OP,
Here is another option for your Czech rifle to allow you to add a US Muzzle device at will....
http://www.cncwarrior.com/ProductDetails.asp?ProductCode=25797
It is a US made, threaded barrel extension, thus solving the length problem, and allowing muzzle devices to be added.
Now to have this installed you can send it out to InRange, or a competent gunsmith; There are also numerous threads on this very board on how to do it yourself. Please note, if you choose to do it yourself, you must understand that as soon as you remove the barrel extension, you have created a Short-barreled rifle, and if you leave it that way all NFA rules apply. In the past the ATFE has been lenient on individuals removing the barrel extension and expediently replacing it with another device to bring it to the legal limit... this is something to keep in mind if you choose to do it yourself... In other words, if you do it yourself, it is a couple hour project maximum, not a "I'll remove the extension now, and once my new extension comes in I'll put that on" DO NOT remove the existing extension until you have the new extension in hand, as well as every tool you could need to replace it! Remember you may have to chase the threads on the barrel to get the new extension on, so you better have the die, die holder, and cutting fluid on hand before you begin.
This is where this guy helps you . .
"Intent" plays a large role in the government bringing charges against you. If you just happen to have your muzzle extension off & your new replacement extension laying on the workbench next to the MAPP gas torch and high temperature silver solder when Johnny Revenuer walks in, it's obvious that you intended to abide by the law. IOW, you are in "constructive possession" of a legal firearm.
This is why it's very important that you have all your parts before you put your rifle into a temporarily illegal state.
Yep, that's why I stressed to make sure you have EVERYTHING you may need in hand before you remove your existing extension... just because you have a legal extension back at home and you are out shooting your now NFA firearm because you removed the original extension, and decided it would be "cool" to take it to the range without the extension, doesn't mean that Johnny Law ATFE agent will give you a pass, because you "intend" to make it legal... hence the "couple hour project maximum" point I made... better to be safe then end up with a Fed. firearm beef!
