what kind of slide and barrel?
shotgun slides for pumps and barrels can be mailed/shipped as far as i know. as long as the barrel is a minimum length of 18.5" i had 2 shotgun barrels that i won on ebay. both were shipped directly to me. 1 was 20" the other was 28". rifle barrels as far as federal law must be a min. of 20" long. and shotgun barrels must be 18.5" long,unless you pay the $200.00 tax and it is registered as a short barrel rifle or short barreled shotgun.