I was still in rookie school when speedloaders were first authorized for my organization, At the time we carried S&W Model 10's with 4" heavy barrels. Speedloaders were NOT issued but those of us then "buffs" hit the local blue vendor forthwith. Only ones then available (to the best of my knowledge) were those made by the Dade Screw Company. (Might not be exact name of company.) They were cylinders that were surrounded by a spring. Rounds were held at the primer end and pushed past the spring to load. Functional? Yes. Perfect? No. But better than drop pouches, for certain.

BTW, at the time we still carried 158 ball ammo. Hollow point ammo did follow soon thereafter. Do not recall what that was exactly.

Be safe.