Nill Grip screw size

I have Nill anatomic grips for S&W K frame that I lost a screw for, which is holding two halfs.  Other SW Nill grip screw fits (from older grip model), as well as 1911 Nill grip screw fits (current grip model), making me think their diameter and thread pitch are a constant across grips.  Does anyone happen to know or can measure diameter and pitch, so I can find similar screw online?  I emailed Mactecsales as well and waiting for their response.  Will post if and what they tell me. 
Thanks!

These folks are always responsive and customer oriented. 

"The mounting screw for the Nill S&W grips is a M3 x 28 mm.  We have it in stock but it would be much cheaper if you could find one in a local hardware store.  https://www.mactecsales.com/ZSB3028_p/zsb3028.htm

Regards,
MacTec"