Sig Sauer MCX Opearting Spring Assembly Kit

By Anonymous

I used this kit to upgrade my Gen 2 bolt carrier group with the plastic spring retainer to the Virtus version that has the metal spring retainer that is pinned in place. Note that the operating rods in this kit are ever-so-slightly different than the ones that are used with the plastic spring retainer, so you will need to use the rods from this kit as well if you are doing the upgrade (the reduced profile where the rods click into the spring retainer is slightly longer on these new rods to fit the longer section in the spring retainer that is necessary to allow room for the roll pins). I don't know if you must use the new springs or not - I don't really notice any difference in them - but I did anyway. As for value - given the price Sig wants for a new complete BCG, this was an inexpensive way to upgrade an old BCG to the most current (and potentially more robust) version.