The SP101 is noticeably smaller and lighter, I’d suggest a run to a gun store just to hold them. Both are from the days when Ruger built ‘em heavy, both grips are nice and both triggers are just ok. Out of the box, GP’s might be slightly nicer, but there are spring kits out there that smooth it out without light striking. Or, it coild just be it is bigger and thus you get better leverage on the GP.
Now, if you can find an old Security Six, you’ve found the best carrying gun Ruger ever built.
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