About four months ago, I purchased s/n K 6428 and it had later checkered target grips that do not fit real well.

I wanted to add early standard diamond grips and so far I have chipped two beautiful sets of them. After chipping the first set, I tried to be very careful but chipped another set today. This is getting expensive, I need help!

Do the early K's have different shaped grips?

Will only target grips fit?

Thanks, AL in MN

Targets weren't available in the timeframe of that gun,only magnas.A post war square butt K frame should be pretty much the same to present.
If you're forcing,sure that the new grips are K frame,something is wrong.Are the grips chipping in the same place? Where?

The grips are chipping in front of the medallion closest to the trigger guard where the curve of the front of the backstrap meets. Both sets seem to bind there and on the second set, I carefully rocked them in until they got stuck.

Sir.
The reason the early K magna grips have a serial number on the right grip is because they were hand fitted. Yes, there may be a difference in the frames of the early guns.
Buy another set and have a real stock fitter, wood worker, fit them to the frame. That is how S&W did it.
Bill@Yuma

Not uncommon with the K frames. I bought a "pre chipped" set from a member here. He did point out the damage and repair.

I did properly fit, fix, and refinish so the damage is now undetectable.