The Barnes site says the TSX, TTSX and LRX are 100% copper, the same as the original X's--not a different alloy.
That addresses my original confusion - how can 100% copper be an alloy?
Their Safety Data Sheet lists the following: Lead 2-3% Zinc 35-36% Copper 61-62% Don't know if this has changed but the old X bullets looked different, more like copper pipe. The newer bullets look more like gilding metal.
