BudsGunShop.com - grip frame M66

Hi Chris, It is Square K Frame and you can switch out the grips.

Chris, I have come across both styles at various sources so "when in doubt" go straight to the source. Smith and Wesson Product Information/Customer Service at 1-800-331-0852 : Mon-Fri 8:00AM-8:00PM Eastern Time (S&W Live Chat Mon-Fri 9am-5pm EST) at the following link : smith-wesson.com/customer-service/contact-us

I came by my answer by looking up the grips for the M66 here are the specs on the Hogue M66 grips HOGUE Rubber GRIP 19000
fits S&W K or L Round Butt Rubber Monogrip
Fits: Models 10, 12, 13, 19, 64, 65, 66, 547, 581, 586, 617, 681, 686 and 696.
W K and L

yes you can use them they will fit and The M66 is a Round frame

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