As I recall, it isn't the strength, it's the length. The heavy Garrett's are loaded long, and the nose of the bullets will stick out past the cylinder.

The slightly lighter Garrett will fit.

Check the Garrett website, look at overall length.

It is an O.A.L. question. Garret's heavy is for (fits in) Ruger DA's and Dan Wessons only. The "lighter" load will work, as will the Buffalo Bore loads.
Jason