I know in Texas they are legal in other stated I dont know but the prices are 300.00 for the license with ATF and then the cost of the suppressor which normally runs 600+ for a good one. Im using a silenced 17hmr for short range varmint up to 200 yrds and all I hear is the click and a small piff.
You should be able to do a search on suppressors in "Missouri" and get an idea if its legal there.
Stacy
All states have to have a form filled out and approved by a local law enforcement official. In colorado it depends on getting your county sheriff to sign off on it. If I lived a mile south I could have one but not in my county. Find a class two dealer in your area and ask them. I called AWC(suppressor manufacturer) and asked them who they deal with in Colorado and then called thier dealer here and got the area specific info from them. I wasted about 10 calls around the ATF and got 11 different answers.