smokey92
Speer Deep Curls do not come with sabots, you are buying a box of bullets meant for reloading, then you match them to the sabot that you or your gun prefers, in most of my ML's I am using a MMP HPH-24. I have also shot them with Harvester 'short black's or regular Harvesters but here in the cold I prefer the MMP.
http://www.gamaliel.com/cart/home.php?cat=1727
Nosler Patitions, both the .451/260 and .451/300 have been discontinued by Nosler. Nosler .458/300 grain bullets are still available. You still might be able to get some Noslers from Widners Reloading.
The Nosler is the more expensive - top of the line bullet while the Speer is much less expensive production bullet that works great.
If you were going to look at a premium bullet that is available I would suggest you look at the Lehigh .452/250 grain DOA.
All of the mentioned bullets are normal sold without sabots, although you might be able to find some Nosler bubble packs that come with a sabot - it will be a MMP HPH-24.