Is there a suppressor that you can use on .223 and 9mm? Also I want to get a suppressor for my Walther P99 and I know I need a new barrel. Who would have one for me?
You cannot use the same suppressor for 9mm and .223.
As for the P99 barrel, you have three choices:
1. Jarvis barrel
2. Factory german Walther barrel from Earls
3. Send your barrel to Adco and have it extended and threaded
If Jarvis actually has the barrel, it's the least expensive way to go for a barrel replacement. If they don't, you will grow old waiting for one.
The Earls barrel is a real factory German Walther barrel. It drops right in and works perfectly, but it's the left hand thread and it's quite a bit more money. When I wanted a barrel, Jarvis didn't have any in stock, so I got the Earls. There is kind of a cool factor having an "official" barrel, but if Jarvis had them, I would have gone that route. Some of the Jarvis barrels can be tight so there could be some "gunsmithing" to get them to fit and the break in could be a little longer.
Third option would be to do what I just did with my P30--send the barrel to Adco and have it extended and threaded. The P99 barrel is 4" long, so it shouldn't be a problem. This is the least expensive option, although your factory barrel is now threaded and that could affect re-sale.