: No, no, no, no, no! I talking about the graphic that you see in-game on the
: ground. The actual gun! not the weapons-in-hand graphics.
That graphic is straight from the Shapes-file. Paste something else over it in the Shapes-file at the correct frame and you changed it.
Changing this graphic in only the Physics file is not possible (as can be done with monster/scenery-sequences), there is no field to change the value of the weapon. (The same for power-ups and vision-enhancements)
It is possible however with Aleph-One and MML-scripting. This can overrule the standard with values you like. (And while you're at it, you can change anything in the HUD-display to represent your new weapon, including ammo and ammo-behaviour)
I guess FUX can also do this, but for A-1 I have a (crappy) sample at the following link (1.8 mb)
SMG and AR are replaced by the counterparts of Halo; the S2AM and the MA5B_AR. (with 3d models, but instead of these ramhoggers you can also replace them with elegant 2d-sprites)