actually a good idea hell if I could id go one step father than this. So something like this as a mini arsenal mod.
9mm side arms
1: Glock 17 changed to a 15 round Beretta M9 for BM security and HECU marines
2: Move the Glock 17 to the cut suppressed Glock slot and add its suppressor which would be easy as the code for it is still in the game and it still works just doesn't have a inventory HUD icon. "would be obtained from assassins and black ops"
Hand cannon side arms
1: Change the .357 Magnum to a .44 Magnum counter part like in the beta of HL1
2: add the 8 shot .44 Magnum Desert Eagle from OP4 with laser sight for HECU Marines
1: SPAS-12 changed to a pump action only 8 shot Mossberg M&P 500 for both BM security and HECU Marines. "Secondary double shot would be replaced with the revolvers ADS function"
2: Add the stock less semi auto SPAS-12 with a suppressor to the black ops. "Secondary double shot used here could be a semi auto double tap with exaggerated recoil because it has no stock and is a 12 gauge it IS going to kick like a mule"
primary assault weapons
1: Change the MP5 to the integrally suppressed 9x19mm MP5A3 SD M203 and give it to Black ops and maybe also place them around the dead HEV scientists in Xen.
2: Add the cut 5.56x45mm M4A1 M203 for the HECU Marines and maybe even code the Marines to use its 3 round burst function while the player would use it in full auto.
this would greatly mitigate the HECU Marines almost aimbot like accuracy while the black ops guys would fire full auto and be much more dangerous up close to the player.
Id also maybe add the 5.56x45mm M249 Para as a special weapon for HECU marines with a 200 round box / belt as easter egg nod to the old cut HL1 minigun
Also as for the black Ops Id make the vanilla HECU marines with NV googles the black ops as the skins for that already exist and as such all you would have to do is code them to be hostile to other HECU marines as well.