Well, I'm going to thow my ton of disagreement toward's David's post (as respectfully as possible).
I shoot my 629 weekly in IDPA practice and in one or two matches a month. Let's say that's 500-600 rounds a month. I had a small collection of Safariland Comp I's and, UNLIKE the wonderful COMP III's and decent COMP II's all the .38/.357 guys use, the COMP I's are the suckiest thing that ever sucketh.
I've talked to a lot of shooters who have tried them and every one that I've personally discussed the matter with gave up on them quickly. The COMP III's are the fastest thing going (that you can find commonly, anyway) but they are significantly different in design from the COMP I's and the "I" version is just a POOR substitute.
And, of course, Safariland won't make COMP II's or III's for .44s -- not enough of a market, they say.
Some quotes:
I did try the Saffariland loaders in .44 magnum for my nightstand gun, when I used them at the range to test them, 2 of them out of the 4 I orderered would not release the rounds easily, One wouldn't release the rounds at all. I would never rely on a Safariland speedloader for self defense.
Your experiences mirror mine. Safariland only makes COMP1 style loaders for .44s. And the COMP1s might as well be made of pure dog poo, instead of wasting a few oz. of nice plastic on them.
Comp IIIs are really slick. Comp 2s have a pretty good following.
Comp 1s are an abomination.
And my first comments on them from a post quite a while back:
Avoid the "Comp I" model like the plague. I've owned a number of them for my 629 because that's the only version Safariland makes for .44s for some ignorant reason.
They are hard to load.
They are hard to release. As in: you feel pretty dumb straining and pounding on the back of your loader and cylinder repeatedly while trying to get the catch to release. As you dance around grunting and cursing the thought dawns on you that you could have reloaded faster with six loose rounds. ...
[pound, grunt] ...
Six loose rounds in a pants pocket. ...
[strain, swear] ...
Someone ELSE's pants pocket! ...
[veins popping out, sweat starting to run] ...
Someone else -- in another STATE! ...
[ammo flung into tree line]
Imagine how utterly FLABBERGASTED you then feel when they automatically dump one to two rounds out -- completely spontaneously -- in your pocket! Oh, and when they've dropped a round or two into your vest pocket they're even closer to IMPOSSIBLE to get to release the other rounds.
Actually, only one of mine was all that bad from the start. But they all get worse with use. And that's like a few months of use, not decades. I have one left that I was using just for holding my "make ready" rounds, but as of last week's practice it is in the trash.
I guess you could say THEY SUCK.
Anyway, all that to say, the HKS model 29 twist-knob loader is the best you're going to find, short of going to moon clips. They're simple. They work. They work the same way and with the same ease every time. If you practice with them, you'll get fast enough.
Moon clips will be faster, but they require getting the cylinder cut for the clips. That is certainly worth it, but you might not care to have a permanant modification done to the gun. I'm planning on it in the near future, but haven't done it yet so I can't give any reload times to compare between moon clips and HKS style loaders.
Of course YMMV! The various loaders aren't that expensive. You could buy a few and see what you like before you send your cylinder off to get cut.
-Sam