Hey ! This didn't work with gameplay mods making use of the UNDROPPABLE and UNTOSSABLE states for weapons and items. I created a small fix (simply a loop that goes through all the player's inventory and remove the items before clearing it like you used to to make sure ammos get removed as well). You can upload it here : https://www.mediafire.com/file/vq55pnyc5iawazw/pistolstart.rar/file
Just so you know I am uploading that as well on the ZDoom forums, I think having it on either ZDoom or DoomWorld would give it more visibility. However if you want me to take it down, or recover ownership of the forum topic, tell me. I'll warn the mods and they'll let you edit the OP so you get it back (at least I think that's how it's done, in all cases, tell me and I'll give it back to you, this is 100% your mod).
Have a good day :)