Home Forums Hunting & Shooting Handguns Perfect 10mm

Interesting thing about AA#9 using more powder, I did measure my 8.4 gr load of Longshot and noticed with the long 200 gr Noslers seated to 1.260" provides plenty good enough powder compression to prevent any bullet set back in the case, something I do for ALL SD rounds, whether semi auto handgun or rifle.

The S&W 610 revolver uses "moon clips" so head space chamber length is not an issue. It will chamber the 10MM Auto without them but the extractor will not eject the spent cases. You have to poke them out one by one.. COL is limited by the length of the cylinder instead of the chamber and magazine. Velocity?? Barrel gap/forcing cone vice a closed chamber? I would guess the 6.5" barrel would compensate. I don't know of any semi auto that can shoot both 10MM and 40 S&W without a barrel change of some sort. The N frame is meant for 44 Magnum so it will take the punishment. 610's are getting to stupid prices now, but one can rebore the cylinder out longer to shot 10MM Magnum, 10mm Auto, 40 S&W.

Sounds complicated with the revolver bit, been wondering where my 40's would head space in the 10 chamber after reading Sarges suggestion.

No different than the many 9mm and 45ACP revolvers. The Moon Clips provide the "Rim" to headspace on, and something for the extractor to grab.

The semi's headspace is set by the chamber. As 10MM Auto is a longer case than a 40 S&W the front rim will not headspace. The round will go forward and not be hit by the firing pin. Sometimes the chamber is tight enough to "hold" the round enough for the primer to be hit without the case moving. The extractor is some semi automatics also might do this. It would not be something I would want bet my life on however.

They're cool, but about a million dollars. lol

Yes, i most certainly would not run any 40 S&W ammo in a 10mm gun for SD purposes, my old P226 in 40 has been very good to me.

Sounds like you got a really good one and a keeper!

gunner, for what it's worth, "experts" say don't use them in your carry pieces if you've not checked the buffers and allowed them to become worn, compressed, or frayed.

I use them because I will sometimes test the boundary of max loads, on my 1911's or any other gun. Because I don't typically carry a 1911, that is a non-issue for me here.

The main reason I use the and at least one other brand is solely to protect the hardware.

Point of clarification - AA9 doesn't necessarily use more powder by volume, but it is very dense, and uses more powder by weight. In the 180-220gr range, it's just about the perfect burn rate vs volume for 10mm, as it'll reach max pressure with a full charge but is hard to get enough powder in the case to go too far over pressure. Granted there's always "that guy", but if you aren't compressing it like crazy, that's how it's always worked out for me.

Less powder weight with Longshot for the same loads is a good thing though, both for economy and a little less recoil since the powder mass contributes more to recoil than the bullet mass.

Looking back at my load data, I'm using 13.4gr of AA9 for a very similar load to your 8.4gr of Longshot. My load might be a tad hotter but probably not by much, but it definitely puts out more blast and a little more recoil without a brake. I use a brake on that 6.5" barrel, so AA9 makes sense there; I think the Longshot load is better in my non-braked barrel.

Just for fun, here are expansion test (wet newsprint) results with the 200gr Mihec bullet and shallow hollow point with the above AA9 load. The two larger mushrooms in the middle are the 6.5" longslide, and the one less mushroomed on the left is the stock G20 barrel. Penetration from both was very impressive; the faster load just made a bigger hole.

Don't do that with your 1911! It is OK in Glocks but is not safe in most other pistol platforms, including the 1911. The difference is in the firing pin/striker, and how far it can extend out of the breech face.
In a 1911, if a 40 S&W round jumps ahead of the striker in a 10mm chamber, the firing pin can still reach the primer. On ignition, that case gets slammed back past the extractor and into the breech face, and the primer may or may not get there first. I haven't seen a case actually blow out from this, but have seen them look pretty bad. The one pictured below is a good example. If you want to shoot 40 S&W for practice in that nice new 1911, you'll need a dedicated 40 S&W barrel to be safe.

In a Glock on the other hand, if a round jumps in front of the extractor (which I've never seen happen in my 10mm Glock BTW), the striker can't reach the primer, so the round just doesn't go off. There's no danger in blowing up the gun there, just a click. Some prefer to swap in a 40 S&W barrel anyway to be safe, but you don't have to in a Glock.

Note the missing chunk of the rim that was sheared off when getting pushed backwards into the extractor...


This shows maximum firing pin protrusion on a 1911 vs Glock. Note position of the pin tip relative to where a case would rest in front of the extractor.

Great info, thanks for your time and effort.

Just to clarify... though plenty of people seem to be getting away with it, I don't recommend shooting 40 in your 10mm Glock w/o a .40 caliber conversion barrel installed,

Yondering are you happy with the Para 40 ? The remington 10 mm is a Para correct?

The perfect 10mm is the 41 Magnum.

I really liked it, but the durability with the cast slide just wasn't there. It eventually cracked at the ejection port, I don't know how many rounds because I wasn't the original owner. Para replaced it (very nice of them I thought!) and I sold the gun with the new top end. It was a nice pistol though, and I'd be happy to have another. Mine was the Limited version; sweet trigger and very accurate.

I'm not sure about the Remington.

The forum won't let me edit my post above, but I shot some of those loads over the chrono again this weekend and realized I misremembered; they actually do an honest 1350 fps avg from the 6.5" longslide. Velocity from the standard barrel length is very similar to your load though.

If you're going with hard cast, I really recommend sticking with 200gr, the heavier 220 gr bullets just take up too much capacity in the 10mm and restrict it down to little more than a small bore +P .45 Auto. You'll get all the penetration you might want from a 200 anyway, and the extra velocity is a good thing. That 200gr Mihec mold I pictured above is about the best design you can get, if you can find one; you get the option of a solid WFN, or shallow or deep hollow points, to tailor the bullet for your needs.

Many Thanks CHLI, very happy to report the new 10 shot Tripp mags run flawless, feed like they should and all 5 lock the slide open when empty.

11 rounds of 10mm with 200's at 1244 is kinda confidence inspiring, particularly with two spare 10 rounders in a back pocket.

10-4, no buffers LD, I believe I'm at a safe operating area and shouldn't batter the DW at these levels, will replace springs after a thousand rounds or so.