40x46mmSR

Being a gun guy and a gamer, I ask questions that don't seem to occur to the authors.

I'm doing research about equipment for a SEAL platoon working in the Mekong in late '67 early '68.

The players will have their choice between the M79 and XM148 grenade launchers.

The question is about the length of the rounds.  The XM148 is conceptually similar to an M203.  It mounts under the barrel of an M16 and the barrel of the GL slides forward for loading.  Some rounds, like the parachute flare M583 are quite long, 5.272".  The normal HE round in Vietnam is the M381 and it's 3.89" long.

The rules as written indicate that some 40mm grenades are considered "long" and that the M203 cannot use "long" rounds.  The problem I have is that I know for damn sure the M203 can use the M583.  The rules indicate that a parachute flare is an "illum" round and those are "long".

Damn reality messing with a perfectly good rule.

The stats I have for the XM148 predate the "long" rule, so I don't even have that for guidance.

So I grab the internet and start looking for pics.  The M203 appears to open 4.83".  The XM148 appears to open 4.27".  I scaled off of photos so there's prolly a ±0.075" here.  If I assume that the M583 just barely fits and is the maximum length round you can load in an M203; then an XM148 cannot load any rounds that are longer than 4.7" or so (assuming the same geometry).

Basically that means that if the 40mm round has a parachute, you cannot fire it from an XM148.

Also listed in the equipment with the rules as written is the Naval Warfare Center, China Lake Pump-Action Grenade Launcher.  The date listed for this is "1968", so I am not sure if the players will have access to one.  The breech opening appears to be sized at 4", just long enough for HE, but not for any smoke or illum rounds.  Plenty long for the M576 Buck-Shot round though.