The "issue" with the Roberts is not 1/10" twist, it's the throat lengths are all over the place.
I have a 1983 mfg E.R.Shaw on a 1939 LaCorouna M98 Mauser action. I've shot 5-shot 0.6" groups at 100yds with Hornady 75gr HP at 3,500fps.
Likewise, I've shot 117 and 120gr Sierra GameKings into some tiny groups over 4350's (IMR, H, ACC) and 4831's (same, to include RL22).
By request, my rifle has the "so called" 3" chamber, throat. Besides, it's a high quality custom barrel.
I had a Ruger M77MKII as well. It had a much shorter throat, and didn't shoot well, PERIOD!!!
Only load it shot "ok" with was an ancient classic load of 38.0gr IMR3031 under the Hornady 100gr Soft Point. It had a short throat, but the real problem was a crummy barrel.
I'm not a Ruger hater. I've got a few, but many more have passed through my hands, but weren't "keepers".
Contrary to many opinions to the contrary, Remington has made some outstanding bullets, the old round nose Corlokts among those.
The current rage and fad are the 6.5's. I've got a Remington M7 in .260. Decent rifle/cartridge but re-invented the .257 Roberts. Out to 400yds, I can't detect a difference, however, my M7 has a 1/10" barrel that actually measures 1/11". It "GAGS" on any plastic tipped bullet over 123gr. 129gr SST's shoot 4"3-shot groups at 100yds. 140gr SST's won't hit the berm!!! However, it will shoot .7" 5-shot groups with a Sierra 160gr RN.
If your "Bob" won't shoot a 110-120gr bullet, it's more likely the bullets, or the barrel doesn't like that bullet design.
I've had spotty luck with various plastic tipped bullets. If it won't shoot well with a Sierra 117gr ProHunter over 42.0gr IMR4350, then I'll concede you have a barrel problem. In that case I'd measure the twist. I'd bet its 1/12" or such.
I've had spotty luck with Hornady bullets. More so the plastic tip variety, particularly in .25caliber. If I were to shoot factory ammo, I'd first try the Hornady WhiteTail Classic with 117gr BTSPT Interlok. (Unfortunately it has the picture of a "has been" rock star on the box)... Secondly, I try the Federal Premium 117gr GameKing, followed by the 120gr Partitions. If you have an elk license, use the latter. However, I prefer the various 100gr bullets for deer. Particularly the 100gr Sierra's. I've got a lifetime supply of Hornady 100gr Spt "blems". They'll work for any use applicable to a Roberts.