FWIW, I went ahead and tested the several commercial swaged bullets I had on hand.
Speer 38 Cal (.358) Lead SWC, 158 gr. (#4624): BHN 5.5-6
Hornady 38 Cal (.358) Lead SWC/HP 158 gr. (#3589): BHN 5.5-6
Rim Rock 38 Cal (.358) Lead SWC/HP w/GC 158 gr. (the bullet Buffalo Bore uses in their 20A load): BHN 5.2
Speer 44 Cal (.430) Lead SWC 240 gr. (#4660): BHN 7.5
The Speer 44 Cal came in slightly higher than I expected (I see no reason Speer would use a different lead composition in their 44 line than their 38 line). The others are in line with my expectations. I may re-run the Hornady test the next time I have the stuff out.
The Rim Rock bullets are fresh. The Speer and Hornady bullets are all quite old (probably north of 30 years). That shouldn't matter... cast bullets will harden a couple BHN points as they age (with most of that happening in the first few months). Swaged bullets, to my knowledge, do not.
The bottom line is that commercially swaged bullets are usually going to be very soft - approaching pure lead (which has a BHN of 5).
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