Owner of Buffalo Bore Tim Sundles on Heavy 10mm Ammunition:
The Buffalo Bore Heavy 10 mm ammo is the result of many years of customers requests that we produce several such loads for the 10 mm.
These loads bring out the full potential of the 10mm, but operate at standard pressures and as such, are safe to use in any standard 10mm pistol.
We are using flash-suppressed powders so your vision will not be materially affected should you be required to drop the hammer in low light.
If you are firing this 10mm ammo from an autoloader and experience high extreme spreads in velocity, it is not the ammo. Here is why and how to remedy the situation.
Full power 10mm ammo has always generated enough recoil and pressure to require a pretty stiff recoil spring in your handgun - this of course depends on several variables such as your slide weight, etc. When the cartridge fires, it generates enough pressure/recoil to prematurely open your breech face in some guns. When this happens, the opening breech face has an effect on the burn rate of the powder. This can result in some fairly high extreme spreads in velocity. If you are experiencing extreme velocity spreads of more than 50 fps, simply install a stiffer recoil spring. For example, I have an original Colt Delta Elite. This gun with the factory spring runs extreme spreads of about 35fps with both of these 10mm loads. I am happy with 35 fps, so I leave the Delta Elite as is. I also have a custom built Para Ordinance with a Nowlin barrel. It runs extreme spreads of about 70 fps with its original recoil spring. When I install a spring that is 4 lbs stiffer, the extreme spread drops to about 35 fps. The new Glock model 20 comes with a recoil spring that allows the breech face to open too soon and my new Glock model 20 will get extreme spreads of about 100fps with the factory spring installed. When I go to a stiffer recoil spring, the extreme spreads drop to about 50 fps in my new Glock model 20. Of course none of this will be an issue in a revolver. None of this will be an issue in real life either, as these high extreme spreads don't hurt accuracy or function. However, I mention this because if you are like me and want things to be as correct as possible, I have outlined the problem and the solution. The industry fixed all these problems initially, by watering down the 10mm ammo over the last several years. The watered down 10mm ammo does not generate the pressure/recoil to open the breech face early. If you want the full powered 10mm ammo we make, you simply need to tweak your pistol. Or just realize that you are getting some fairly high extreme spreads and ignore it or live with it. It's not hurting any thing in reality.
Please note below, my personal velocities taken from real pistols.