454 Casull Help

[Reloader78]

So I'm trying to reload some 454 for the first time. I have the RCBS carbide set of dies and some new Starline brass. I'm having a serious problem getting the bullets to seat in the case. They start easy enough, but then they get really tight. You can see from the picture what happens if I force the issue.
I have a few rounds of Magtech ammo in the fired and unfired state. If I measure the unfired bullet diameter, it is the same as the ones I'm using. If I size the once fired brass and try to seat a bullet, it does the same thing as the Starline brass.
I'm very confused as to why these are behaving this way. Anyone have any ideas?
In the picture, the one on the left is just the bullet sitting in the case before trying to seat it.
The bullets measure 0.4515".
Thanks

 

[michacooks]

Are you flaring the case mouth prior to seating

 

[Ga G Man]

Are you using the correct powder? Are you compressing the load?

 

[Reloader78]

Are you flaring the case mouth prior to seating

Yes, I've even tried flaring it way too much but it will still only go in that far.

 

[Reloader78]

Are you using the correct powder? Are you compressing the load?

I'm using about 29 grains of H110, but it will do it even without powder in the case.

I'm almost thinking the resizing die is off somehow.

 

[Reloader78]

I figured it out. The root cause is that I'm stupid.
I didn't realize the rcbs seating die was putting a crimp on as well as seating the bullet. I backed the die out and all is well.