I love 10mm. I love Underwood Ammo. The first time I tried their 220gr hard cast with my 10mm, I loved them. Then I found out that Underwood uses Rim Rock Bullets out of Montana. I had no idea of what the powder was nor the amount. Then I found this site: https://docs.google.com/
Loud and clear: whoever owns that list is worthy of all love, praise and honor. We spread our finest meats and cheeses before you. Thanks, my friend. If you are 10mm fan boy, go here: http://10mm-firearms.com/ This is THE premiere 10mm site.
So, I bought 300 of the 220gr HC from Rim Rock. The box arrived from USPS and lifted like a bowling ball. So far, so good. I had purchased BE-86 powder for this very purpose. And the load data said "8 grains of BE-86."
Having case prepped all of my 10mm cases, I then began the micro-tuning of how much 'belling' of the case mouth to do. All I can say is to not do this when you are in a hurry. Be willing to sacrifice some bullets to the process. Once you find that perfect amount that enables you to seat the bullet without shaving off metal, you will be glad you did.
Initially, I made 10 of these. When I fired them, I used my Glock 40 with NDZ heavy guide rod, KKM match, threaded barrel, and the Carver Custom 4 port compensator. Atop the G40 is a Vortex Venom red dot. At 20 yards, I was dead on target. In this case, my target was a piece of mesquite wood found near by. Roughly 4 feet long and 6 inches in diameter. I pushed it into the wet ground. I then proceeded to drill holes in the wood with these bullets. The combination of compensator and heavy guide rod (24 lb) provided soft shooting and zero issues with feeding and returing to battery.
If you have a chance, order some of these 'bowling ball' rounds from WWW.RIMROCKBULLETS.NET
Again, I can't thank www.10mm-Firearms.com enough. I used the following data from their site:
| Ballistics Information: | 10mm Auto |
| Muzzle Velocity: | 1200 fps |
| Muzzle Energy: | 704 ft. lbs |
| Brass Make/Headstamp: | Starline - Nickel |
| Bullet Make/Weight/Construction/Info: | Length 0.7270”/Dia. 0.4005”: 220gr. Hard Cast FN |
| MEPLAT: | 0.3000” / Flat Base |
| Actual weight: | 214.6 / 214.2 / 213.8 grains Crimp squeezed bullet to 0.3990” |
| C.O.A.L.: | 1.2445” / 1.2420” / 1.2430” |
| Primer: | Large Pistol Primer Nickel color |
| Case: | Diameter 0.4215” Crimp Diameter 0.4220” (Tight) Length 0.9870” |
| Powder Description/Positive ID/Type/Charge Weight: | BE-86 8.0 / 8.0 / 8.0 grains (Changed originally posted this as Power Pistol) |
| Cartridge weight: | 298.8 / 297.6 / 298.4 |
Yes, I chronographed them. No, I did not retain the data. I screwed up. Will be re-doing and updating.
As always, these are only opinions - never instructions or recommendations.