According to multiple sources MAB M38/42 we can see that it always had fire rate of 550 rpm not 500/min we have right now. Muzzle velocity also should be faster from 400 → 430m/s
"This new model, the Model 38/42, had a fluted barrel to aid cooling and save weight. It also had a slower rate of fire (550 rpm). "
“38/42: Barrel length reduced to 213 mm and a reduced two-slot compensator. The weapon is lighter, using sheet metal stampings with a dull blue/black finish. A fluted barrel helped dissipate heat and reduce the weight down to 3.27 kg. The RPM reduced to 550. The effective range is 150-200 meters.”
In the 38/42 and 38/44 versions
(photo no. 7) the need imposed by the war events
to accelerate production as much as possible
slightly lowered the level of fi nishings which however
always remained more than good for a military
weapon. The purchased specimens were then
stored and distributed only to a few elite
units, such as the paratroopers and the Engineers,
starting in 1941. The Royal Navy
purchased several thousand of them which were assigned
to the San Marco Regiment and the surveillance units;
the Royal Air Force assigned it to the
ADRA regiment. The reports from the combat units on the
behavior of the weapon were all very
positive and from 1942 all the special units of the Royal
Army were equipped with them in greater
numbers: the 10th Arditi Regiment, the
“Monte Cervino” Ski Battalion, the “Folgore” and “Nembo” Paratrooper
divisions, the Engineers’ Guastatori and
significant numbers were assigned to the “M” Battalions of the
MVSN
M38/42 (or 43) elite SMG carrying engineer/paratrooper event squad when?
M38/A with bayonet, it’s muzzle velocity irl was insignificantly faster by 2m/s so no need to correct that mistake.