Could've sworn the pre-order listing said "...or you can ship your take-off barrel to us and we can install them for an additional fee.". Bit more of a pain to ship the entire rifle but I suppose I understand the desire to test fire from a shop perspective.
If I were to pull off my current barrel and only send the receivers/stock/BCG/recoil spring with a handguard/screws and the naked take-off barrel, is that viable for you guys? I could even include the extra gas regulator retention parts I had ordered to put into your gas block. Just to cut down on overall shipping size/weight.
If that's a "no" and you still want the current install barrel with it, I'd probably also want to buy a second gas block and have both my barrels be fitted with a Dlask gas block while the rifle is there.