Ruger will not fix tight throats. I've tried. They will shoot it, even with poor accuracy and say it's good.
These guys will make what you need.
https://pacifictoolandgauge.com/512-...gauges-cutters
Or Manson has a .32 in their product catalog.
https://mansonreamers.files.wordpres...-catalog-1.pdf
My advise is to get the pilot pack and some Drill Do from Brownells. They don't say what the final diameter is so call them first.