Increasing the settings in
weapons.xtbl will conflict with settings in
weapon_upgrades.xtbl. Notebly, increasing damage of rifle in ONLY
weapons.xtbl will make the upgrades offset. If one increases the damage for rifle in
weapons.xtbl, it would be prudent to increase rifle damage upgrades in
weapon_upgrades.xtbl, in a ratio mirroring the original values. For example, increase the "Rifle-Gang" in
weapons.xtbl by 100% and then hunt down the damage upgrade for "Rifle-Gang" in
weapon_upgrades.xtbl and increase each step by 100%. Otherwise, your un-upgraded "Rifle-Gang" ends up being more powerful than an upgraded "Rifle-Gang". I hope that I said this clearly enough to understand.
If you want to twiddle with settings, I recommend using
SRTTxtblEditor (<--clickable link), and making a backup as you twiddle until you have what you like. If you feel frisky, you can use Notepad++ to ADD flags and other properties. I recommend saving .xtbl files with SRTTxtblEditor before attempting ADDING or REPLACING anything with Notepad++, just to keep the formats readable for yourself. The original format puts each weapon in ONE LINE, making quite difficult to read and comprehend. If, however you save the file with SRTTxtblEditor first, then open with Notepad++, the format becomes MUCH more readable.
Good Luck!