Hi. Can someone tell me the difference between a StuG 40 and a regular StuG III? Thanks.

I don't know what you mean by 'regular', but initially the StuG III was equipped with a 75mm StuK 37 L/24 low-velocity howitzer and used in the infantry support role. The StuG 40 is a designated tank-destroyer equipped with a 75mm StuK 40 L/43 (later L/48) high-velocity anti-tank gun.

Stug III Ausf. A-E 7.5cm StuK 37 L/24 Gun
Stug III Ausf. F 7.5cm StuK 40 L/43 Gun
Stug III Ausf. F/8-G 7.5cm Stuk 40 L/48 Gun

When you say StuG 40, I am guessing that you mean an Ausf. F, F/8 or G version of the Stug III.

There was also the StuH 42 variant with a 10.5cm Howitzer in place of the Stuk 40 L/43 gun.

Thanks for your reply. ive always wondered why a StuG 40 wasnt called a StuG III after building the Revell reboxing of the Dragon kit. Seems there were dual roles. Thanks for clearing that up.

Yes, the F.8 and G. I couldnt see the difference between a StuG III F.8 and G and a StuG 40 F.8 and G. I guess the difference is in the barrels.

Surely it’s just another nomenclature issue? The StuG 40 was a long barrelled (initially L/43 and then L/48) StuG III so, as noted above, an F, F/8 or G.

The term Sturmgeschutz III came into use after the introduction of the Sturmgeschutz IV at the end of 1943. They used different chassis and required different spare parts, so the distinction was necessary.