1. Do you have an N (Large) Frame Revolver?
From the way the grips look and feel, K/L and N frames are very close in size and fit. The N frame is more solidly built elsewhere for magnum calibers. Therefore, the larger magnum calibers are generally N Frame. The best way tell the difference between K and N is the model numbers.
K Frame Model numbers: 10 to 19, 547, 586, 581, 617, 686, 696, 986, 55, 64, 67, 48
N Frame Model numbers: 23, 25, 27, 28, 29, 625, 629, 627, 327, 325, 329, M&P R8, 57, 59, 624, 625, 626, 627, 629, Magna Classic
2. Do you have a Round Butt Frame?
Understanding Conversion Grips
A Conversion grip changes a Round Butt Frame grip to look and feel like a Square Butt Frame grip. It extends support at the heel of the hand for additional control and recoil absorption. A Round Butt Conversion grip will not fit a Square Butt frame and a Square Butt grip leaves a huge gap on a Round Butt Revolver.