In recent times the big variations all originate from what product with the 590 you buy. Even though the armed forces 590s use a metal cause device, the 590s you see in gun shops very likely have polymer triggers and induce guards. The 590A1 is built into the MIL-SPEC along https://legendgunshop.com/product/browning-x-bolt-…range-24-6-5-prc/