With a bare barrel in one hand and a 115/124 FMJ in your other hand, starting at a 45 degree angle, “drive” it up the feed ramp and around the corner into the chamber.
It will generally feel smooth without much resistance throughout the path.
Then, try the same thing with 147 flat nose.
You’ll likely find a large resistance or a sticking point as the cartridge makes the final turn into the chamber.
This is the condition that can be improved by rounding the junction of the feed cone and chamber.
Only do the minimum amount to get good feeding. Excess material removal results in an unsupported chamber and the potential for bad things to happen.