How to make your own frangible rounds

In article , C J Campbell wrote:

Pilots who like frangible rounds but can't get any of the government issue
can easily make their own by loading .45 cal shot shells with bits of wire
and small birdshot. These can be fired from a revolver, but not an automatic
pistol. At close range the round will act just like a slug, but it will not
penetrate wallboard, extremely thick clothing, airplane windows or aircraft
aluminum.

When I tried shot loads from a revolver, the seemed to spread at
around a 30 degree angle. The only place it would "act like a slug"
would be within an inch or two of the barrel. I always assumed that
was because of the rifling. These were .38 instead of .45, but I
can't imagine they act *that* much different. Do they?

Mike Beede