Originally Posted by thumbs
I just want to make sure I understand what your saying. The Lee full length die won't work because my chamber is really just a touch under spec, to tight and the original firing of the Lake City brass was in an chamber that was a bit oversize or over spec. Now the RCBS will take the entire oversize Lake City case and make it smaller in diameter that will allow the round to enter the chamber. Is that correct???
It sounds like this is a common problem with once fired milspec brass in a civilian AR since RCBS went to the trouble to make an undersize die set.
So the fix is the RCBS two die set right?
The issue is not that you have a tight chamber. The issue is that the military chambers the brass was fired in tend to be more generous (especially around the case head) for reliability reasons.
Yes, this is a common problem when reloading with military brass. I ran into the same problem loading 7.62 NATO LC brass (which is even worse than 5.56 in terms of loose chambers). All you really need is the small base full length sizer die:
RCBS Small Base Sizer Die 223 Remington
The good news is that you should only have to do this the first time you load milsurp brass. With my formerly machine gun fired 7.62 brass, I found that re-sizing with conventional dies and then following that with re-sizing through the small base die worked best. Some cases required A LOT of force to small base re-size on a single stage press. Sizing in two stages made things go a lot more smoothly. I also found that it worked better to do the primer pocket swaging and small base resizing as separate steps from the rest of the reloading process. Once the brass was fully prepped, it could then be used in the progressive press and loaded normally.