Originally Posted by
MK18Pilot
While I can understand plating the bolt, I can't understand plating the carrier. The carrier rides on four thin rails and the bolt pocket is already chrome lined. Spot application of plating to the rails would be difficult and cost prohibitive.
Contrary to a previous post in the thread, manganese phosphate is an excellent coating. It has excellent corrosion resistance and provides superior lubrication for metal to metal contact. It is a sacrificial finish and has excellent break-in properties and reduces wear on moving surfaces. It's highly absorptive coating retains oils, rust preventives and lubricants.
The nickel based coatings hold very little lubricant as their surface matrix is not course enough and lubricant easily flung off of coated parts.