I think there's a dimensional issue at hand. If a factory round chambers easily and your handloads don't, there's a dimensional difference. Only 1 or 2 thousandths in the right place will cause this problem. So you need something to measure your reloads to at least 1/1000ths inch.
One thing's a good micrometer or caliper graduated in thousandths.
The other's a case headspace gauge to measure the distance from the case head to the case shoulder's reference point. RCBS Precision Mic or Hornady's case headspace tool are good choices.
Do you have these and if not, are you willing to buy them? Otherwise, it's gonna be very difficult to get the problem resolved by on-line chit-chat in reloading forums based on your visual observations.