Yes - you can - but you may need to "fit" the .40 barrel hood/lugs - depending on which barrel you have and if it's "drop in" or "fitted"????. As well, the recoil springs for the 10MM will probably have to be changed (I don't know the weight of the recoil springs on the RZ? Any help Diver, Yote, Pete, others???). And oh - the mags are different. And you may have to get a BBL bushing reamed for the .40 - depending on what/whose .40 barrel you are using??
I know that sounds like a lot - but it's not... Promise....
The rest should be just fine (slide, ejector, extractor, etc.)....
Swapping a .40 S&W barrel for the standard 10mm barrel would be no big deal. IIRC the Razorback standard recoil spring is 20 lbs., but 16-18 would make more sense for .40 S&W.
The other thing you'd probably want are .40 S&W-specific magazines. Since the .40 S&W cartridge is shorter than 10mm, the 10mm mags might not be reliable. I know Colt's .40 S&W magazines are different from the 10mm magazines, for instance.
For grins I put a 40 barrel into my 10mm once and found Castlebravo's comments to be perfect. I had to go to a 45 spring (16.5 lbs) and borrow the 40 magazines for perfect reliablity. Since we were just playing at the range it was just a trivial swap.
My question is why? You got the 10mm, just reload it to 40 level if you want that level of power.
Peter is right! if you want .40 S&W performance/power in your 10mm, buy the properly loaded ammunition to that specific level. You can handload the FMC flat point bullets to mimic the .40 S&W perfectly! There is no need to "change" your pistol's construction to meet the cartridge's configuration. Select the load you want for that specific cartridge!
Dear Baker; the 10mm automatic's acceptance into the LE community was contingent upon its ability to function over a broad "power band." The FBI wanted approximately a .40 S&W- powered load that would function reliably at minimal recoil spring levels. If the empty cases fell at their feet, this was okay.
The higher power springs being used in most 10mm will accomodate the lower-intensity loads, but may malfunction occasionally. The more vigorous 10mm loads require the use of progressivly resistant springs to prevent frame battering.
You are not ignorant. If you want to shoot 40 level loads out of a 10mm you usually do have to go to a lighter spring. I normally shoot 1/2 way between 40 and 10mm level to full power 10mm, and this is about the limit of normal 10mm springs. At the 40 level of power, feed reliablity and ejection is weak with a 10mm spring.
I was really just wondering out loud. What started my head spinning in the direction of 40S&W was when I went to buy a Tripp Mag at Brownell's (C&R's get em for $33) and I saw 40/10mm were the same mag.
Since I don't reload I thought I'd ask if the 10mm ever became extinct would the RZ become extinct too. I'm relieved to find the answer is No
And dpcdivr you offer is much appreciated!
Thanks to all for the info.
Now if my RZ ever arrives...
(edited to say) The RZ arrived and it was worth the wait! If it doesnt snow/sleet/freezing rain tomorrow it'll go to the range.