Everything else being equal (pressures, magazine and barrel length, etc.) the .284 is capable of about 4% faster velocities. This means the same bullet in the 7mm-08 getting 3000 fps will get around 3120 in the .284.
Comparing claims by different handloaders about potential velocities doesn't mean much. Handloaders who get magic velocities with a .284 are also likely to get magic velocities with a 7mm-08.
I had no intentions of hot rodding this cartridge. But I was a little deceived maybe with R17 as I kept working up looking for the traditional pressure signs -- flattened primers with cratering, ejector marks, stiff bolt lifts, etc., until I got to 3200 fps with the long 140-gr TTSX. I thought then this is just too fast so I worked down to 3050-3075 fps with great accuracy. I've read that some of the traditional signs occur long after high pressure is reached but it seems intuitive to me that even with R17 (or any powder) high pressures should result in a stiff bolt lift which I never experienced with these loads.
