In this case yes about both the solid pin and the investment.
I'm not an engimanear or nothing Fancy like that, but I seem to recall reading or hearing that a tube sometimes has more strength than a solid in some applications. And the other reason I believe they went (and when I say they I mean every firearm mfg with the possible exception or the custom builders,) to the roll pin was because it came in one width and then customer doing his own Gunsmithing didn't have to worry about which end of the pin went in first and from which side.
If anyone doesn't know this bit most solid pins are tapered but because they are so small and the taper is on scale to the size of the pin, that they can only (technically) be put in one way and no one had to worry about it after than because of certain friction and physics mumbo jumbo kept them there. But folks like y'all and me we didn't know this and when they wouldn't go in (the pins I mean) we got out the High precision 3 lb sledge and tapped the pin into the hole. Which caused no end of problems the next time they tried to take the weapon apart. So someone came up with the roll pin. stick that baby in either side, use a pin punch of the ends to spread them out and bingo not so many problems any more.
Gee was that a fun class or what? Ya ya I don't want to hear any "or whats" out of anyone.