Saiga-12. Converted to proper configuration by none other than TROMIX!
Why?
12ga is the most common shotgun gauge available.
Powerful enough to stop a big block V8 with slugs. (We trained on how to do that in the Army using 12ga pumps, so YES, 12ga slugs WILL kill an engine!)
Also, if a REAL Tigr is being imported and it's not ridiculously priced, I WANT ONE! I looked at the current crop of SVDs (yes, I know they're not the same (SIGH) ) and they look like they were made using a dull saw.