You either failed to chamfer the mouth, which caused the bullet hang up on the mouth when seating, which pushed it down, collapsing the the shoulder.
Or your seating die is down too far and started to crimp the mouth, thus collapsing the shoulder.
Either way, I doubt it will even chamber at all. If you can pull the bullet and powder, you should be able to fix it well enough to resize and start over, maybe?
FYI, don't crimp bottle neck cartridges unless they are to be used in a tubular magazine or machine gun.
How to adjust a seating die- Put an empty cartridge in the shell holder, thread the seating die in until you feel it contact the case mouth, back it out 2 turns. Then adjust the seating stem only to the desired seating depth.
GS