The .45 ACP cartridge is considered to be 'rimless' and as such, nobody makes a speedloader for them, in the conventional meaning of the term "speedloader."
You can load and shoot the ammo in your Model 25-2 without moon clips just fine, they headspace on the case mouth. They won't eject by pushing on the ejector rod, though, as being rimless there is nothing for the ejector to push against, you will need to pick them out with a fingernail or push them out from the front of the cylinder with a pencil or something.
The moon clips are usually used as speedloaders in these guns. Besides the 6 shot full moon clips, there are also the original 3 shot half moon clips and 2 shot clips available as well.
Your Model 25-2 also shoots a cartridge called the .45 Auto Rim. It is, basically, the same case as the .45 ACP with a thick rim added to it, so it will function like conventional revolver rounds. HKS makes conventional speedloaders for this cartridge. It is not carried too widely by many gun stores, so it may not be an option for most of your shooting use.
