If they are the headless bolts that many of the cue makers use, they are 3/8th x 16. If they look like a large screw, they are the same thread pitch but the end is tapped for an allen bolt to hold the bumper on.
So, if you are able to find the large screw type, you will have to drill and tap your own.
If they are the larger headless bolt like Joss uses, it is 1/2 x 13.
Generally, these 2 thread pitches are considered to be industry standard as far as cue weight bolts are concerned.
All should be available at your local bolt supply house. That is where I get mine.
Other than having to tap your own screw type, you're good to go. I can't say for sure what type Action uses but if they are the industry standard, they will probably be one of these thread pitches.
If they are a b astard size made in China, you will have to take the bolt out and see if you can match it up. If it is in fact a made in China bolt, you're probably out of luck matching it with anything North American. For example, the Chinese Radial pin is not anywhere close to our Uni Loc Radial pin. Shafts will not interchange. Altho they do look very much like our Uni Loc.
If you need a tap and drill bit for the screw type and you want to try your own, both the tap and bit are El Cheapo so won't break the bank on ya. The allen head screw that you would drill and tap for is 8/32. If I am not mistaken which is not uncommon for myself, you will need a 3/16th drill bit. Darn, and I know I have the tap but they are in the tool box in the shop.
The headless bolts are usually pennies each so you can save a bit of money and your time waiting for them to arrive if you go shopping.
If you figure out what you need, I can weight some of mine and give you an idea of bolt length weight ratio. That way, you will have an idea of what length to buy.
If you go that route, you will need a long handle allen wrench but they are also cheap and you will end up using that many times anyway in the long run.
Hopefully you will be lucky.