That's a pretty large spread. 10 feet diameter spread at 50 feet range - What do you need that for?
I don't expect that you'll get that naturally. I suspect you'll probably get about half that spread naturally depending on your exact loading method, loading quantity, bore size and velocity.
It is possible to widen shot patterns with what are known as shot spreaders - one variant of which looks like this:

Basically, this X piece helps push apart the shot spread as it leaves the muzzle, and widens the grouping by some degree.
The solution to your loading problems is some kind of wad behind it - although some of these have been suggested already... newspaper, a plastic bag (behind the ammo, not with the ammo in it), milk jug caps, old rags...
Anything like that will work - and you'll probably want something in the front of your load to hold it in place and stop it falling out. Cotton wool works well.
As a side note, try and keep your wads reasonably lightweight but also air tight for best velocity.
Gaderelguitarist wrote:Though you'll know soon enough if Ragnarok comes knocking (I don't mean the battle between Valhalla and Jotunheim)
Hmm, mythological humour.
