I have a 300 wsm model 16 (Stainless Steel) that is a switch barrel gun, switching from 300 wsm to 270 wsm. I have had a couple primer failures which has etched my bolt face and I would like to get a new bolt head.The problem is mine is a push feed not control feed. All the heads I see on midway are control with the standing ejectors. Can anybody tell me what head I need (part#) and where to get it. Thank you for you help.