CS40 Conversion To 10MM

[JohnHL]

Pursuant to the 10mm conversion, yesterday I conducted a test which I hope may prove helpful.

I installed a 1006 top end on a 4516-1 frame.

I loaded the yellow follower, 4516-1 magazine with Remington 10mm, 180gr., FMJ and fired the mag load successfully.

Every round fed and fired and the slide locked open on the last round.
Completely normal.

I am now convinced that S&W 45 magazines will feed 10mm ammo and there is no justifiable need to modify the scarce 40s&w mags.

John

 

[Big Shrek]

Sure.

If tanks are made of aluminum.

John

Actually, they are now...take a look at an Abrams or a Stryker...Aluminium.

 

[JohnHL]

Actually, they are now...take a look at an Abrams or a Stryker...Aluminium.

Not the part that shoots!

John

 

[Big Shrek]

Not the part that shoots!

John

Same as the CS series, aluminium frames & armour, with a steel barrel

 

[JohnHL]

OK, Big Shrek.

I concede.

An Abrams tank can handle a steady diet of 10mm.

I'm still not so sure about a CS40.

But the 1016 (4013/4 slide and barrel on a 4516 frame) sure could.

John

 

[tlawler]

Anybody have any updates on their conversions? I am waiting on a gentleman who is a gunsmith and machinist to help me out once he takes care of a few things. I guess I'm a little bit chicken to make a first go of it on such an expensive firearm. I did pick up a rather inexpensive Mauser M2 to "practice" on. Midway had the finish reamer in stock, but the go/no go gauges are back ordered or otherwise not available anywhere. If I'm VERY careful, can I just use a factory 10mm round with the proper OAL as a guide? I'll ream just a tiny bit at a time and check frequently. One plus I see on the Mauser barrel is the "40 S&W" is small and not deeply struck, so it should be easy to have milled off. I was thinking of looking for someone to laser etch 10mm on the barrel when I'm finished.

 

[tlawler]

Got started on it.

Cleaned off the work bench a bit and got right to it. First, I drove the spacer out of the magazine without any problem. I still need to deal with the dimples that held it in, but the 10mm loads right in. The metal of the barrel cut easier than I imagined, and I've been taking it in approximately .05" increments. I've been using my 1006 chamber as a reference and I've still got a little way to go. I wanted to see if anyone will weigh in with some advice. On the 1006, the depth of the chamber is exactly 1.000" from the headspace shoulder(correct terminology?) to the edge of the hood. With a round chambered, the rim is .002" above the edge of the hood. Am I looking for the same distance above the hood of the M2 barrel? Right now, I'm .096" above it and just want to make sure I don't go too far.

 

[armorer951]

The minimum recommended chamber depth on the 10mm is .992". The problem with using a 10mm casing to measure the depth is there are many variations among available ammunition, so the measurements may not be correct, or exactly to spec. It would be better (safer) to use the actual gauge set (go, no-go) so that you are sure to get the proper depth.
I don't see any evidence cutting oil in your photos of the barrel in the vise. Be sure you are using a high quality cutting oil. This preserves the tool and results in a high quality final finish inside the chamber.

 

[tlawler]

I went a little deeper and I'm at .9055" now. Am I measuring to the correct point? I'm using the edge of the hood. And I'm using tap magic

 

[armorer951]

Measured from the rear of the tab to the chamber mouth, that's correct. Keep in mind though, your measurement with the depth gauge will not be as accurate as when measuring using the proper drop in chamber gauge set.

 

[tlawler]

I've looked everywhere for a set of go/no go gauges in 10mm, but there are none to be found. Pacific Tool and Machine make them and have a 6 to 8 week lead time. I don't know of any other manufacturers. Midway, Brownells and Numrich are all out of stock.

 

[toddstang]

Keep us updated!

 

[JohnHL]

I've looked everywhere for a set of go/no go gauges in 10mm, but there are none to be found. Pacific Tool and Machine make them and have a 6 to 8 week lead time. I don't know of any other manufacturers. Midway, Brownells and Numrich are all out of stock.

Try Dave Manson Precision Reamers in Michigan.

Good prices, excellent technical help, fast shipping.

I have no affiliation.
I'm just a satisfied customer.

John

 

[tlawler]

M2 conversion range test.

I finished the barrel reaming last night. Towards the end, I was taking off metal in .005" to .007" increments and reassembling the pistol to see if it would go fully into battery. I stopped at .9175" from the outer hood, when it would fully lock up. I know that's less than the SAMMI spec 10mm chamber length, but maybe the measurement on the Mauser is from the breech face? I'm not sure. With the barrel in the slide, I made sure the round was tight against the breech face with no play. I hand cycled a few mags through it and figured I was ready. My son was down this weekend from FSU for his birthday tomorrow, so I figured I'd make it a range day for the two of us. I shot it first, shooting just one round hand cycled from the mag a few times to make sure it ejected properly. Then I tried three and four at a time with no hiccups. I can only load seven in the mag because I still need to file down or drill out the dimples that held the spacer in place. After running two mags of seven through it with no failures, I turned it over to my son. He liked it so much I let him use up most of the rest of the 10mm I brought along. Altogether, we put about 150 rounds through it with the rest going into my other 1006 I bought back at Christmas. 150 rounds with not one failure! I was impressed both with the pistol and with my amateur gunsmithing skills(pats self on back). The target was shot at 21 feet. About 30 rounds were out of the M2, the rest out of the 1006. Video is of Josh shooting his first mag through the M2.

[ame]https://m.youtube.com/watch?v=u0zWBRKFC_s&feature=youtu.be[/ame]

 

[tlawler]

Try Dave Manson Precision Reamers in Michigan.

Good prices, excellent technical help, fast shipping.

I have no affiliation.
I'm just a satisfied customer.

John

Thanks, John. I'll look into Precision Reamers. If I end up doing the CS40 myself, I'll definitely want a set. I don't want to take any chances with it.

 

[armorer951]

I would suggest adding a slightly heavier recoil spring if you haven't already done so. The 10mm developes additional pressure which results in greater slide force and slide velocity rearward. A heavier recoil spring will help mitigate damage to the frame and other components by reducing/slowing the rearward motion of the slide. The desired effect of the heavier spring would be for the slide to come back to the point where the slide locks back on the last round, but only to that point. This will help to prevent the slide from impacting the frame.
An alternative would be a recoil buffer, which would also serve to prevent direct slide/frame contact that may ocurr under the added pressure of the 10mm.

 

[tlawler]

I would suggest adding a slightly heavier recoil spring if you haven't already done so. The 10mm developes additional pressure which results in greater slide force and slide velocity rearward. A heavier recoil spring will help mitigate damage to the frame and other components by reducing/slowing the rearward motion of the slide. The desired effect of the heavier spring would be for the slide to come back to the point where the slide locks back on the last round, but only to that point. This will help to prevent the slide from impacting the frame.
An alternative would be a recoil buffer, which would also serve to prevent direct slide/frame contact that may ocurr under the added pressure of the 10mm.

Is that still an issue with the rotating barrel lockup? I had read that the rotating barrel delayed the cycling just long enough that it wasn't a problem. I'll order a spring anyway. What should I go with? I figured somewhere around a 20# spring. Are the buffers universal? I've got a part number for a 10xx buffer that I was going to get for the CS40 conversion. Would it work for the M2? We were shooting Armscor 180 grain 1000fps and the recoil wasn't bad at all. If I try full house loads through it, I'll definitely install the heavier spring and buffer.

 

[oldman10mm]

When I reamed my 4053,I used a Black Talon 40S&W cartridge and a Black Talon 10mm cartridge. Measured where the 40 sat in the chamber and reamed until the 10mm sat same place. I still have to play with springs and buffers. Tested it with reduced 10mm loads(loaded down to 40 value) to verify the reaming depth. Cycles fine.

 

[tlawler]

When I reamed my 4053,I used a Black Talon 40S&W cartridge and a Black Talon 10mm cartridge. Measured where the 40 sat in the chamber and reamed until the 10mm sat same place.

That's a great idea. I hadn't thought about doing that.

 

[oldman10mm]

It was all I could think of without having to measure or use gauges. I've rebarreled Remington bolt action rifles and for that gauges were necessary. The barrel that I converted to 10mm was a barrel I picked up from Numrich. That way everything original to/for the gun stayed intact. Easy to convert back to 40S&W with the guns original barrel. the new barrel worked fine without any gunsmithing required,I got lucky.