Gents:
For what its worth, the ones from tacshot are US produced, 6 position comercial tubes. They are a good unit, as these are the same stock that many US makers rebrand to their own.
Further, for what worth, in my expericned 4 possition are usually comcercial. However the only true way to know it to mic it.
If memory serves, Milspec will be very close to 1.14 with comercail being very clost to 1.17.
Do not forget guys, just because its comercial, does not mean its bad stock.
The general rule of thumb is the comercial stock a generally slightly longer, as one of you have already noted.
Just my 2 cents worth.
regards
AbH