Moly Shooters Beware

[rcw3]

Over the years I have tried moly bullets, but was never particularly taken by them for a variety of reasons. Recently I became aware of something which has convinced me that moly bullets can present an unexpected issue that can definitely cause an accuracy problem. I do a lot of 6mm shooting,6mmAR, 6x47 Lapua, 6mm/22-250, 6XC, 243 Win, etc.) and almost without exception the reamer specs for a 6mm freebore in these cartridges is right around .2435" in diameter. What I noticed is that factory coated moly bullets typically vary in diameter because of the moly and wax coating on the outside of the bullets. This coating, on top of a plain bullet that would otherwise be .243" in diameter, can make the bullet measure anywhere between approximately .2432" to .2436" in diameter at the bearing surface. The problem becomes when you try to push a bullet that has moly and wax on it and measures .2434" to .2436" down a freebore that is .2435" in diameter, it does not load through the freebore easily,extremely hard in some cases) and this can lead to seating problems with the bullet and/or the pushing back of some of the bullets into the case as the rounds are loaded into the chamber. I measured factory coated moly bullets,Sierra, Hornady, Berger, Norma, etc.) and it's an across the board phenomenon that they all vary somewhat in diameter because of the moly and wax coating on them.

This may not be a problem if you have a loose or sloppy free bore dimension in your chamber, but if you have a match chamber that's true to the reamer drawing, it can definitely be an issue, and something you have no control over, unless you are going to sit there and measure every moly bullet you intend to shoot to sort out those that might not readily load through your freebore.

Robert Whitley