To ease my concerns with the primer inside the W-816 tubes, I dropped a string thru the tube and tied it to a wad of shop towel. Took a rattle can and saturated the towel, then pulled it thru the tube. Inspected with a penlight and appears that everything is covered. To complete the end pieces, I sprayed a generous coat of primer in the end of the W-816 and quickly inserted the VA-111. Dipped each MSP-42 blind rivet in primer and popped them in.