I have several shot guns that use Tru-choke thin wall chokes and recently ordered the reamer and tap to install these in a double barrel shotgun. I read their instructions. Reaming the barrels went fine. I tapped the barrels and that went ok. I tried to install a choke and it turned a quarter turn and stopped. I was looking at the tap and it stated that it is a .775 44 tpi 2 start tap. I think they sent me the wrong tap since the choke tube uses a single thread. the retailer is telling me that the tap is correct. I talked to a machinist that told me a 44 tpi 2 start tap uses to 22 tpi threads for a total of 44 tpi which means the choke is not compatible. I would greatly appreciate feed back to to help clarify this information. In the mean time I have a ruined shotgun. Thanks.