A lot of folks are discovering the 10mm cartridge. It’s a great round: accurate, powerful, and incredibly versatile. That you can stack 16 of them in a handgun that shoots fast and still weighs less than an empty .44 six-shooter is a nice bonus. Hunters are taking elk-sized animals with some regularity, and animals as large as cape buffalo have been taken with the 10mm, though that’s much more of a stunt than anything else. The ethics aside, it’s a powerful round with fantastic penetration when the right bullet is used.

10mm bullets come in every weight from 60 grains to 230 grains, but the 220 grain Keith hard-cast is my current favorite. It’s probably not the most efficient, but I like the way it shoots…and penetrates. I recall seeing one video where a 220 grain hard-cast went through-and-through 18 one-gallon plastic jugs full of water, lined end to end. They never found the bullet. It doesn’t expand, but the Keith-style bullet does create a good wound channel, and it’s very resistant to deflection…straight line wound tracks are expected.

There are several sources for 220 grain hard-cast bullets, but virtually no published loading data for that bullet. Boutique manufactures (Underwood) get 220 grain hard-cast bullets up to 1200~1250 fps, but they cost a buck-a-round. That’s actually pretty good economy, all things considered. I’ve loaded up to those levels and decided that I’m pretty happy to pay Underwood to do it for me. He’s better at it than I am. (I get 1235 fps from the Underwood 220 grain load and 1290 fps from the Underwood 200 grain hard-cast out of a 6” barrel.)

Shooting 220 grain bullets is good fun…and good practice. A 220 grain bullet going 1000~1100 fps mimics the recoil of the Underwood 220 grain load close enough that you’d need to fire hundreds of them to tell much difference. And a 220 grain bullet going around 950 fps exceeds the ballistics of the vaulted .45acp, and still makes the 10mm feel like a pussycat…or at least a pussycat compared to a full house 10mm load. Drop the velocity below 800 fps and recoil becomes a non-issue, but it still has more penetration than the .45 auto because of the superior ballistic coefficient of the .400 bullet.

Since there's no published load data for the 220 grain hard-cast, I’ve been working up some loads with different powders. If you want to reload 220 hard-cast in 10mm, you’re off the reservation. Needless to say, this is only of value to people already familiar with loading handgun cartridges.

Also, just because you can throw a 220 grain bullet at 1200+fps doesn’t mean that you want to all the time. Those loads are hard on the gun, hard on the brass, and hard on the shooter. Many handguns won’t even cycle them reliably without changing out the recoil springs. Downloading the 220 grain bullet for every day shooting makes a lot of sense. Subsonic loads make reasonable small game getters…not ideal, but the non-expanding bullet doesn’t destroy all the meat, and the reduced muzzle blast and recoil is much appreciated when your the hunter, not the hunted.

I’ve been carrying a .357 snub-nose revolver for years. It’s a fantastic gun because at 11 ounces you can literally cary it in your front pocket and still be comfortable, but it’s got some drawbacks: short on round count, long on recoil. So when I’m traveling around large furry things, I favor a 10mm, when I think the weight is warranted. The 10mm recoil is significantly stouter than other semi auto cartridges, and it requires considerable practice to shoot well. I practice with what I cary, so when I’m shooting USPSA or Steel Challenge, I use my 10mm. Downloading to around 1,000 fps is still a ridiculous amount of power for those matches and means I’ll never be competitive, but it’s a good compromise between being able to shoot that medium, and still use the gun/load I cary in the woods. And even at 1,000 fps, no one at the match is going to confuse you with any other shooter…

Powders:
Lots of different powders are used to load 10mm because there are so many different bullet weights available, but not all of them are ideal for the heavy bullets. HS-6 showed overpressure signs pretty quickly with the 220 grain bullet, and Blue Dot, which is a staple for magnum 10mm loads in other weight bullets, showed overpressure at comparatively low velocities while pushing the 220 hard-cast. Of the powders I’ve used (Blue Dot, HS-6, Longshot, AA#9, and Hi-Skor 800-X) Longshot and 800-X seem to be the best choice for getting peak velocity without overpressure. Unfortunately 800-X meters like course gravel. It won’t flow through my powder drop at all, so all loads have to be weighed out with a spoon.

Longshot, Blue Dot and AA9 all seem to work well for low to medium loads. AA9 meters the best, but it’s also the most expensive powder since it costs more to begin with, and it requires almost twice as much AA9 as Longshot to get the same velocity. Blue Dot has noticeably more muzzle blast than other powders, but is very accurate out of my barrel.

DISCLAIMER…PLEASE READ, THEN READ AGAIN:

These loads ARE NOT RECIPES, they are for reference purposes only, and accomplished re-loaders will get some possibly useful or un-useful data from them, but that is all. They are not proven in different guns, different barrels, or with different batches of the same powders, or with different brass, primers, or crimps. The fact that they did not blow up my gun in no way-shape-or-form means they won’t blow up your gun, and take your hands and face with it! There are far too many variables in how pressure builds and then drops in a pistol cartridge to consider any of this data a proven recipe. If you’re new to reloading don’t start here…this is not the place to begin.

Thanks!

All loads are 1.26” COL with a light taper crimp and WLP primers in assorted brass. Most charges were hand weighted, but some were thrown with the powder measure, hence the greater difference in velocity. Chronograph is approximately 15 feet from muzzle.
Gun: Glock 20 with 6” KKM Barrel and 22 lb recoil spring.
Rim Rock 220 grain hard-cast bullets, .400 diameter, lubricated with Lee Liquid Alox. (Note: many hard-cast bullets are .401 or even .402 diameter and will show different pressures than the .400 bullet.)
4,700 feet MSL

Again...
DO NOT BLINDLY DUPLICATE THESE LOADS! THEY ARE NOT PROVEN SAFE IN ANY COMBINATION OF GUN, SPRINGS, AND BARREL OTHER THAN MINE. CHANGING ANY COMPONENT OR LOADING PROCEDURE COULD CREATE AN OVERPRESSURE AND DAMAGE YOUR FIREARM OR PERSON. IF YOU’RE NEW TO LOADING THE 10MM, DO NOT START HERE!!

LONGSHOT POWDER:

4 Grains Longshot:
737, 727, 709, 741, 700 = average 722

4.5 Grains Longshot:
790, 796, 771, 797 = average 788

5 Grains Longshot:
842, 881, 876, 880, 869, 900, 915, 866, 847 = average 875

All loads of 5 grains and below required the factory Glock gen 4 spring and would not function reliably with the 22 lb LW spring.

5.4 Grains Longshot:
927, 937, 922, 937, 934 = average 931

5.6 Grans Longshot:
931, 942, 951, 948, 940 = average 942

6 Grains Longshot:
1010, 998, 955, 983, 998 = average 989

6.4 Grains Longshot:
1022, 1066, 1071, 1069, 1024 = average 1,064

7.2 Grains Longshot:
1081, 1082, 1077, 1081, 1082 = average 1,080

BLUE DOT POWDER:

6.0 Grains Blue Dot:
881, 907, 910, 865,858, 884, 908, 885, 880, 882 = average 887
Failure to function with LW 22lb spring. Use factory Spring.

6.5 Grains Blue Dot:
986, 962, 972, 950, 942, 987 = average 962
Less recoil than 7 grain loads by a significant factor.

7 Grains BlueDot:
1001, 976, 1018, 1012, 1004 = average 1,002

7.2 Grains BlueDot:
982, 1011, 978, 992 1037, 1024, 1031 = average 1,009

7.4 grains BlueDot:
1031, 1038, 1021, 1049, 1034 = average 1,034

7.6 Grains BlueDot:
1060, 1050, 1039, 1038, 1045 = average 1,046

8 Grains BlueDot
1080, 1064, 1071, 1071 = average 1,071
Absolute limit for BlueDot Powder. Heavier loads gave minimal velocity increase but showed overpressure signs with used brass, including gas cutting around the primer.

800X POWDER:

7.6 Grains 800X:
1128, 1142, 1137, 1152, 1157 = average 1143

7.8 Grains 800X:
1167, 1177, 1148, 1158, 1185 = average 1167
Primers starting to flatten out.

AA9 POWDER

8.0 Grains AA9:
874, 851, 860, 878, 878, 886 = 871 average
Requires factory spring

8.5 Grains AA9:
912, 918, 899, 919, 903, 910 = 910 average

8.8 Grains AA9
972, 954, 951, 962, 953 = 958 average

A word on shooting lead bullets through factory Glock barrels:
It’s fine, just clean the barrel every fifty shots or so to keep lead from building up to the point pressure increases. I get leading in my KKM barrel, and I clean it with a copper chore-boy wrapped around a patch jig. Just a few swipes and all the lead is gone. Because Glock (and some other) barrels are not fully supported, the higher pressure loads can create a “smile”, or crease line where the unsupported brass was sheared by the barrel edge. Some Underwood factory loads will smile in a Glock barrel. This brass is not reusable and must be discarded. The smile can be quite faint, but it’s fatal. Look carefully and throw away any brass you suspect might be smiled, as resizing it will not fix the molecular damage.

Loads that go over 1,100 fps usually mean discarding the brass, though new brass will sometimes be reusable. Loose primers are the problem, and I have a garbage can full of clean, resized 10mm brass that the primer set too easily in. In the interest of keeping my brass healthy for more than one loading, and being able to load with a powder measure rather than weighing every charge, I've got a personal limit of 1,050 fps for reloading 220 hard-cast bullets in used brass. For the Hiroshima loads I'm happy to buy ammo from Underwood...

I love the 10!

I’ve only shot WT deer and pigs with it but performance is respectable.
I don’t hand load. Don’t have the time for another hobby.
I’ve had good luck w/Buffalo Bore 220 hardcast.

I’ll be in Kodiak in November deer hunting and have vacillated between taking a Glock 10 or a Ruger Alaskan 44. Right now I’m leaning towards the 44 only because it’s been sitting in the safe since I purchased it and I’ve never carried it.

Sierra Victor wrote:I love the 10!

I’ve only shot WT deer and pigs with it but performance is respectable.
I don’t hand load. Don’t have the time for another hobby.
I’ve had good luck w/Buffalo Bore 220 hardcast.

I’ll be in Kodiak in November deer hunting and have vacillated between taking a Glock 10 or a Ruger Alaskan 44. Right now I’m leaning towards the 44 only because it’s been sitting in the safe since I purchased it and I’ve never carried it.

10mm is indeed a good round! And reloading is absolutely a hobby...if your time is worth anything, it's not a savings.

I can see why you haven't carried the Ruger Alaskan... damn near three pounds and only six shots. I'd love to love large caliber revolvers, but I know I just won't cary one...ever. Too much weight, too little poop. But if you've got it you might as well get some dirt on it!

Regarding factory loads: BB ammo usually makes (close enough to) stated velocity and seems to have good quality control. But the owner (Tim Sundles) is a convicted wildlife poisoner, and an admitted poacher, and he'll never get a nickel of my money. On top of that, I've seen some e-mail correspondence between customers who had problems with BB Ammo and Sundles, and his response is basically "I'm an expert and you're a moron, so go to hell for suggesting anything I created wasn't perfect." He phrased it slightly more eloquently, but not by much.

Compare that to Underwood (which usually comes in above stated velocity)...I contacted him regarding 220 loads not ejecting from a stock Glock and asking for guidance. He pulled rounds from the same batch and test fired them, then said they were up to speck, but it wasn't unheard of for that round to cause problems in stock guns. He advised going to 200 grain loads, or trying different recoil spring weights. I'm an Underwood fan, just like I'm a Light Speed fan...customer service means a lot to me.

Hammer wrote:

Sierra Victor wrote:I love the 10!

I’ve only shot WT deer and pigs with it but performance is respectable.
I don’t hand load. Don’t have the time for another hobby.
I’ve had good luck w/Buffalo Bore 220 hardcast.

I’ll be in Kodiak in November deer hunting and have vacillated between taking a Glock 10 or a Ruger Alaskan 44. Right now I’m leaning towards the 44 only because it’s been sitting in the safe since I purchased it and I’ve never carried it.

10mm is indeed a good round! And reloading is absolutely a hobby...if your time is worth anything, it's not a savings.

I can see why you haven't carried the Ruger Alaskan... damn near three pounds and only six shots. I'd love to love large caliber revolvers, but I know I just won't cary one...ever. Too much weight, too little poop. But if you've got it you might as well get some dirt on it!

Regarding factory loads: BB ammo usually makes (close enough to) stated velocity and seems to have good quality control. But the owner (Tim Sundles) is a convicted wildlife poisoner, and an admitted poacher, and he'll never get a nickel of my money. On top of that, I've seen some e-mail correspondence between customers who had problems with BB Ammo and Sundles, and his response is basically "I'm and expert and you're a moron, so go to hell for suggesting anything I created wasn't perfect." He phrased it slightly more eloquently, but not by much.

Compare that to Underwood (which usually comes in above stated velocity)...I contacted him regarding 220 loads not ejecting from a stock Glock and asking for guidance. He pulled rounds from the same batch and test fired them, then said they were up to speck, but it wasn't unheard of for that round to cause problems in stock guns. He advised going to 200 grain loads, or trying different recoil spring weights. I'm an Underwood fan, just like I'm a Light Speed fan...customer service means a lot to me.

Wow! Wasn’t aware of the BB owner’s philosophies and transgressions.
I’ll have to look into for myself but it sounds like I’ll be switching to another manufacturer.
Thanks for the info.

BTW have you found an off the shelf 220 hardcast load that works for you?

I don't think I've see any 220 grains in stores aside from BB.

Doubletap shows up every now and then, but they greatly exaggerate their velocities...it never chrono's close to what the box says.

Underwood has flat rate shipping...$7.50 for as many rounds as will fit in the box, if I recall correctly. I've been nothing but impressed with every round I've bought from him.

A buddy of mine has a Desert Eagle in .50AE.
Dunno if anyone loads solids for it, but it'll throw a 300 gr JHP at 1475, per Hornady.
Big and heavy, but maybe / probably as fast to shoot as the Glock

My wife and I live in bear country here in the Wrangell mountains and both carry 10 mm Glocks in Kenai chest holsters -- great combination for powerful and ready protection. We have larger caliber revolvers, but they arn't as versatile as semi-automatics. If there is one thing we have observed, bear attacks happen fast and rarely allow a lot of time to react. My neighbor got mauled by a grizzly while on a sheep hunt a couple of weeks ago and all he had was his rifle for protection. He got a hip shot off but never got another chance to reload. He could probably have gotten several shots with a semi-automatic.

Nizina wrote:My wife and I live in bear country here in the Wrangell mountains and both carry 10 mm Glocks in Kenai chest holsters -- great combination for powerful and ready protection. We have larger caliber revolvers, but they arn't as versatile as semi-automatics. If there is one thing we have observed, bear attacks happen fast and rarely allow a lot of time to react. My neighbor got mauled by a grizzly while on a sheep hunt a couple of weeks ago and all he had was his rifle for protection. He got a hip shot off but never got another chance to reload. He could probably have gotten several shots with a semi-automatic.

Your wife must have strong hands! What load are you using in the 10mm?

I've always thought the 10mm Glock was superior to large bore revolvers, but I've got north of 100,000 rounds through Glocks, much of it under simulated combat, so it'd be ridiculous for me to go to a different gun. Starting from scratch I don't know what I'd choose. The .44 has better ballistics, while the 10mm has adequate ballistics and the ability to shoot faster and longer. Calibre is of no consequence if you don't hit the target, and I think it's a little more practical to do extensive shooting with the 10mm. I need around 3,000 rounds a year to be on my game, and twice that is better. .44's are expensive...even with reloading that's a significant chunk of change. Hard on the wrists, too.

Many folks tout the superior reliability of revolvers, and there's something to that, but not as much as advocates would have you believe. With the wrong ammo selection revolvers will freeze solid...either from bullet-pull jamming the cylinder, or from a primer melting into the firing pin hole, or the firing pin penetrating the primer and being captured, thus jamming the cylinder. Those malfunctions, while not common, cannot be fixed in the field. The scandium/titanium revolvers are especially prone to bullet pull, because they are so light and recoil so sharply. Cartridges need to have a tight crimp to be reliable in them, and a bullet adhesive isn't a bad idea.

Semi-auto's (well, Glock's, anyway), are pretty darn reliable once the selected ammo is tested and proven for each magazine. But proving a load can get expensive. I spent over $100 on Underwood 220 grains before I was convinced my spring/barrel combo was up to par, and then only for one of my five magazines.

I guess with either platform it's incumbent on the user to shoot enough of their cary ammo to be sure it will work. Unless you really enjoy shooting, it's another good argument for a $40 can of bear spray...

An interesting segway regarding ammunition...

I've always wondered how waterproof ammo is...how wet is too wet to be reliable? On patrol I swapped out my ammo frequently during the rainy season, though none of the ammo I swapped out ever misfired when I shot it later on.

Recently I was cleaning some 10mm brass in a ultrasonic cleaner after a pistol match, and when I scooped the brass out I found I'd thrown a live round in as well. It had spent 25 minutes in a 160-degree ultrasonic solvent and water solution. Out of curiosity I pulled it apart...the powder was completely dry and the primer worked perfectly.

This honestly surprised me. It was just a cast-lead reload...no bullet adhesive, no sealant on the primer, not even a secondary crimp. I realize one round doesn't tell the whole story, but I thought it was interesting. I might take a dozen random reloads and toss them in a bucket of water for a week and then pull them apart.

Hammer wrote:<snip>
This honestly surprised me. It was just a cast-lead reload...no bullet adhesive, no sealant on the primer, not even a secondary crimp. I realize one round doesn't tell the whole story, but I thought it was interesting. I might take a dozen random reloads and toss them in a bucket of water for a week and then pull them apart.

1. Um, what is "bullet adhesive"?
2. Looking forward to the post-immersion results...

Some commercially produced ammo has an adhesive to keep the bullet from setting back into, or pulling out of the case. It's not real common, but not unknown by any means. I'm familiar with it being used in revolver ammo that's very light for caliber to prevent recoil induced bullet-pull due to the reduced surface area of the lighter (short) bullet, or in pistol ammo that's loaded very hot or with unusually heavy for caliber (long) bullets, in order to prevent bullet setback when the round hits the feed ramp, which would dramatically increase chamber pressure. All the ammunition I'm aware of that incorporates it is high-end law enforcement ammo with a correspondingly high price tag.

In the early days of .40 S&W, the 180 grain loads had a reputation for going K-Boom...the result of a round that's already loaded to the limits of case pressure going over-pressure because the bullet got pushed back in the case...usually from being chambered several times with the associated ramp-strike every time it was chambered. This was a bit of a surprise to the autoloading community, as the "other two" autoloading rounds (9mm and .45acp) were not normally loaded so close to the pressure limit of the case and rarely went K-Boom.

The .40 K-Boom syndrome seems to have mostly gone away...probably the result of commercial loads incorporating a slightly reduced powder load and a stronger crimp, and the general public learning not to chamber the same round more than two or three times. But it's exactly what bullet adhesives were meant to address.

Bullet adhesive is probably used in other applications, but those are the ones I'm familiar with. It's not common in hand loading as it vastly increases the time and complexity it takes to load a round, and it probably has an influence on pressure levels that the typical hand-loader doesn't have the time or technical expertise to deal with. Given the increased production and R&D costs of using a bullet adhesive, you can see why it's not real popular, even with factory loads. Much easier to incorporate a tighter crimp and/or a reduced powder level.

I always suspected that ammunition used by underwater military forces was constructed differently than "normal" ammo to address the underwater environment, but maybe not. I don't know much about military ammo.