Redbull pointed this out in his latest video. Well... got one of those too so maybe myself and Mr.Redbull can do a swap so I can see if it even hits the mark out of 5". He may have a 5.25" barrel which would give the benefit of a doubt!
http://www.doubletapammo.com/php/catalog/product_info.php?cPath=21_25&products_id=34
LOL! I wonder if they know .400" barrel length doesn't make up 150 fps? What a bunch of clowns. Who knows, maybe they've tweaked some of the loads to do a bit better anyway. Time will tell, but with Double Tap's track record I'm betting a big resounding NO. Good grief, what next, flying penguins? Sorry for the rant, just fed up with them.
If Mr. Underwood published the velocity for his 10mm ammo based on a 5" barrel and then fudged the numbers similar to what DT does we'ld practically be at rifle velocity. :o
Somehow I don't see the antics ending from Double Tap. Reason being, if they were going to, they would have ended the antics a long time ago already.
Keep the ammo the same and change the barrel length doesn't look good.