Originally Posted by BELT_FED

threading when its done right takes a bit of time... the barrel has to be indicated in using a jig to center it on the bore of the rifle not the o.d... it usually takes me longer to setup a barrel for threading then it actually takes me to thread it... the only reason i can think of that they would need your flash hider is to index it or if you dont wanna use a washer, he would need it to make the threads to the right deapth(some are more shallow than others) or maybe he just wants it to protect your threads during shippment... all flashiders/comps for the ar-15 platform are 1/2-28 threads and suppressors for the most part in this cal. are the same or use some kind of adaptor(yhm phantom 556)
hope this helps