It's been a good while back, I bought some converted LC brass, I believe from CASTING MACHINE here on the forum. Tried loading some coated cast bullets I had puchased. Loaded rounds will not chamber in my Howa bolt action rifle. So, I thought being the coated bullets are oversize, I will load a .308 jacketed Sierra 220 RN Soft Point. Same results. A friend had given me 7 rounds of factory 300 BO Subsonic ammo, so I tried one of those. It chambered fine. Measured the case necks. My hand loads necks are several thousandths bigger in diameter than the factory load. So, I bought a .308 inside neck reamer for my Forster case trimmer. A couple days ago I finally got around to trying it. Reamed a case, which took way longer than I expected, stuck a Sierra bullet in the neck and it fell right through. Ran the case into my Redding sizer die and tried again. Same result. So I took one of mu very oversize coated bullets and ran it though a Lee .309 sizer die. Still loose in the neck. Then I tried a commercial cast 245 coated boolit from another source that measures about .310". It would not start into the neck without belling. I use a Lee universal neck expander to do this. After belling the mouth, this bullet seated fine, with good neck tension. This round chambered and fired just fine. The way I see it, the only way I can use this 500 piece bag of brass is to outside ream the necks. This would be a huge job. So I called Starline to order some factory brass. They are out and don't expect to have any for 10-12 weeks. Checked Midway and they don't have any brand of 300 BO brass. Have any of you 300BO shooters run across this problem with the necks being too thick?