1902 Carbine

[alvin]

I thought about this +P ammo business this afternoon.

In locked mode, the barrel assembly (receiver + barrel) and bolt assembly (breech block + toggle links) move at the same speed. We can imagine the total recoil energy is divided into two parts:

Total Recoil Energy: R = E + e
Kinetic Energy of Barrel Assembly: E = 1/2 Mv(2)
Kinetic Energy of Bolt Assembly: e = 1/2 mv(2)

So, the recoil energy allocation depends on the relative weight of two assemblies:

E = R x M/(M+m)
e = R x m/(M +m)

With same ammo, total recoil energy R is fixed. Energy allocated to bolt assembly cannot be too small, otherwise, the gun action may not work properly. The barrel assembly of Carbine is much bigger than that of of a regular pistol, so, much less energy is allocated to bolt assembly.

Solution 1: Increase the weight of bolt assembly.... The bolt of Luger Cabine does not look bigger and increases the weight is not a good choice anyway.

Solution 2: Decrease the weight of barrel.... not feasible, the barrel wall can only be that thin.... otherwise, safety become a concern.

Solution 3: Use hot ammo. Probably this is the reason for +P ammo.

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If above analysis is correct, +P ammo on Carbine makes lots of sense, and it's possible to turn the hard question "DWM 1902 9m/m Carbine" into a simpler question (simpler?) ..... "When did +P 9m/m ammo appear?"..... looks like this type of ammo has long/heavy barrel assembly in mind.