Donneyfl suppressors as far as I can tell have no identifiable caliber notation so how do you know for sure you received the correct suppressor as far as caliber is concerned?
The way they are designed, the tube is what is engraved however the core is what denotes the caliber. Easiest way to tell is probably to measure the exit hole ID...... unless they are marked somewhere I don't know about.
There are several ways you can get a quick easy check. Let's assume you don't have a Micrometer or caliper to measure the exit hole on the suppressor. You could get a (as an example) 1/4 " drill bit and use the mounting end to check the bore size. Just try alternate bits till you see what you have. You could also go to the hardware store (home depot) and get several sizes of wooden dowels to check the size. Stick your LDC in your pocket and test it on the spot in the store.
Your measurement should always be larger than the caliber selected. So a .22 LDC will measure greater than .22. Email DonnyFL and he will tell you what the spec should be.
By the way your question about not having a size id on the LDC is very valid.
I have a Sumo that came on a .22. Mouse fart quiet. The exit hole measured 26.7 so I tried it on my .25 and it works, sorta. When Mounted on the .25 it is quiet but not quite Donnie FL quiet. I'm assuming the difference between the .22 and .25 models is the enternal baffles.
Thanks for your ideas. I bought supposedly a 25 cal. Donny said this should measure 8mm at the exit hole. Donnie also said sometimes the dealers and he would recommend a size up like a 30 caliber to reduce the chances of clipping and the 30 caliber works really well with 25 caliber and gives you the option to move up to a 30 caliber later.