It seems like older guns had factory grips that were less than desirable.
Are you kidding? Have you priced an original set of Service grips recently? Not desirable? Hah!
Neither revolver is pleasant to shoot with their factory grips. Are they just for style?
Style??? No, they are what the factory was making at the time.
First off, let's get a few definitions agreed on.
These are hard rubber Service Grips. Grips like these were on the first K frame Hand Ejectors at the beginning of the 20th Century and continued to be issued up until around 1940. This particular M&P was made in 1939.
These are wooden Service Grips on an N frame Triple Lock. They were called Service grips because thousands of policemen and servicemen learned to shoot revolvers with grips like these.
Do I shoot these old revolvers with these old grips? Absolutely! I wouldn't dream of bowdlerizing these fine old revolvers with replacement grips. My heartbeat quickens when I see a nice old Hand Ejector with its original Service grips still on it, my heart sinks when I see some off brand replacement grips on an old Hand Ejector.
These are Magna grips. Elmer Kieth claimed credit for talking Douglas Wesson into creating them, to lessen the effect of recoil with the older Service grips. Magna grips first showed up around 1950. Personally I find Magna grips very comfortable when shooting a 38 Special like this Model 14-3.
When I bought this Model 19-3 in 1975, these grips were known as Oversized Target grips. I have always found them very comfortable when firing a light revolver like this with factory 357 Magnum ammunition.
But when firing factory 357 Magnum through a heavier N frame, like this Model 28, I have always found the Magna grips to be perfectly adequate.
This 44 Hand Ejector, 4th Model is very comfortable to shoot with its original Magna Grips.
On the Colt side, I always prefer original grips, particularly hard rubber like on this Army Special from the 1920s, whenever I find them.
So, keep your rubber grips, use them all you like, but I prefer the original grips that came on any revolver every time over replacement grips.