Had the same problem with the same mould. Got a Lee factory crimp die that fixed the trouble. It has a sizing ring that resizes loaded rounds to minimum chamber dimensions.
If you haven't slugged the barrel, I would suggest .451 is a poor choice for a cast bullet. .451 might work for a jacketed bullet, but normally a cast should be at least .452. Not sure why you are sizing a Tumble Lube design, but your choice; I would not bother.
Again, check the diameter of your cast bullets, and also determine if the seated bullet makes the cartridge too large to properly chamber, or if the seating depth is too long preventing easy seating.
https://imgur.com/hbpRr25
This is what mine look like.
I use multiple bullet designs, all get sized to .452". Never trim cases, and always taper crimp. None of my 1911s give me any pain. I would try some factory ammo to see if the gun works with other ammunition and decide if the issue is the gun or the ammo... Get a chamber gauge to verify your reloads are good to your chamber.
If you haven't slugged the barrel, I would suggest .451 is a poor choice for a cast bullet. .451 might work for a jacketed bullet, but normally a cast should be at least .452. Not sure why you are sizing a Tumble Lube design, but your choice; I would not bother.
Again, check the diameter of your cast bullets, and also determine if the seated bullet makes the cartridge too large to properly chamber, or if the seating depth is too long preventing easy seating.
https://imgur.com/hbpRr25
This is what mine look like.




























