Interesting video , so full of bad information . 1 . There is NO barrel extension on the barrel , it is just MADE larger at the rear , it threads in like normal . The difference is the bolt locks into the barrel itself , not the receiver . 2. It is a normal style T-99 bolt , the handle is NOT cast and welded . 3. The extractor is steel , NOT cast . 4. The few carbine were made to salvage damaged barrels , had nothing to do with making more from blanks. 5. Training rifles were used by schools , they were NOT bought by parents for home use . 6. The navy had no rifle arsenals , all Military arsenals are named and known .