Advice on barrel shortening and crown

Sunday afternoon first time DIY recrown so need advice.

Wondering if I can use a cut-off wheel on my 4" grinder rather than use a hacksaw to shorten a barrel?
I can make the barrel cut straighter with a cut-off wheel (I usually end up with more of an angle using a hacksaw = more filing).

But will the cut-off wheel get the barrel end too hot so affecting the metal and/or will it leave too much nasty crap in the bore?

Also which Dremel bit (if any), should I use out of these three for making the crown?

Attachment 190669

The cut-off saw is OK then the barrel needs to be carefully filed square from all sides. Do not use grinding stones for the crown! It should be cut with a proper tool or lapped with a ball on a rod to turn it (gently backward and forward like lapping a valve seat).

Lapping compound or something like Chemico - brass door hinge pin in a drill. I've used that at a pinch to tidy up a rough crown on a .22
What I did note is that you cannot just put the pin head into the crown area and spin away, you needed to work the drill in a angled fashion to get it to polish properly. I'm guessing thats similar to the motion gundoc is describing.
Rough as guts, but it actually ended up with a pretty decent finish, so much so that I've used it a couple of times.

Also use foam ear plugs - push down the barrel to just before the area that you're doing the work. Just don't forget to remove :)