Xausa: The roll-crimped area is not just to keep the slug in the hull. It has the same significance as any other crimp, and we know that a weak crimp results in less velocity. It holds it for that micro-second while the proper pressure builds. I also don't like the thought of unattached things going down the barrel, but that's just my opinion.
If you have access to another 70mm chambered gun, fire one and then measure the hull. Roll crimps are not as long as fold crimps. You might be OK, but I would measure to be sure. It is possible to trim cases and then roll crimp your own. This is probably the best bet, as you can then also adjust the pressure and velocity of the projectile. MEC, for example, makes a "short kit" for their loaders. Hope you enjoy your drilling! Steve
