XAK Mainspring for AK platforms. A new mainspring is a tri-twist, music wire AK mainspring that provides a 2+ pound pull weight, and a hard, positive reset on our popular XAK series triggers. The XAK Mainspring is compatible with the XAK line of triggers, as well as other stock and aftermarket AK fire controls. NOTE: Pull weight and feel may vary from receiver-to-receiver, and trigger-to-trigger as there is no "mil-spec" standard for all AK platforms.