Fired my first 10mm handgun

Its a fun round to play with, very versatile. You can go from mild .40 power loads up to the nuclear type loads. I've a Gen 3 G20 and a Gen 3 29 SF both of which offer really decent case support.

Heres what I have noticed when it comes to these guns. Accuracy is such a finicky thing, some guns/ammo combos are inherently more accurate than others. I shot these with Hornady and Winchester SD rounds and accuracy was acceptable but in my mind could have been a bit better. I also chronoed these loads and they were up there velocity wise, it was kind of all over the place. The 29 seemed to exhibit this less than the 20. Once I started loading up my own rounds for it I noticed the same pattern, accuracy was decent but velocity was all over the place. Also seemed like the hotter the load the bigger the groups got. Again the 20 did not seem to show this as much as the 29. Everything I have seen says they have the same weight recoil spring. Not sure if the dual spring setup while being the same overall weight reacts differently in the early stages of firing.

Started researching as much as I could about 10mm and came to the conclusion that for the hotter loads I needed a heavier recoil spring. I elected to toy with only the 20, picked up some heavier recoil springs. Sure enough the heavier the spring the more consistent velocities became and groups tightened up, to a certain point. Finally settled on a spring weight that worked well with my hotter reloads, plinking reloads, and factory SD ammo allowing everything to cycle without a hiccup. The factory spring weight that the Glocks are currently shipping with seems to work just fine for factory plinking loads and most SD loads. If you move up to Doubletap, Buffalo Bore, or really hot handloads you may want to consider moving to a heavier spring. The lighter ones allow the slide to start moving really early in the firing process and may be robbing you of some accuracy and velocity.

Above all else keep in mind this cartridge and the guns chambered for it have their limits.
 
The G20 is the only glock I've ever owned, and I'd love to have another for a woods gun.

Buy a 40 barrel and load 40's for fun on the range, save your 10 brass for hotter loads.
 
* * * Jeff Cooper's intent for the 10mm was a 200gr bullet with an impact velocity of 1000fps. Assuming a 50yd limit, that would be 1050fps at the muzzle. A far cry from the "magnum" rounds cooked-up by D&D and Norma.
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Just to clarify, ... during the early days of the .40G&A project of the mid-to-late 1970s, which used a modified BHP, Cooper wanted to obtain a muzzle-velocity of 1050fps for the 180gn they were experimenting with. They found, instead, that they were actually getting 1100fps-1200fps easily; yet, the 180gn bullet was the limit for the .40G&A, falling short of Cooper's ideal weight of 200-grains. As Cooper had envisioned it, the theoretical "optimum" for a .40-caliber autoloading cartridge called for ".40/200gns/1000fps."

Cooper branched off from the work on the .40G&A cartridge (which, not coincidentally, has a COAL nearly identical to the .40S&W) and went with D&D to develop a longer .40 cartridge that would operate on the .45acp platform and feed-cycle. Again, it's no coincidence that the .45 and 10mm share almost the same COAL. Initially, this longer cartridge was given the "working title" of ".40 Super" or ".40 Magnum," which later officially became the "10mm AUTO."

A .45 guru and advocate of the heavier bullet, Cooper knew that the longer case would allow for a 200gn "combat load," so he upped the ballistic goal for the new 10mm cartridge to use a 200gn bullet "with a muzzle velocity of 1100fps to enable a striking velocity of at least 1000fps at the target within typical combat pistol ranges."

D&D submitted design specs to Norma for a muzzle velocity of 1200fps, in order to retain a practical striking-velocity of 1100fps at 50yds, the extra 100fps being due to the possible need to penetrate intermediate barriers encountered in the field. Norma acknowledged, however, that actual muzzle velocity for the 200gn bullet from a 5" pistol was 1152fps.

According to D&D, during all the initial experiments and back-n-forth chronograph work, they were getting velocities with the 200gn bullet that hovered between "1100fps-1150fps," which they liked. But Cooper "thought [the 10mm] needed more power, and therefore, insisted on the ammo being above that. Cooper wanted at least a minimum velocity of 1150fps. * * * This resulted in the second Norma loading being [hotter] at 1150-1200fps."

For reference, see Ron Carrillo's book: "Bren Ten - The Heir Apparent," pp. 90-94.

It's a must-read book for owners of any 10mm pistol as well as for those interested in learning the inside story, and often the hidden-history, behind the development of the 10mm cartridge and the first 10mm pistol.

See: http://www.bren-ten.com/website/id85.html

Just FYI, ... :cool:
 
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A muzzle velocity of 1125 would still be going 1100 at fifty yards.
After all was said and done, Cooper realized that there was no need for such long-range striking power (in a service pistol).
The .40 S&W is closer to being the realization of the original goal, than is a full-power 10.
 
* * * After all was said and done, Cooper realized that there was no need for such long-range striking power (in a service pistol).
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Well, his publicly expressed "regrets," in the form of concessionary statements of that sort, didn't appear until 2005 when Carrillo's book was published.

Cooper made it clear, circa 1983-84, that he had envisioned the 10mm to be the much needed middle-bore cartridge that would impart superior penetration against intermediate barriers and have "longer[er]-range striking power" than the .45acp for military use on the battlefield. The platform was to be the Bren Ten pistol. That was the prime reason Cooper wanted to keep Norma's 10mm ammo restricted to a "combat load" topped with a 200gn projectile in the form of a jacketed truncated cone (JTC). Carrillo details the very sharp and serious disagreement between Cooper and Dornaus and Dixon over their subsequent decision to expand the 10mm ammo line-up to a lighter-weight 170gn JHP for police and civilian use. Cooper was looking at the 10mm from a military prospective, whereas D&D were looking at it from a marketing prospective, particularly to cops and civilian shooters. In their eyes, there were no guarantees with military contracts. Cooper had hoped to see a military contract of some type to accelerate and fund wider production of the BT (hence, as enticement, "Special Forces" variants were built, essentially a 4.25" Commander-sized BT).

The .40 S&W is closer to being the realization of the original goal, than is a full-power 10.
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Not the FBI-Lite of 180gns @ 980fps. :rolleyes:

Well before Cooper had Norma tweak up that final 10mm load, the old Cooper standard from the middle 1970s had consistently been: a .40-caliber slug of 200gns with a m.v. of at least 1000fps.

The FBI-Lite formula, which ammo-makers transferred directly from Federal's down-loaded 10mm for the Bureau to the first generation of commercial .40S&W ammo, is actually closer to some of the early .40G&A 180gn experiential loads.

It wasn't until the mid-2000s that DT, using special hybrid powders not available in the 1980s, produced a .40S&W load using a 200gn Hornady XTP with a m.v. of 1050fps/490fpe. That load satisfies the old Cooper standard from the '70s. Before that, no commercial ammo-maker made a 200gn .40 S&W load due to the KABOOM! risk.

ETA: currently, DT offers the Nosler 200gn JHP in .40S&W, still @ 1050fps, rather than Hornady's 200gn XTP.

See: http://www.doubletapammo.net/index.php?route=product/product&path=303_341&product_id=111

:cool:
 
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It was Mike Dixon, designer of the 10mm cartridge, who was dealing with Norma. You quoted the salient parts of the book.
Coop wants 1000. To make sure, let's ask for 1100. OK, but Norma might not use a real gun barrel, so we'd better ask for 1150 just to make sure it actually goes 1100, etc., etc.
Dornaus was . . . concerned when he lit off the first Norma rounds.
 
I have two 10mm handguns....they're the Ruger Blackhawk "Buckeye" revolvers! Come with two cylinders: 10mm and 38-40. It's like shooting two entirely different handguns. The 10mm are fairly stout and snappy, although not overpowering for a 6-1/2" revolver, while the 38-40 rounds are just smooth and a pleasure to shoot. I reload for both calibers so I can cook up some nice rounds.
 
Hunter: thanks for the link and for doing that testing.

Agree with your conclusion on the PPU 10mm. I was never impressed with it.

I'd hoped that someday, since PPU gave us a 10mm loading (however lame), we might see a reasonably potent and reasonably priced 180gn or 200gn 10mm FMJ load from Fiocchi too, but so far nothing.

Too bad, because Fiocchi's other calibers of handgun ammo that I've shot have been pretty spicy as well as accurate.
 
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Best part of having a 10mm and reloading for it is, I get to look at my buddies 40 and say " nice short & weak ya got there" as I set off a 180 grainer at 1200fps.:D
 
RickB said:
I was resizing 10mm cases last night, and among them were cases from Double Tap, purveyors of factory "nuclear" ammo, and those cases, fired in a Glock (characteristic firing pin marks) were quite visibly bulged.
When I've seen bulged cases from a Delta Elite, the bulge is just ahead of the extractor groove where the case is unsupported, but the cases I was handling last night were bulged along the entire lower half, as if the chamber diameter is too large.
I won't be pushing the pressures when reloading these cases!
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That's typical of Glocks in 40s&w and 10mm from my experience. May be true of others, but I never noticed it in the 30sf 45acp, and haven't owned a 9mm Glock in a very long time so I can't speak to that.
 
It wasn't until the mid-2000s that DT, using special hybrid powders not available in the 1980s, produced a .40S&W load using a 200gn Hornady XTP with a m.v. of 1050fps/490fpe. That load satisfies the old Cooper standard from the '70s. Before that, no commercial ammo-maker made a 200gn .40 S&W load due to the KABOOM! risk.
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That's true, but that's .40 S&W at the ragged edge, probably maximum pressure. It's also 0.88 cents a round...four mags worth is $53! I mean 500 for $440?!

I load 200 grain bullets in my 10mm at 1000 fps using the starting load...10% under max. It's an accurate load, low extreme spreads (58 fps on my chronograph), easy on the brass and it can be done with several different canister powders.

No special powders or testing. It's just a very versatile cartridge and it's easy to get good performance out of it.

As a note, whenever I've tried for maximum velocity from a .40 S&W, I end up with pretty harsh recoil. It makes me wonder what the pressure curve looks like? I'm guessing it peaks a lot faster than the 10mm. Just an observation.

The 10mm isn't going away, it's my understanding Sig will be introducing a P220 in 10mm pretty soon.
 
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