They'd be dead easy to make. Oil a lead bullet, cover it with low melting point hot melt glue, let the glue harden, pull the bullet out, oil the inside, squirt silicone caulk inside, and peel/melt the glue off when the silicone cures. Then pry the lead bullet out of a cartridge, and shoehorn the rubber one in.
The difficult part will be keeping the rubber from getting pushed into the cartridge in the magazine. I recommend bolt action to avoid this.
It would be easier to put a rubber slug in a shotgun shell.
[–] littul_kitton ago
They'd be dead easy to make. Oil a lead bullet, cover it with low melting point hot melt glue, let the glue harden, pull the bullet out, oil the inside, squirt silicone caulk inside, and peel/melt the glue off when the silicone cures. Then pry the lead bullet out of a cartridge, and shoehorn the rubber one in.
The difficult part will be keeping the rubber from getting pushed into the cartridge in the magazine. I recommend bolt action to avoid this.
It would be easier to put a rubber slug in a shotgun shell.