"Bolt sleeve - Shockers originally came with black-anodized aluminum sleeves but SP switched to white delrin versions around August 2003 because the delrin material is more inexpensive. The bolt sleeve was then switched back to the black aluminum ones in late 2004, because they tend to hold tolerances better than the delrin versions (also less interactive with temperature changes)."
BUT...the bolt could be either stock or HE, if it has a 15/90 o-ring on the front of the bolt stopping the can from sliding off its HE, also the can should have a removable front face.