We get a lot of questions about what Arbor should I use.
Most (perhaps all) of the moon clip loading tools on the market that use interchangeable arbors use the same hardware. Specifically a 1/4 x 20 bolt to mount the Arbor. Good News.
Arbors need to be sized so that they fit the center opening in the moon clip with about 0.005" to 0.008" clearance. Any larger and the moon clip would tip up as the round is pressed into it. Size Matters.
Manufacturers of moon clip loading tools make arbors to fit a specific moon clip. Take the 45 ACP moon clip for the S&W 25/625. That revolver and moon clips comes from a military design and all moon clips available have the same center opening. So our arbor for the 45 ACP will fit any 45 ACP moon clip made for the S&W 26/625 revolver. Good News.
Let's look at the S&W 929. An 8 shot revolver chambered in 9MM. Our arbor ARB-9MMx8-1 is specifically designed to fit our moon clips. The moon clips shipped with the gun are not from Revolver Supply and have a different sized center opening. We put together an assortment of 3 arbors ARB-9MMx8-ASMT-1 This assortment will fit our moon clips and the moon clips shipped the revolver. Perhaps Good News.
The diameter of the arbors are listed on our web site in the arbor section. Look around.
A common phone call goes something like this. You bought a Taurus xxx and have moon clips but need an arbor. You will need to measure the center opening in those moon clips and then see if we or someone else sells an arbor that is close enough. Or beg someone to make a custom arbor for you. We can do it but give us a couple of weeks to get to it.