I posted this in the RPR thread a while back but haven't got any replies yet. I'm hoping someone can give me an idea to fix my problem. I have a RPR in 308 win. and have recently purchased 500 rounds of plastic training ammo that the german military uses for practice. It's NATO 7.62 x 51, runs a 10 grain plastic projectile at around 4500 fps, and has a plastic case except for the very rear of the cartridge where the rim and primer are which is brass. It's pretty cool stuff with a max effective range of 100-150 yards. I think it's going to work great on rodents. The problem is that the fired casing won't extract, as in the extractor won't grab the rim. The fired casing is loose in the chamber and would probably fall out if the bolt was open and a guy hit the stock with his palm, of course I don't want to do that nor do I want to run a cleaning rod backwards down the barrel after every shot. I measured the rim of the cartridge and it's about 10 thousands smaller than 308 win. Any thoughts ???