe the barrel in all the CS variants is stainless steel.

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Ret. LE, FA Instr, S&W Armorer

Not mine. It sticks to a magnet really well. Maybe the barrel was swapped out at some point? What other barrels are compatible with the CS40?

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USS Brewton FF1086
SWCA#3597

There are 2 basic types of stainless steel. We won't get into specialized alloys. 300 series and 400 series.
300 series-virtually non-magnetic,doesn't corrode at all,softer and machineable with specialty fluids.
400 series-contains less Chromium than 300 series,magnetic,will show signs of corrosion,harder and tougher than 300 series,more difficult to machine than 300 series.

Stainless Steel FAQs | Mid America Stainless

I did know that some SS was more magnetic than others, but I thought the alloys with less chromium in them were only slightly magnetic. Like not being able to pick up the full weight of the barrel with a magnet.

__________________
USS Brewton FF1086
SWCA#3597

Got the Chief all cleaned up. Did a quick photo shoot with it and big brother 1006 (my Christmas present to myself from forum member epj).

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USS Brewton FF1086
SWCA#3597

for reference

1006 38oz
4013 26oz 3.5"
CS40 24oz 3.0"

Question on gutting the magazine:
Is the follower the only thing you cut down on the sides? The hump at the bottom rear of my magazine keeps the 10mm follower from fitting. Does this get ground off? I do not see any weld spots on the inside of the magazine.
Any info is appreciated!

For those converting the 4013, 4053, I remember having issues with the crimps on the sides of the magazines that secure the spacer interfering with the follower. Had to take a pillar file and remove some material off of the protrusion from the inside of the mag body in order for the follower to work smoothly.

After removing the material, you may need to wrap the file with a very fine wet/dry paper or crocus cloth to polish the places where the protrusions were removed....basically just smoothing the rough crowns on the inside surface. The inside of the magazine should look as clean as possible, and be free of any defects.

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Ret. LE, FA Instr, S&W Armorer