I'm considering a hardcast bullet like the ones from from Rim Rock.  I read that these are used by Buffalo Bore.  The 200gr and 220gr Rim Rock bullets have no crimp groove.  Would a light crimp using the Factory Crimp die suffice, or is any crimp at all inadvisable?

Good question.  Especially with a lead bullet the neck of the case needs to be belled some to allow for the bullet to ease into the case when seated.  No matter what it's a good idea to crimp enough to eliminate the belling of the case.  I use the Factory Crimp and only lightly crimp the case to the bullet.  I shoot Glock's in 10mm and most of the headspacing is actually on the extractor so too much crimp.... well... I do not know how much too much is.  Good reloading practices suggest just eliminating the bell and maybe a bit more.  Other guys on this forum shoot other brands of 10mm guns and the tolerances may be different.

Forgot to mention.  I have had fantastic success with the Montana Bullets 200gr WFN PB bullet cast to .401 . 

The important part of seating cast or coated or any bullet without a cannelure is to seat bullet to proper depth without any crimp being applied as the bullet is being seated.  Why?  Because the crimped casing can grab the bullet as i is moving and before it is fully seated at depth.
The two separate steps of seating and crimping make for more quality and reliability over all!  Crimping the bullet without any movement allows the casing to be pressed directly against the bullet while it is not in motion to snag...

I agree 10,000% with Shadow. The 10mm has the ability to be fickle on feeding. I have found that the separation of crimp and seat is essential to the function of the ammunition.

I still seat and crimp in the same step on other calibers. In 10mm i seat and debell but follow up with the FCD as I am only removing the bell during the seating. I went from hiccups to happiness with that change.

The Shadow gives great advice.  I learned long ago to seat and crimp separately when using cast bullets.

Here is the second thing to keep in mind.  Bullet size.

A strong taper crimp and a cast bullet can actually swage the bullet diameter down a thousandth or two.  This means that you carefully sized and lubed bullet is under spec when it actually heads down the tube.  And if it is a hard cast it won't obturate back up and seal the bore.  Which means gas will blow by, forming superheated plasma jets that will melt bits of the lead and cause severe leading.

I don't use a FCD with lead bullets for this reason.  The carbide sizing ring at the base is often tight enough to swage the bullet down even if you don't engage the crimping action.

For 10mm, a standard taper crimp die adjusted to remove the bell is plenty.  Ammo should be .423" at the mouth.  No roll is needed for in-spec velocity and pressure, even with heavy for caliber bullets in my experience.

sqlbullet  great reminder about the FCD squeezing the bullets smaller.  Learned that when I first tried to use the FCD as a finish crimp...bullets could be spun (loose inside) as seated inside the casing.  That leads to poor ignition quality and in most instances leading of the bore.

The 1/8" Die Spacer rings I use do raise the the seater/taper crimp die high enough, that the start of the tapered section is well above the case mouth.  This helps to also keep the bullet from getting shaved by the case mouth.  That could leave alloy rolled up on the edge of the casing, that changes headspacing, if enough got outside and folded down the casing sides, they'd never pass the case gauge.

But using that FCD for the carbide ring as a pass through sizer was a no brainier.