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Old June 22, 2010, 08:03 PM   #1
wilkup
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Smith & Wesson M&P 10mm conversion?

Just toying with the idea of figuring out if it's possible to take an M&P45 and convert it to fire 10mm rounds. The reason I even thought of this is because Glock's .45 platform was based, I'm guessing, off their 10mm and I'm wondering if Smith could have the same option. I know there'd need to be a few modifications done like a different barrel, heavier springs, etc.

After having done a small amount of research on the 2 calibers I learned the case length for 10mm is a bit longer (0.992'') vs. the .45acp's (.898''). Will this be the deciding factor for such a possibility? With the difference in case length will it cause the 10mm case not to be ejected dependably, or even at all when fired?

I like the idea of having 15 rounds of 10mm vs the 10 rounds of .45acp in the gun, and the increased velocity it could offer.

If anyone has attempted this, thought about it, or successfully figured out a way to make it work -

PLEASE LET ME KNOW???
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Old June 22, 2010, 08:18 PM   #2
ohen cepel
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You have the Glock version backwards. Their 10mm (model 20) came first, then they backed it down to take a .45 (model 21).

Check into the pressures that they operate at, the .45 is a pretty low pressure round (it's old compared to the 10mm) where it 10mm is hot.

I would not attempt to convert a .45 to 10mm. If you want a 15rd 10mm buy the Glock. You'll have something that is meant to run the 10mm and much less headaches and hassle in the long run.
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Old June 22, 2010, 08:33 PM   #3
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I know the pressure on the .45acp is fairly low compared to most other loads at 21,000 psi, but I've read an article yesterday that the M&P45 can be converted to .460 Rowland which operates at 40,000 psi and that got me thinking, if that's true than it should be able to handle the lower pressure from the 10mm at 37,500 psi.

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If you want a 15rd 10mm buy the Glock
I don't particularly like the Glock 20 for any number of reasons and so if possible would be willing to figure out how to convert a M&P45 instead.
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Old June 22, 2010, 08:56 PM   #4
ohen cepel
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COTW gives the 10mm max pressure as 44,400 so that might be an issue.

Curious, have you tried to load a M&P .45 mag with 10mm (or .40 just to test it) yet? The Glock 21 holds 13 and the 20 15rds of 10mm. I'm not sure you're going to get 15rds of 10mm in a 10rd .45 mag unless there is another mag option out there. I would give it a try just to be sure. Also, if you have 10mm rds handy you can see if the mag length will support the rd, that could also be an issue.

Please don't get me wrong, not trying to rip your idea, just provide possible sticking points that may save you some time with research. I love the 10mm and wish Smith would make an auto for it again!
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Old June 22, 2010, 09:32 PM   #5
wilkup
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Quote:
COTW gives the 10mm max pressure as 44,400 so that might be an issue.
If this is true than I'm not sure how I will deal with that, but perhaps the M&P is built stoutly enough to withstand the additional pressure...? What do you think?
I haven't had the chance to load a M&P45 mag with 10mm, or even .40 to test at this point. I actually don't have a M&P45 to try this out with. I figured I would find out whether it's a possibility before I attempt the conversion. I do know, however, that there is no difference in overall cartridge length between .45acp and 10mm; they each measure 1.260'' (32.0 mm).

Quote:
The Glock 21 holds 13 and the 20 15rds of 10mm. I'm not sure you're going to get 15rds of 10mm in a 10rd .45 mag unless there is another mag option out there.
The reason I was guessing 15 rounds is because the full size Glock 22 holds 15 rounds of .40S&W and since the 10mm is the exact same size, just a bit longer I was thinking perhaps the M&P40 FS gun which holds 15 rounds would transfer over to a 10mm cartridge in a .45 mag since they're the same size?

Quote:
Please don't get me wrong, not trying to rip your idea, just provide possible sticking points that may save you some time with research. I love the 10mm and wish Smith would make an auto for it again!
I couldn't agree more!
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Old June 22, 2010, 10:32 PM   #6
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Is it technically feasible? I would think that it is. The frame size has to be large to accommodate the thick barrel and chamber which is what is going to contain the pressure. The .45 frame size is large, so S&W could build one of these. Remember that you'll have the outside diameter of the .45 barrel, but with a smaller .40 cal hole in it, which results in more meat to contain the higher pressure cartridge.

Now, back to the reality of actually making this happen: Close to zero, unless you can convince a barrel maker like Bar-Sto run off some barrels that would work. And then you'd have to concoct a new slide/breech face because the 10mm round is smaller than the .45 and while you can remove metal, it's a bit tougher to add it. Bar-Sto wants an order for 3,500 barrels before they would tool up to build something specific that they don't already make.

Smith & Wesson needs to build a 10mm M&P. Us 10 guys have been saying that for years... There's a lot of different stuff many of us would like to see S&W do, but as that old guy said... we can wish in one hand and crap in the other and see which gets filled first!

I love your idea but I don't think I'm going out on a limb when I say that you could buy a handful of 10mm pistols from different makers before you reach the cash outlay it would take to build a 10mm M&P from the ground up. Conversion? Only if you have a genie in a bottle that can build the appropriate barrel and a new slide with a smaller breech face/extractor geometry. S&W could build one in a couple of weeks. (well, maybe it'd take a little longer... but it would be worth it!)
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Old June 22, 2010, 10:36 PM   #7
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Wanted to add: OOPS -- that 3,500 number is one I either remembered, or just plain made up. I know that Bar-Sto will make anything, but it takes a large order and I don't recall exactly what it was when some of the 10 guys approached them for replacement barrels for the S&W 10xx pistols. For some reason, 3,500 is the number that popped in to my head, but I think I just made it up and then forgot to fact-check it.

It's probably not 3,500. But it's probably a helluva lot more than a 100 of them, and probably at about $150 or more for each one.
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Old June 22, 2010, 11:19 PM   #8
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Well... I guess I will just have to pray they cave and decide they want to become the #1 maker of 10mm handguns in the world and add it to their M&P line. I'm disappointed that it appears it's not possible to convert the M&P45 platform to fire 10mm, but will cross my fingers with all the other 10mm fans in hopes that they'll see the interest and take a chance to make some more money with a niche group of fans. If they're willing to build the M&P357, I don't see why they wouldn't just build the 10mm too. It doesn't make sense why they'd do one over the other when they could easily use the 45 mold to create a 10mm in their line.
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Old June 22, 2010, 11:25 PM   #9
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I think CorBon was necking down .45 cases and loading 10mm bullets, effectively making a 10mm out of a .45.
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Old June 22, 2010, 11:39 PM   #10
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What if...

Quote:
Only if you have a genie in a bottle that can build the appropriate barrel and a new slide with a smaller breech face/extractor geometry.
Would it be possible to use the M&P40 slide and internals, but get a heavy-duty barrel to put on the M&P45 frame? At this point the only thing that would been changed would be the breech length to accommodate the longer cartridge...? Would it be able to withstand the pressure that the 10mm is capable of creating? If there's a way to get the M&P to fire 10mm, I want to figure it out but having limited knowledge on gunsmithing and how such things work, hope some of you will tell me whether I'm still dreaming and crazy.
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Old June 22, 2010, 11:53 PM   #11
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Being neither an engineer nor a gun maker, I could only take the lead of a couple of known pistols and say that it would not be a good idea. My examples are Glock and S&W 3rd Generation pistols.

Glock 10's are built on a large, .45-size frame. The frame needs to be large to carry the large slide, The slide needs to be large to effectively and safely contain the barrel/chamber that houses the 10mm cartridge. Same thing with the 3rd Gen Smiths.

If you look at the .40 cal offerings from both of those platforms, you find that they are built on smaller frames with thinner slides. I believe that is a statement. Both of these gun makers built history with their 10mm pistols.

Most .40 S&W chambered pistols are built on 9mm-sized frames. I've never seen any gun maker with any pistol in 10mm built on a 9mm sized frame.

With the proper tools and equipment and barrels and barrels of money, almost anything could be built. But honestly... it will take Smith & Wesson to build this pistol because I can't see any rational, feasible and fiscally possible way anyone else could simply convert an M&P pistol to do it. Someone could do it, but it would cost them more money than anyone in the world would be willing to pay them to do it.

Aside from you personally becoming very wealthy, and then hiring someone to do it, I say it's S&W or never.
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Old June 23, 2010, 12:26 AM   #12
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Quote:
I think CorBon was necking down .45 cases and loading 10mm bullets, effectively making a 10mm out of a .45
I'd rather just add a heavier spring and go with the .45 Super and shoot Buffalo Bore's 255gr if I'm not able to actually shoot the 10mm. Part of the reason that I wanted the 10mm is because of the additional capacity it will offer over the .45
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Old June 23, 2010, 01:06 AM   #13
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visit ar15armory.com, the 10mmtalk section.

theres a guy that put an xd40 slide on an xd45 frame. the fit was not verry good and was not reliable.

there are many conversion projects on there.
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Old June 23, 2010, 05:56 AM   #14
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You have the Glock version backwards. Their 10mm (model 20) came first, then they backed it down to take a .45 (model 21).
True, except they did not back it down to take the 45ACP. They simply used the same spec's on the 10mm.

Thus the glock 21 is over engineered, so to speak, to handle the 45ACP.

I read a quote that stated,

" Once the large frame G20 was built, it was relatively easy to chamber the same brawny frame for the 45ACP, Glock's method worked far better than going about things the otherway trying to put a 10mm in a 45ACP frame, Consequently, the G21 is overbuilt and therefore pretty much a waste of strength. "

This is why you can shoot 10mm out of a Glock 21 and 30 (but not neccessarily the G36) with a 10mm barrel and mags and some suggest a change in springs although some do not.

If the M&P was not designed to shoot the 10mm I would wonder if it should? Even if it could.
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Old June 23, 2010, 06:09 AM   #15
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Quote:
I guess I will just have to pray they cave and decide they want to become the #1 maker of 10mm handguns in the world and add it to their M&P line. I'm disappointed that it appears it's not possible to convert the M&P45 platform to fire 10mm, but will cross my fingers with all the other 10mm fans in hopes that they'll see the interest and take a chance to make some more money with a niche group of fans. If they're willing to build the M&P357, I don't see why they wouldn't just build the 10mm too. It doesn't make sense why they'd do one over the other when they could easily use the 45 mold to create a 10mm in their line.
Hey if it weren't for Glock keeping the 10mm in production and relatively popular the 10mm would be even a lot less used today. Glock stuck with the caliber from the get go, so they probably know how many to make to turn a profit.

EAA Witness is the only other non-1911 10mm made and in a reasonable price point. Unfortunately, many of the 1911 10mm's are awfully $$$$ and many makers only make them in spurts. Colt's new DE 1911 is in the $800 and up range and if they ever actually bring it to marked (still delayed) the New Vltor Bren Ten will be $1000 and up.

Glock and EAA (and lets face it Glock is the far more popular gun) are the only decent price points going. I am sure that other makers looked at the 10mm and have decided that it just wouldn't be profitable enough.

The used smith 10 series are some of the best 10mm's going. Perhaps Smith got a bad 10mm taste after the 10 Series was not as popular. (it is today but not at the time)

The CZ 97 frame screams for a 10mm version. But even though the Czech Republic is right next to Austria no 10mm...

Last edited by roman3; June 23, 2010 at 07:20 AM.
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Old June 23, 2010, 06:20 AM   #16
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Just some cool info, the 10 series according to this letter was "developed" on the 45 ACP frame. Not sure the 10's weren't beefed up somehow.







And a little Miami Vice 10mm action (actually chamberd for a 45ACP as there were no 10mm blanks in 1984-85)






Last edited by roman3; June 23, 2010 at 07:18 AM.
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Old June 23, 2010, 02:37 PM   #17
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Quote:
you can shoot 10mm out of a Glock 21 and 30
How the heck can you do this

The bolt face of the .45 is designed to the dimensions of the .45. Which is larger in diameter than the 10mm. So the extractor & ejector of the .45 guns will not be reliable with smaller 10mm rounds.

Marty, my buddy got a .400 CorBon barrel for the 1911 and dropped it into a Government model. We fired it at the Seattle Police range on Saturday and it was immensely fun. The rounds were easy to load, he said. Just used the dies for .400 CorBon and the brass was necked down.

This can be loaded to maybe more than 10mm pressures because the case has more volume.

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Old June 23, 2010, 03:10 PM   #18
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Quote:
How the heck can you do this
I am quoting others, But it is a common issue at Glock talk, some say you need a conversion barrel and others don't.

KKM makes a drop in 21 to 10 mm in both standard length and 6"

http://www.kkmprecision.com/custom_p...&cat=17&page=1

Quote:
As shown in my earlier post, a 3rd Gen G21 with the LCI extractor can be converted to 10 mm with a .45 ACP - 10 mm Conversion Barrel and Glock 10 mm magazines.
A caliber conversion barrel combines the outside dimensions of the original caliber with the inside dimensions of the substitute caliber, so the firing chamber lines up with the breach face, and the barrel fits the frame and slide. If the two calibers are close in size, this works quite well with drop-in parts.
The original OEM guide rod worked, but I opted for a stainless steel guide rod and 22 lb. spring to offset the G21's slightly lighter slide, and the fact that I prefer the hotter loads (otherwise, what's the point?).
Quote:
All you need is a 10mm conversion bbl and a 10mm magazine. It works just fine and is pretty simple.
Quote:
I bought a KKM 10mm barrel, 21# Wolf recoil spring, and a couple of G20 magazines. Guess what? You are right, my G21 works great as a 10mm.
Quote:
You need a KKM 45-10mm barrel for your G21. The breechface is larger for the .45 than it is for the 10mm. I have one for my G30.
Quote:
You do not HAVE to have a conversion bbl to make the G21 shoot 10mm's. Just a stock 10mm will do fine. However, you may find that it shoots a couple of inches high at 25 yards. Reliability will be much better than 50/50. The one we have done so far is 100% reliable 100% of the time.
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Old June 23, 2010, 03:17 PM   #19
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Here is the KKM barrel conversion for the G30

http://www.kkmprecision.com/custom_p...&cat=27&page=1


And the 6" G21 drop in 10mm barrel

http://www.kkmprecision.com/custom_p...&cat=17&page=1

And here is a lone wolf G21 to 400 Corbon just like your buddies 1911

http://www.lonewolfdist.com/Detail.a...D=1476&CAT=241
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