So at the knob creek mg shoot (God rest its soul) I ran into a vendor selling a .40 SW MAC10 upper. Good guy with a solid rep, and we started talking. The initial conversation was about doing a MAC10 upper in 10mm, and he recomended a lage upper to start with, because it would allow you to tune for the heavier caliber a little easier. From there my deranged little mind started thinking, if 10mm is viable, how about a 9x25 dillon (I love that round, I know it is niche, expensive, and oddball, but hey, what cool things aren't?)

Here is what I am thinking...
1 Get a lage Max10/9
2 Open up bolt face for the 10mm base
3 Rechamber barrel for 9x25 dillon
4 Tweak grease gun feed lips to function correctly (host is a powder springs M10/45)

I know I am going to have to mortgage my home to feed it, but the idea just won't die. Any thoughts or issues I'm missing?

I don’t know how well an open bolt would hold up to a 9x25 Dillon . I’m pretty sure that cartridge was designed around a locked breach. 9x25 Mauser export might be a more feasible cartridge in theory but getting it to feed in a magazine might be tricky. Might have to use modified steyr mp34O magazines. I have no idea on the chamber pressure of a 9x25 Dillon though. A 7.65mm Mauser conversion would be easy and allow you to shoot Russian 7.65x25

Haha, you must have been there. Yes, it was Troy, seemed to be a good guy and very knowledgeable. The feeding is my main concern. Also Lage's bolt setup, would the 9mm bolt run from grease gun mags OK? I think I need to call Richard and bug him, don't know if he would want any part of this project though, guess I'll find out.

ETA- I am setup to reload the dillon, so I have that going for me, which is nice. I figure if all else fails, as long as the bolt feeds from the gg mags ok, I can just have troy cut a 10mm barrel for it when he can get blanks and give up on the dillon after losing nothing but ammo and time.

If you end up doing this, please post a video of it firing. With that powerful cartridge, the cyclic rate would be absolutely insane; probably close to 2,000 RPM.

I'll keep updating as I go. I saw a guy who did a standard upper 10mm and that is what got me interested. He had the bolt modified, found an m10 barrel in 10mm (he couldn't remember from where), and ran modified gg mags. Had pics of the finished gun, but no use videos.

22LR
9MM
45ACP
5.56 NATO
7.62 NATO
"Cheep", plentiful, and reliable.

That's all you need.
Spend the money upgrading to an UZI, M16 or M1A1.

You asked

Something that comes to my mind is the mass of the bolt. Especially with ammunition on the high end  of the power range, 10mm is much more powerful than  .45. So would a M10 bolt with a bolt face opened up for .40 caliber 10mm, would the bolt have enough mass to hold the shell far enough into the chamber such that the side of the shell wouldn't rupture? I don't know, I am asking?

Scott

Due to bottleneck 9x25 also has more bolt thrust than 10mm, so the bolt would need to be even heavier.  Personally if I was doing this I'd try to figure out a gas operated system instead of straight blowback.

Being fortunate enough to own a Ron Williams 7.62x25 DI upper which uses a pistol length gas tube and the 9X25 Dillion round is even more powerful, I would want someone to figure out how much mass the bolt actually needs to operate safely. As I recall from the Thompson book, 30.06 would need a blowback bolt with a mass of 42 lbs. With the 9X25 Dillion round pushing the medium caliber rifle round energy range. Would a Lage upper even with the additional bolt weight being tungsten, be enough mass to safety run this round?

There is not only the issue of the mechanical bolt mass system of blowback,  but where is all that recoil energy going? Both the S.A.B.R.E. and the Lage Max-10/15 use the AR rotary locked system which splits the recoil energy of medium power rifle rounds with the front and the back of the Mac style receiver. Some of the recoil energy goes into the bolt lugs of the barrel to the front pin of the receiver. The unlocked bolt group recoils against the mechanism spring which is held by the back plate of the receiver. The blowback upper of a M10 has 90 something percent of the recoil energy directed at the back plate of the receiver. We are  talking a 125 grain bullet going 1,500 or 1,600 ft/sec out of a pistol length barrel. I don't know as the M10 receiver was designed for that kind of recoil energy on the back plate.

Could this project be physically assembled? I am sure that it could. My concern is the engineering involved with using such a powerful round with a straight blowback system. Is it a cool project? Absolutely, but I would want some engineering to be sure that this would be safe for me and my $8,000.00 market valued receiver. Good luck with the project

Scott