Its true, I think Elmer would love some of the guns & calibers we have today, although I don't think the quality of guns is better for the most part, now they are stronger, longer lasting guns but the fit & finish of the early S&W's & Rugers will never be matched except by the custom guys.
The biggest overall improvement has to be the big, heavy slugs available including some very top quality jacketed slugs, when I started back in the sixties the choice of jacketed slugs was pretty narrow. The old Speer half jacketed slugs wouldn't do much unless you really stoked them up with heavy charges of 2400, but for the most part they just acted like a solid.
I never use jacketed slugs anymore but would be perfectly happy with a Nosler or Belt Mountain Punch Bullet for most game shooting, when the animal gets elk size or bigger nothing will perform like a good heavy wide cast slug. They drive straight & deep & can penetrate the big bones.
No bullet of any kind will make up for shot placement, if you get that & penetration you're on the right track.

Dick