T/C's use different nipple threads than foreign rifles, and while the foreign ones will seem to screw in, they will not be tight enough
That's a fact. The TC thread size is 1/4 x 28. A metric nipple that's M6X75 will seem to fit but must not be used even though it will go in the 1/4 x 28 nipple seat and tighten down. If you're not sure the threads are right on a nipple, screwit infinger tight, then back it out 1/4 turnand try to wiggle it side to side. If you get any wiggle it's the wrong thread.