I am flat out DESPERATE for ammunition. I found Aguila Super Colibri's in stock at a good price for a brick of 500. However it says not for use in Semi-Auto rifles. These things have a 20 grain bullet that fires at 500 fps with just the primer, no powder. I understand they don't produce the recoil to push the bolt back and cycle another round, but for the "no rifle" part, supposedly some long barrels have enough friction to slow the bullet down to stop it completely, and when the next round is fired, it will be catastrophic. Anyone confirm this?