bullet bulges out the casing when seated

[gewehr76]

Either factory crimping die for that caliber or bullet sizing die should solve the problem. 460 to 452 is no problem to size them down, just use some lube.

 

[Archer Sam]

.451 or .452 only in a 450 Bushmaster. I use Barnes bullets(716876450275) in my 450 They are .275 gn TSX FB These make a nice ragged hole in a target at 100 yds
They have a new Tipped TSX BT I want to try(716876 45026 8) 250 gn.

 

[Janeau]

My guess the op did not run the expander at all or nor deeper enough to flare the case.
This forced the bullet to go sideway..cause of too much seating pressure.
Seen this before.
This is not a die problem, but a user problem.

 

[KotKotofeich]

My guess the op did not run the expander at all or nor deeper enough to flare the case.
This forced the bullet to go sideway..cause of too much seating pressure.
Seen this before.
This is not a die problem, but a user problem.

That was the answer I thought I saw a thread on and was trying to recall... so it's valid advice for this kind of behaviour... but my case was much dumber - mislabeled (not by manufacturer) bullets