The No.3 is a few ounces ligher, according to the books, but it FEELS much lighter than the No.1.
The No.3 has a straight grip stock, and the finger lever forms the "pistol grip". Also has a barrel band (why I don't know, other than cosmetic). Also came with a steel buttplate.
I have a good ventilated recoil pad on my ,45-70, and with the "standard" 400gr slugs at black powder speeds, the recoil is not bad. Also will put three shots in two holes at 50yds with a 2.5x post scope. so, about 2 moa with that load. I have shot 350gr Hornady @ 2200fps, and let me tell you THAT is recoil.
Also have No.3s in .22 Hornet and .30-40 Krag. Great little rifles, I actually prefer them to the No.1 except for (a) being out of production, and (b) limited caliber choice (see (a) ).
Consider them stalking rifles, short, light, handy, and quite accurate enough for game shooting. Not a bench gun, NOT a REPEATER, so group size is kind of ..why?
I have sold off my Marlin, and my Siamese Mauser .45-70, but have kept the sweet little Ruger. Another reason I like the No.3 is they were made back during the era when gun owners were still trusted to adjust their own triggers. The No.3 has a couple of allen screws, and if it doesn't have one when you get it, its only a few minutes work to give it a sweet crisp trigger pull.