I'm going to give this question a yes answer, with a few mandatory requirements. The Roberts is a low pressure cartridge, with top loading manual loads held to under 50,000 psi or cup, which is at the upper limit of real precision cast bullet accuracy from standard rifles. To produce really competitive target accuracy with cast at high velocity, a special throat is required with bullets bumped, or swaged to a precise fit to that throat, and with only the gas check outside the throat and in the case neck. Quite a few Cast Bullet Association records have been set with bullets of this type, many of them from LBT molds. Some of these boys are pushing their lead out at over 2600 fps, and using the highest quality barrels they can lay hands on.
Ponder how well the bullets are constrained from obturating out of balance with the above setup, and the fact that friction in a super smooth high grade barrel is as low as it is going to get for lead. -- To get close as possible to the CBA bench resters performance using a standard rifle, send me a throat slug from the gun of interest, and provide all the essential measurements and information I ask for. I'll tell you if I think your gun is a good bad or poor candidate, after I look at and measure up the slugs, then I'll make you a bullet that fills your rifles chamber and throat in a way that obturation unbalance is minimized when working at high pressures. Use LBT bullet lubricant, and, if you lap the gun, if push through slugs indicate to you that it needs it, one inch groups at 100 yards, with 2500 fps shouldn't be too difficult to obtain.
Don't even mess with a mass produced bullet design, or any other bullet lube. They are what have convinced the world that only low velocities can produce accuracy with lead.
