Guns are so fun. Start looking for one thing, and a bunch of new interesting things pop up.
While looking for the Gun Trifecta (handgun, PCC (black semi-auto), and lever gun all in same pistol caliber), I ran onto the idea of shooting 40S&W in a 10mmAuto gun. Turns out, 40S&W is a direct descendant of 10mm.
The 40 S&W is 3.6mm shorter than a 10mmAuto but is the same in every other way. Most commercial ammo have very similar muzzle velocities for the same bullet (e.g. American Eagle 180gr is 1030fps for 10mmAuto (5"barrel) and 1000fps for 40S&W (4"barrel); ballisticsbytheinch.com indicates this difference is likely entirely due to the barrel length). S&W actualy just cut down the length of the 10mm, eliminating excess space in the case when using typical loads. Obviously, having 3.6mm extra capacity, a 10mm custom or hand load can be made quite a bit hotter. 10mmAuto guns are built to accept this extra pressure of hotter loads and will handle the lower pressures of standard 10mmAuto or 40S&W loads just fine.
Since rimless cases are held against the bolt face by the extractor, the shorter 40S&W generally works fine in a 10mm gun. The case slips in behind the extractor, rather than with a rimmed cartridge that the extractor snaps over the cartridge rim.
This is not theoretical. I have ready reports from many shooters who regularly shoot 40S&W from their 10mmAuto handguns. This seems especially common with the Glocks 20.
There are likely exceptions to this rule, so before attempting this, do some research on your gun.
By the way, it would appear that the key to do the Trifecta is a Marlin 1894 modified by Grizzly Customs to fire 10mm (which may or maynot work with 40S&W and may or maynot be available to Canadians). 40S&W are readily available for handguns and black semi-auto PCCs.
While looking for the Gun Trifecta (handgun, PCC (black semi-auto), and lever gun all in same pistol caliber), I ran onto the idea of shooting 40S&W in a 10mmAuto gun. Turns out, 40S&W is a direct descendant of 10mm.
The 40 S&W is 3.6mm shorter than a 10mmAuto but is the same in every other way. Most commercial ammo have very similar muzzle velocities for the same bullet (e.g. American Eagle 180gr is 1030fps for 10mmAuto (5"barrel) and 1000fps for 40S&W (4"barrel); ballisticsbytheinch.com indicates this difference is likely entirely due to the barrel length). S&W actualy just cut down the length of the 10mm, eliminating excess space in the case when using typical loads. Obviously, having 3.6mm extra capacity, a 10mm custom or hand load can be made quite a bit hotter. 10mmAuto guns are built to accept this extra pressure of hotter loads and will handle the lower pressures of standard 10mmAuto or 40S&W loads just fine.
Since rimless cases are held against the bolt face by the extractor, the shorter 40S&W generally works fine in a 10mm gun. The case slips in behind the extractor, rather than with a rimmed cartridge that the extractor snaps over the cartridge rim.
This is not theoretical. I have ready reports from many shooters who regularly shoot 40S&W from their 10mmAuto handguns. This seems especially common with the Glocks 20.
There are likely exceptions to this rule, so before attempting this, do some research on your gun.
By the way, it would appear that the key to do the Trifecta is a Marlin 1894 modified by Grizzly Customs to fire 10mm (which may or maynot work with 40S&W and may or maynot be available to Canadians). 40S&W are readily available for handguns and black semi-auto PCCs.


















































