I've been experimenting with coated cast bullets from Missouri Bullets in my Marlin 336 in .35 Remington. I'm working on developing plinking loads using .38/.357 bullets over Unique and possibly HP-38. So far I like the "Ranger" bullet best, over 10 gr of Unique (normal warnings that this is my load and you use it at your risk and should follow all reloading safety precautions).
One issue I didn't think about, but should have, is neck tension. Since .35 Rem jacketed bullets are .358', I had several instances where my .358" coated bullets were pushing right down into the case with finger pressure. I had full length resized the cases and then "flared" them with a Lyman M-die for .35 Rem. Once I figured out what the problem was, I chucked my extra decapper-neck sizer into the lathe and filed off about .002". I also did the same with the plug in the M-die. Now I get good resistance when using the M-die and excellent resistance when seating the bullet. My next issue is my Lee neck sizing die. I want to make the same reduction on a spare mandrel. I plan to call and see if I can special order an undersized mandrel, since they catalog them for several calibers before I try to do it myself. Has anyone tried to order one?
I've been getting my best groups with 10 gr of Unique, slightly better than with 9 gr. With 11 gr, my group opened up quite a bit. The GMDR report mentioned that they found that groups "blew up" with micro-groove barrels at a certain critical velocity (in the 30-30 it seemed to be about 1350 fps but they weren't using a micro-groove barrel in their .35 Rem test rifle). Mine has the micro-groove barrel, and although I haven't had the chance to chrony these loads the Lyman data would indicate I'm getting into that ballpark. Again, can anyone share their experience?