I have found that the magazines for the .45 Shield allow very little clearance front to back(not as much as say the mags for the 9MM Shield) for the .45ACP rounds. It is very easy to create a binding situation if the .45 round is not seated fully toward the rear of the magazine. When using my Maglula loader, I have found it best to hold each round against the rear of the magazing with my thumb or finger (depending on how you hold the Maglula in your opposite hand). When releasing the tongue of the loader, if you do not hold that round to the rear, the tongue can slightly move the round toward the front side of the mag. Result is that the tip of the bullet will either not clear the front of the mag when the loader is pressed down, or if the round does press down, the tip of the bullet will be touching the front of the mag. This can result in the rounds in the mag binding and tipping a bit which will stop or hinder the progression of rounds into the magazine.
If this happens, simply take the mag and smack the rear of the mag against the heel of your other hand so that all rounds seat fully to the rear of the mag and then proceed. It is also recommended that when you finish loading a mag, either by hand or with the loader, smack that magazine against your hand to move all rounds to the rear of the mag. This will reduce the incidence of malfunctions. The reason (I think) that the tolerances inside the .45 Shield mag front to back is so tight is that S&W wished to keep the grip frame the same size as the 9MM/40 Shield frames, which resulted in less clearance for the rounds in the mag. Keep the rounds completely to the rear of the mag and you will have no problems with loading or feeding, in my experience.
These mags, as well as the recoil spring assemblies in the Shields, are very stiff to begin with. I make it my practice to lock the slide back on the gun and to fully load the new mags with my loader before heading to the range. I leave the gun and mags in this condition for a couple or three days before going to shoot. This allows those springs to begin to take their initial "set" and things work better all around during your first firing and loading session. Things continue to get better as you shoot the gun. Two to five hundred rounds fired through any new gun will result in smoother and better function! I have experienced no shooting malfunctions with my .45 Shield since new and I'm up to around a thousand rounds fired through it at this point. I can load the mags by hand, but for my old arthritic hands, my Maglula loader is the best money I've ever spent.
