I need an advice

So I’ve been trying to model a bolt action rifle for a long time, and had different kind of issues when I got to the point where I need to model the grip of the rifle. I don’t know what is the best way to make this curved grip that connects to stock (which I’m not sure how to make too). I tried making block model, then with Sundivision Surface modifier make it smooth, but I had problems with shading later, what’s more when I apply this modifier and edit my model, Blender gets really laggy and my CPU loads on nearly 100% (although I don’t have huge amount of verticies, and my CPU is not that weak - Ryzen 5 5600X). So please, tell me the proper way of making the grip!
here is the reference I use

I would model it as a rectangle add a solidify modifier, then bevel the corners (CTRL+B), apply the solidify modifier and then adjust the upper corners. Bevel is magic.



Rectangle with solidify:

Do not copy the solidify thickness this is NOT modeled to scale!

Beveled rectangle with solidify:

As with adding loop cuts, just scroll your mouse wheel up to determine the resolution. If you plan to subdivide your model, stick to the lower side.

Maybe look for other 3d rifle models to see how they did it.

Look at this: