45 bottlenecked to 9mm

Yes. Small frame 10mm Typo. Missed that.

As far as the cracks on the frames The claim by Tanfoglio was the supplier and bad metal. But who knows if it was the slides and not the frames they were covering in that claim. At least by the way i read the claim it was in response to cracking frames too. Maybe i need to go back and find that and do a reread to see if there are any clues or follow ups.

But the relief cuts are not where the cracks were being reported on the frame that i was aware of too. They were most often between the safety and hammer. The reliefs would have done nothing for those. http://thegunwiki.com/Gunwiki


If i recall we had a discussion not to long ago about the relief cuts that someone thought was a crack on a 10mm frame. Then a report by eaa that it was a relief cut.

If i find anything ill post it. Its no fun getting info from EAA or Tanfoglio that is very clear.

 

A better, "more" common round similiar to this is called 9x25 Dillon. It's a 10mm Auto necked down to 9mm and has a lot of power. Can easily convert a 10mm Glock into 9x25 with just a barrel change and maybe a new spring.

But, even 9x25 Dillon has dropped out of favor because people by in large have lost interest in the elephant killing handgun calibers. 10mm has a hard enough time existing, let alone a necked down version of it.

 

You want speed? 10mm with 135s isn't that much slower than 9x25 with 124s. At that, I suspect the 9x25 numbers are based on pressures exceeding 37.5 kpsi. Point is, necking a cartridge down doesn't automatically give you more velocity. Lighter bullets and or higher pressures do that. With the bottleneck cartridge, you're then left dealing with specialized brass with a short neck. Now rather than a stupid easy loading process for a straight walled cartridge, you have to worry about headspace and neck tension. Magazine capacity isn't higher. Bottle neck pistol cartridges aren't all they're cracked up to be.

And 10mm Witnesses also had cracked slides (yes, even the non round top ones)

 

Why not have both, i dont see why a round couldnt be developed in the 45 style case necked down to a 9mm able to handle 50k+ psi shooting 124gr bullets around 2000fps. Seems like you could easily put this round in the 1911 with a compensated drop in kit and almost produce ak-47 velocitys.

I currently reload for 9mm minor and major, S&W 500 and 308w and i cant say that its all that much harder loading a bottlenecked case then it is a straight wall tho i do prefer the straight wall cases most of your high performance rounds are all bottlenecked.

 

Thompson, not to derail the thread but what are you shooting 9 major through and what's your recipe?

 

First (as far as I know) was the .38/45 Clerke.

Dean Grennell did a variant called the .38/45 Hard Head, which ran at higher pressure.

Dick Casull did his .38 Casull, which was a monster, a 124 grain 9mm (I dunno either) bullet at 1800 fps.

Someone else did a remake of the Hard Head called the SafeStop. Their web site went 404 a while back.

Any of those will work with a .45 breechface slide.

There were in-between variants:

.41 Avenger, which was a necked .45. In its recommended loading it offered no particular advantage over the .45 ACP.

.400 CorBon, another necked-down .45. In its recommended loading it doesn't offer much over the .45 ACP either, but much stouter loads are available.

.40 Super, which is a shortened .45 Win Mag case necked down to .40; it has more beef in the case head and a longer neck than the .400 CorBon and runs at much higher pressure. High-end Super muzzle energy runs in mid-range .460 Rowland territory.

--------

Here's a chart:

Here are some "representative samples" sorted by muzzle energy. (there's some variation by manufacturer, more than one bullet weight is available for each cartridge, data likely from a 5" barrel, contents sold by weight not volume, some settling may have occurred during shipment.)

(reference data)
414 ft-lb: [email protected]: .45 ACP
616 ft-lb: [email protected]: hi vel .45 ACP
618 ft-lb: [email protected]: .45 Super (basically +P+ .45 ACP)
694 ft-lb: [email protected]: .45 Super
930 ft-lb: [email protected]: .460 Rowland
1000 ft-lb: [email protected]: .460 Rowland

-----------------------------------------------------------
(cartridges under consideration)

430 ft-lb: [email protected]: .41 Avenger (.45 WM necked down to .41)
588 ft-lb: [email protected]: .400 Cor-Bon, which is a .45 necked down to .40.
694 ft-lb: [email protected]: .45 Super (basically +P+ .45 ACP)
749 ft-lb: [email protected]: .450 SMC (basically +P++ .45 ACP)
796 ft-lb: [email protected]: .40 Super, another necked down .45
871 ft-lb: [email protected]: .40 Super
891 ft-lb: [email protected]: .38 Casull (.45 necked down to .38)
972 ft-lb: [email protected]: .40 Super

The .400 Cor-Bon seems to be loaded quite conservatively, particularly when compared to the .40 Super.

---------

I had a powerful longing for a .38 Casull, but it looks like my next upgrade for my project gun is going to be .40 Super instead. At least when I lose brass it'll be out-of-the-bag Starline .40 Super instead of lovingly reformed .38 Casull wildcat brass...

 

Smaller bores make it easier to do lighter bullets, area of a pie being the radius squared and all that. Or alternately, small bores make it much harder to do heavy bullets. One other reason necked rounds don't pop up in velocity like we'd expect is due to them rapidly going over-bore for a given volume of powder; less gets burned before the faster-moving bullet exits, and even if burned completely, it's at a higher pressure due to the smaller barrel volume it can expand into, and energy is wasted. That's why your Tokarevs and 5.7's are so flashy and loud; shrinking the bullet pushes your 'ideal' barrel length further out for the same volume of powder.

Going with a sabot is actually something of the best of both worlds. Extremely rapid acceleration due to large driving surface area for powder gas, but at a very light weight, but still flying with a decent BC once separated from the sabot once out of the barrel (at a much lower pressure than for a small-bore equivalent). There, your only inefficiency factor comes from accelerating the mass of the sabot, which is usually pretty minor. The only catch is getting the thing stable and consistent enough to hit accurately, which has proved to be an issue in similar efforts like 223 Timbs (tokarev saboted to 223)

How about this for an idea, which actually does get the best of all worlds, although at (possibly) great expense; squeeze bore. Previously seen on an anti-tank cannon design, and quite effective. Basically, you have your small bore projectile with wide (diameter) driving bands, which are mashed flat inside a muzzle-tapering rifled bore. No mass loss upon exit like a separating sabot, no poor BC like a large bore lightweight bullet, and a happy median between overbore and underbore operating conditions (the one more ideal for rapid acceleration being active during the most rapid initial acceleration of the bullet, the one ideal for longer barrel length active near the muzzle). I'm a bit rusty on my high-speed aerothermochemistry, but I believe the taper also means there is no risk of mass-flow becoming choked anywhere prior to the muzzle, so there will be efficiency gains in how the gas itself speeds up and moves down the bore (namely, it won't generate shock waves off the rifling or surface roughness). The only trick here is making a precision-tapered rifled tube; very expensive for an artillery piece, but I can't help but wonder if it is effectively the same price for something as short as a hammer-forged pistol barrel.

TCB