Did you mean a "J" frame hammer mainspring strut or as S&W prefers to call it.. a Mainspring stirrup?
So, the poster was correct, it IS a stirrup, according to S&W.
Usually the stirrup doesn't require smoothing, and polishing it to a mirror shine does nothing for it.
If it is rough for some reason, like being scarred by improper disassembly attempts, it can be smoothed up with fine grit wet or dry sand cloth.
One way of doing this is to chuck the bottom end in a drill press or a securely held hand drill and using wet or dry sand cloth in a "shoe shine" way on the rough area.
Another it to simply fold some fine sand cloth over the round strut and running the stirrup up and down the sand cloth to smooth it.
If the stirrup is heavily scarred up you can use a fine stone to smooth it out, but if it's very rough you'd be better off to just buy a new part.
Brownell's sell "J" frame stirrups for almost all the "J" frame models.
These will be brand new parts, not used....
Click on your model and click on the blue "Find all available SKU's" tab"
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