No, that would be perfectly legal as far as I know, I just did not want to spend the dough for something I would not use more than once. The only problem I can foresee aside from the $ would be the tuning of the weapon. The process for tuning the gun involves firing single rounds and evaluating if the hammer and breech block springs need to be shortened or not. I would think the longer barrel would generate some greater blow back forces (could be wrong here) and I would have to have two sets of springs, one for the 16" barrel and one for the shorter one.

DOes that sound right?