http://shockwavetechnologies.com/site/?p=3524
Shock wave made a call
Wow, too bad that isn't on official letterhead as that would be money! Is length of pull the distance between the trigger and the butt end of the stock?
He then gave me a bit of further guidance for our customers:
- By “permanent affixing,” ATF considers that to be adding permanent Loctite to the large set screw that secures the Blade into the dimples in the KAK tube. As long as you don’t red Loctite the set screw in place, ATF considers it to be “temporarily placed” and “perfectly okay to shoulder.” (He didn’t beat around the bush on this topic.)
- “Length of pull”—for lack of a better word regarding pistol braces—begins to enter a “gray area” above 13.5″. Above 13.5″ begins “to enter shoulder stock area.” (His words. I believe this has to do with the “comfortableness” aspect.) On an AR-15, the “length of pull” for the Blade is approximately 13.13″, so no issues there. But if you use the Blade on a firearm that requires a large adapter of some sort, please make sure that you only use the dimples up to the point that you remain below the 13.5″ length. Stay below 13.5″ and according to ATF, it’s okay to shoulder a Shockwave Blade.