If you are reaching the velocities as you stated, then you must have a "fast" barrel, or a longer barrel than is commonly seen with the 'bob. Most of the listed velocities are with 22-24" barrels in the manuals I have.
Not at all,and this is a common misconception when it comes to the Roberts..
My experience with the cartridge goes back to the 70's and I have had several;firnds have added to the mix with a few others.My notes from that far back are long gone,but some I remember were a pre 64M70 with 24" barrel,a Ruger M77 with 22" barrel, a custom Mauser with 24" barrel,and my old FW PF with 22" tube.
All these rifles would variously give 3050 to 3200 with a 100 gr bullet,2900-2950 with 120's,and 3000-3050 with the 115 gr from these 22"-24" tubes.FWIW,87's could be easily loaded in excess of 3300.
The Roberts is one of those cartridges (like the 7x57 and 280 Remington), whose velocities can be improved by judicious handloading,and due to the fact that factory and manual velocities were held to low levels,and for no good apparent reason since it was always chambered in good strong bolt actions...whatever...I suspect it dates back to the early origins of the Roberts,and the fact that the crummy bullets available back then shot better at more sedate velocities,and maybe concerns about the M96 Mausers and other surplus actions that got chambered for the cartridges,as they were perceived to be "weaker" actions.
Fact of the matter is that the above velocities are easily attained with modern powders in bolt action rifles and 22-24" barrels.That old FW I had gave right at 3200 with the 100 gr Nosler Partition, and consistently showed 2950 with the 120.I used that rifle with the 100 gr Partition to take my largest pronghorn at close to 400 yards.
I'll also note that case life was always good with these heavier loads;no primer popping or other difficulties ever encountered.
I never used the 115 very much but that Ruger(which belonged to the wife of a friend),gave 3000-3050 with the 115 Partition and she used it on black bear, mule deer,and pronghorn antelope.Barrel was a 22" factory job.
If these velocities seem eerily close to what a 25/06 delivers from factory ammo,that's because they are.....one of the reasons I never bothered a whole lot with the 25/06...there was just never much need.The two cartridges seemed so much alike in the field I could not really distinguish between them.
My present Roberts,a fine custom on a pre war M70 action, gives a sedate 3000 fps with the 100 gr bullets and I will leave well enough alone....I know what a 100 gr Partition is capable of at that velocity level.That said the manual loads are interesting but can be improved upon pretty easily without blowing yourself into DNA...or even coming close for that matter.
