These types of chokes were cut with special made reamers. Anything is possible today with modern technology. You could have a reamer made to any shape you desire. Because of the limited usefulness of such a tool it would not be cost effective unless you planned on cutting a bunch of chokes to this particular shape. A whole bunch of work and cost for very little gained over a choke with a parallel section in my view.


Firearms imports, consignments


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