I've had the same problem with a compression die folding the neck over on a cartridge after I had loaded the powder. I've used the expander die but it does deform the wad a lot. Grind or file a slight taper on the expander plug. You can hold the plug in a drill press or even a hand drill to do this. I'm sure you can get it to work at much larger than .30"

Chris, that's a clever idea for sure as you can see what is going on instead of trying to feel the plug entering the case.  I think I solved my problem by reverting back to my old Lyman tong tools.  I have been using one to deprime now that I am not sizing the brass very often and have one set up to deprime 30 caliber and above and another die for 22 caliber to 30.  They work slick.  I dug in the old box of 310 dies and found a seating die for a 45-70 that I will never use again and it measured 0.39 so I filed the recess for the bullet nose off and gave it a try.  Twenty times easier than the BACO die and seemed to work without damaging a thing.  So now I am using my grandfather's Ideal tools made god knows when and my Herter's turret press that my dad bought in 1960 when we retired the Ideal for 30-06 and I just used it for my 7x57.  Tom

Yes you can use an expander die to compress the powder. Just be sure that the diameter of the expander doesn't open the case mouth to far.
The BACO expanders work well , but you do have to be sure that the case is fully pushed into the shell holder and the wad is below the case mouth. It also helps a lot if you bevel the front edge of that expander just a bit so that it's not quite as sharp.

I make compression plugs that fit regular M die bodies.  Easy way is start with the correct size bolt then turn down the end to suit the cartridge case, A little bit of taper On the end helps inserting the die.  Does not take much.  

Lots of M bodies available here is a link. Get one that suits your cartridge O/A length and Diameter. Too big allows easy misalignment 

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Often thought about buying a large internal diamater  M body & sleveing with a leade to index the case before the compression plug enters.  Never tried it .    Agree some of the loading tools you buy on line must be made by people that don't load cartridges 

Boats

Most presses the shell holder ram fits are sloppy. Thats why taper is needed were the case enters the die. Compression plug no taper is recipe for trouble.   

Boats

Craig agree with you. Locked down tight can cause trouble. Really die should establish concentric. All the press ram and shellholder do is press. Floating not inducing something else in the process best. 

If you look at the small arbor presses bench shooters use They don’t have fixed shell holders or screwed in dies. Everything floats.

Boats

I use an expander die to compress powder charges.