Federal brass which is run through my FL die just like any other makes with no issues at all will not hold a bullet firmly.
The only thing which keeps the bullet from falling deeper by it's own weight is the crimp and with a crimp most bullets will spin by finger pressure even with a very hard crimp.
Federal tells me their brass is no softer nor thinner than anyone else brass and was trying to lay blame on my FL die.
I am not capping on Federal just wanting to know if I alone had this problem or what.
I had this issue about 5 years ago and came into some FC factory ammo which is now once fired in both of my .41 mags and once fired...

it sounds like a die problem, I've seen it with brass that was new and not resized (which is how I realized I hadn't sized it yet) The only thing that does not make sense is your other brass, unless your chamber is tight enough that it's not allowing the brass to expand to the point where the federal brass is which would mean all your doing is depriming and not actually resizing.

With every straightwall cartridge I load, the case mouth must be expanded after FL sizing just so one can start the bullet into the case and seat it.

I have loaded 41 mag. for a friend of mine at work and I have never had an issue with it. I use a snug crimp on it but I don't go crazy with it. I use Lee carbide dies if this is worth anything.

Thanks Guy's.
I think Wapiti rod is right about being a die problem.
There is something about FC brass that my die just will not size properly.
I maybe ordering new dies soon.
BTW, I own two different .41's. A total titanium 6.5" Taurus Tracker and a S&W 657 pro center.
Of the two the Taurus has a tighter chamber, it does not matter which gun the federal factory ammo is shot out of the results are the same.
New dies may take care of this.
Elk season is not far off so I need to get going.
Thanks again Guy's.

I found part of my answer.
The Federal brass as I expected is thinner than R-P or Win brass.
I took a Federal factory loaded round and measured below the crimp and found it measured .427" and a hand loaded round measured at the same place goes .430".
The R-P and Win cases load well and grip the bullet tightly before it is crimped unlike the Federal.
Federal I will use for target practise with cast bullets and use my other head stamps for WAR SHOTS.