That's odd. Have you removed the carrier from the action to see if a cartridge will drop into it then? If so, then it's the alignment of the carrier with the magazine that's the problem. Dirt or debris could cause that by preventing it from setting down as low as it is supposed to, but you'll have to look and see what stops it and where. It's not uncommon to find lead or even occasional brass shavings in rimfires. If the cartridge fit is tight, then the carrier's picked up a burr of its own and you need to identify it and file or wet/dry it off. A little Magic Marker on the cartridge case will show where it rubs.
All the rimfires have a maximum case head diameter of 0.278". Chamber rim recesses that set the headspace have a minimum of 0.288" and a maximum of 0.290". A 9/32 drill is 0.2813", so I'd expect its shank to be able to drop into the carrier freely or its cutting end to be able to turn freely. If the shank is a little undersize (not uncommon) then try a letter L drill (0.290") with an equally undersize shank. If it's tight, perhaps a little lapping compound and some back and forth with the drill bit shank would fix that for you.
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Last edited by Unclenick; May 4, 2011 at 10:40 AM.