Some single stack 9mm magazines and other similiar mags can be difficult to load the last few rounds as can some double stack mags.  There are some expensive loading tools, but with the rate at which I lose such things not really cost effective.

On one level, the Glock loader will load almost anything in the same cartridge length without too much fuss.  They are everywhere.  Considering how many I have lost and then found another one, seemingly every where.  The negative to the Glock loader is that its cartridge push finger is flat and slips off the top round being depressed to allow the next one to be inserted.  But they do work.

If you don't already have a Glock loader to use, there are inexpensive metal options.

-there are several models of 9mm sub-machine gun loaders made from metal that work. 9mm ones, NOT some really long thing like the Finnish "SA" marked loaders for the 7.62x25mm conversion mags for an originally 9mm Finnish buzz gun.

-ProMag makes a general purpose loader for double stack mags.  It works for them as intended.  On a single stack magazine, you would think it a loose no good fit.  But if you close the front of the U shaped body that goes around the magazine, it fits snugly on the front of things like the S&W Shield mags or other single stacks. The upside down U that is the cartridge pusher finger is a little forward of ideal. If you close the U slightly to the rear, it pushes the top round down and allows the new cartridge to be inserted easily.

-Ruger has a metal double stack mag loader that with the same mods works, but it doesn't have the little shelf on the rear to help pull it down that the ProMag model does.  The ProMag works better.

Even though these are double stack mag loaders, the slightly closed front tracks the Shield mag body or other single stacks in the front. The slight dish in the cartridge pusher finger, the bottom of the U, locates the rear of the loader just fine.  With the arced pusher, either works better than a Glock loader.

I mention these because you see them floating around loose at shops and shows and no one knows what they are good for. Browning and Beretta have the same things for their double stack mags. A minor tweak in two spots and any of them make a Shield or other single stack easy to load. Plus they go for $2-3-4-5 if you spot them or a little more if you have to actually order one.

See the photos at the URLs.

http://www.brownells.com/shooting-accessories/speedloaders-accessories/magazine-speedloaders/magazine-loader-sku780000928-11837-28514.aspx

http://www.handgungrips.com/Magazine_Loading_Tools/1968/c/2940

I know these styles for 9mm length ammo work because I have used several variants.

What might even be better is the Ruger .45 auto single stack mag loader. It would be slightly longer.  II don't know how wide the cartridge push down finger is. It might be too wide for a 9mm width feed lip gap.  It might still fit a single stack 40.   Maybe someone has one and can try it for width in a 9mm mag or a .40 mag??

http://www.brownells.com/shooting-accessories/speedloaders-accessories/magazine-speedloaders/magazine-loader-prod11869.aspx

Whats wrong with a uplula? It works all my handgun mags....

Plus if you have/get another gun, you can use it.  Worth every penny if you shoot alot.

Nothing wrong at all.  Just $.

Saturday at a show, I bought two metal ones for $2 each.

I don't shoot alot and I've long gotten my moneys worth out of it, everyone who's used it loves it. $20 gonna kill you?

OK, fine. But I do shoot a lot.  Put one each in a couple different gear bags, in an extra car or two, and end up with kids permanently borrowing stuff.  Pretty soon at the current $35 a piece, you might notice.

Gotta love internetters.  Supposedly a source of info, but really just a jump off point for contrarians.

(Kindly note no one said the expensive ones weren't useful.  The point was an inexpensive alternative.)

I only use USGI strippers & spoons to load AR ammo.
Never got into the handgun mag loaders. I found it's faster to load by hand.