Lonecat Nekophrodite
First time out of the vault

In Fallout 4 there are two weapons that used .45 round
as in game names, these are
- Submachine Gun
- Combat Rifle
The former is clearly based on John Thompson designs, with a drum magazine fo M1928 and reciever of M1 (not counting modifications which I did with Gun Nut Rank 2), which in turn also saw use in Fallout New Vegas. and it is rightly designed so to use .45 round
The latter. is.. uhmmmm. it doesn't looks like it is made to use .45 round.
In this context the .45 should be the most popular .45 ACP, designed by John M. Browning to use in M1911 pistol originally. with the idea of Submachinegun being Close Combat Weapon in trench assault came to be in the mid or late WW1, the 'submachineguns' were first made using pistol cartridges, initially by Europeans, with 9mm Parabellum (which also autoloading pistol rounds, also one of popular / common rounds now saw use everywhere around the globe)
but the magazine graphics itself is too wide to fit with a relatively short .45 ACP rounds. What other 'Forty-Five' rounds should it be? .45 Long Colt? which is Cowboy Revolver cartridge that also saw use in lever action rifles.
well it can be modified to use heavy .308 rounds. and automatic firing variants exists (also weapon modifications, but it needs Gun Nut Rank 4)
What this weapons actually represents in real life? second line battle rifle? or 'cheap' assault rifle with high stopping power of .45 rounds (either .45 ACP or .45 Long Colt) and better fire control of Assault Rifles (the real life ones as in Fallout 3 and New Vegas (NCR Service Rifles for example, which itself based on AR 15 platform) and not ingame 'Steampunk rifle'
https://fallout.fandom.com/wiki/Combat_rifle_(Fallout_4)?file=FO4_Combat_rifle_full.png
as in game names, these are
- Submachine Gun
- Combat Rifle
The former is clearly based on John Thompson designs, with a drum magazine fo M1928 and reciever of M1 (not counting modifications which I did with Gun Nut Rank 2), which in turn also saw use in Fallout New Vegas. and it is rightly designed so to use .45 round
The latter. is.. uhmmmm. it doesn't looks like it is made to use .45 round.
In this context the .45 should be the most popular .45 ACP, designed by John M. Browning to use in M1911 pistol originally. with the idea of Submachinegun being Close Combat Weapon in trench assault came to be in the mid or late WW1, the 'submachineguns' were first made using pistol cartridges, initially by Europeans, with 9mm Parabellum (which also autoloading pistol rounds, also one of popular / common rounds now saw use everywhere around the globe)
but the magazine graphics itself is too wide to fit with a relatively short .45 ACP rounds. What other 'Forty-Five' rounds should it be? .45 Long Colt? which is Cowboy Revolver cartridge that also saw use in lever action rifles.
well it can be modified to use heavy .308 rounds. and automatic firing variants exists (also weapon modifications, but it needs Gun Nut Rank 4)
What this weapons actually represents in real life? second line battle rifle? or 'cheap' assault rifle with high stopping power of .45 rounds (either .45 ACP or .45 Long Colt) and better fire control of Assault Rifles (the real life ones as in Fallout 3 and New Vegas (NCR Service Rifles for example, which itself based on AR 15 platform) and not ingame 'Steampunk rifle'
https://fallout.fandom.com/wiki/Combat_rifle_(Fallout_4)?file=FO4_Combat_rifle_full.png