10mm P-Series Conversion Question...

[themousethatroared]

My friend at college who taught me how to reload had a 10mm, I think it was a Glock 20, that he was really proud of. He loaded 10mm and .308 and I loaded 9mm and 5.56. We were the biggest ammo manufacturers in the little college town, going up to the range at the state park on weekends to empty the brass back out so we could reload during the week. It worked out well, because we never stole each other's brass.

So, today's episode of Really Bad Ideas That Someone Needs To Dissuade Me From Doing:
"Converting a P91 or P944 to 10mm."

Best I can tell, the chamber in the barrel would need to be cut .142 inches deeper.
The magazine cavity in the frame would have to be machined on the forward edge similar to the P90 shape to accommodate the larger round and longer magazine.
The adopted magazine would be a Tanfoglio 10mm.
Best I can tell, Tanfoglio uses a Colt 1911 pattern magazine release, so use the P90 magazine release.
Probably going to need a stiffer recoil spring, which is available from Wolff. That one leans more toward the P91 frame, because the P944 uses a nested spring.

The 1911 is available in 10mm and the barrel OD is supposed to be .580 inch, which is apparently the standard.
I don't have a P91 or P944 to measure, but the P-Series 9mm barrel is .530 inch diameter, and the .40SW barrels are enough larger than the 9mm that you can tell by looking at them, so .050 inch and probably a little more.

The internet comparison of the P90 and the 1911 in .45 cal comments that the Ruger is considered the more durable of the two. The description of the destructive testing of the P85 for the military competition makes it sound like these things would laugh at 10mm and then some. The block around the chamber was enlarged for the P90 and P91, and then the post-93 P89s got the thicker chambers. Like I said, laughing.

Is there any reason other than product liability against this?

 

[NikA]

Have you measured the front of the frame or the ejection port to determine how thin those areas will become when clearanced for 10mm? They are probably not that thick to begin with, definitely not twice as thick as required for safety (such that you could remove half to clear 10mm).

A more conservative approach would probably be to buy two frames, cut both in slightly different places, and TIG them together to provide the necessary clearance.

I don't own any P-series or I would help you measure. The typical limiting factor is not usually the barrel for cartridges operating under 40ksi.

ETA: P90 would probably be easier, 10mm 1911 magazines with new mag catch cut, custom barrel, new recoil spring.

 

[NikA]

Also, Ruger P-series use the Sauer modification of the Browning tilting barrel design, so you'd need a new barrel with a new locking shoulder position once you clearanced the ejection port...so fully custom barrel.

 

[XUSNORDIE]

My only thought....as a P Series fan......is....just because you may be able to doesn't mean you should.

Coming from a guy who never listened and said "hold my beer" way too many times and has scars to show for it.....

 

[themousethatroared]

Have you measured the front of the frame or the ejection port to determine how thin those areas will become when clearanced for 10mm? They are probably not that thick to begin with, definitely not twice as thick as required for safety (such that you could remove half to clear 10mm).

A more conservative approach would probably be to buy two frames, cut both in slightly different places, and TIG them together to provide the necessary clearance.

I don't own any P-series or I would help you measure. The typical limiting factor is not usually the barrel for cartridges operating under 40ksi.

ETA: P90 would probably be easier, 10mm 1911 magazines with new mag catch cut, custom barrel, new recoil spring.

I don't think there will be any need to modify the slide, because the frame and slide area already capable of firing and clearing 45ACP in the P90. A 45 cartridge is larger in diameter, but within a hair of being the same length as 10mm.

I don't think the ejection ports of the slides are different sizes. I measure 1.299 on the 9mm from the ejector forward, and the brass tilts at the rim and swings through the port as it comes out. The brass would clear without any problem. Ejecting an unspent round would probably not be graceful, but the action is powered by the shell being spent, so that's not possible.

The block shape for the chamber is 1.299 inches long, and there is .148 inches of the bottom of the shell sticking out the end to engage the extractor. The chamber depth would be around .844 inches.

I don't think the tilt of the barrel and lug is different between the different cartridge sizes. With the slide locked open, the breach is withdrawn up into the slide. It will be similar when it cycles.

I included the diagram of the 40SW, and the case is the same, just longer, and the walls of the chamber might need to be kissed a little so that the taper matches.

 

[the_leper_colony]

My friend at college who taught me how to reload had a 10mm, I think it was a Glock 20, that he was really proud of. He loaded 10mm and .308 and I loaded 9mm and 5.56. We were the biggest ammo manufacturers in the little college town, going up to the range at the state park on weekends to empty the brass back out so we could reload during the week. It worked out well, because we never stole each other's brass.

So, today's episode of Really Bad Ideas That Someone Needs To Dissuade Me From Doing:
"Converting a P91 or P944 to 10mm."

Best I can tell, the chamber in the barrel would need to be cut .142 inches deeper.
The magazine cavity in the frame would have to be machined on the forward edge similar to the P90 shape to accommodate the larger round and longer magazine.
The adopted magazine would be a Tanfoglio 10mm.
Best I can tell, Tanfoglio uses a Colt 1911 pattern magazine release, so use the P90 magazine release.
Probably going to need a stiffer recoil spring, which is available from Wolff. That one leans more toward the P91 frame, because the P944 uses a nested spring.

The 1911 is available in 10mm and the barrel OD is supposed to be .580 inch, which is apparently the standard.
I don't have a P91 or P944 to measure, but the P-Series 9mm barrel is .530 inch diameter, and the .40SW barrels are enough larger than the 9mm that you can tell by looking at them, so .050 inch and probably a little more.

The internet comparison of the P90 and the 1911 in .45 cal comments that the Ruger is considered the more durable of the two. The description of the destructive testing of the P85 for the military competition makes it sound like these things would laugh at 10mm and then some. The block around the chamber was enlarged for the P90 and P91, and then the post-93 P89s got the thicker chambers. Like I said, laughing.

Is there any reason other than product liability against this?

Well, if you're willing to reload, an easier (and cheaper) option might be to find a .400 Cor-Bon barrel for a P90: that's a simple barrel swap, no gunsmithing involved. Probably add a 22 pound recoil spring if you're planning to shoot full-power/10mm equivalent loads. Factory .45 mags work fine.

https://en.wikipedia.org/wiki/.400_Cor-Bon

 

[NikA]

A 10mm chamber will fully clean up a .40 S&W chamber. The taper is the same and the case mouth dimension is the same, so the reamer will just kiss (a few .0001") the walls of the chamber as it extends it to 10mm length.

Measuring a few ejection ports, 1.299" seems like it would support 10mm. As I said, I don't have any P-series guns to measure, but if all the barrel hoods are the same size, then that's a good indication that at least the slide would support 10mm.

P-series barrels incorporate a lug over the case rim (like a 1911) as opposed to having the rim recessed in the breech face (like a CZ-75), so headspace/chamber depth is properly measured from the back of that lug (which in a properly fit pistol should correspond to the breech face). Easier to chamber and check, just a note for your discussion of chamber depth (which seems to indicate a recessed breech face).

Tangfolio 10mm magazines are 1.369" between the parallel faces and ~1.40" measured parallel to the feed direction. They are .837" wide. If this were my project, I would purchase a magazine (likely the cheapest and most critical part of the conversion) and make sure that the angles and dimensions were conducive to the next steps.

The only other issue I see is that the P91 and P90 barrels definitely have different feed ramp geometries, and you may need significant modification here as well.

Good luck!