For what it's worth, I've done exactly this. When the 123 gr FMJ bullet and powder were transferred from the 7.62X39 to the 30-30, the MV dropped by about 250 fps to about 2100 fps. I first checked for adequate neck clearance for the 0.002" larger bullet and I had plenty.
I didn't load the bullets backwards, but I went "full hillbilly" and made a simple jig (7/32" hole drilled into a piece of 1/4" steel and tapered for a decent fit with the bullet tip taper) and using my belt sander, ground down the tip of the bullet to a flat slightly larger than the primer, i.e. about 7/32" or 0.218". This is not benchrest precision in handloading (it's a 30-30 Lever Gun!), but they shot as well as the 150's and 170's I usually use.
I used a cruder method. A side cutter to clip off the tip[ and then a file to clean it up.



















































