Put a Tandemcross sear and disconnector in my MK IV couple months ago. Worth the effort now have about a 2.5# trigger. Was a kind of a bugger to get in, but after doing it once I think I could easily do it again. Was about $40 upgrade.

I'm just a stock kind of guy...except for my DeadAir Mask suppressor.

I can't get over how much EASIER it is to clean these Mark IVs!!!

The Tandemcross trigger upgrade is almost a must. Worlds different from the stock trigger.