welding flash hiders for barrel length calculations does not work- the CFC only counts the rifled portion of the barrel. ( i believe it may count for overall length of the firearm, but not for the barrel - which has to be over 18.5 inches for a semi centerfire to be non-restricted)
Ellwood Epps will replace the barrel with one over 18.5 inches and re-register it as non-restricted. contact them for pricing. I plan to get one done when I get the scratch together

- which has to wait unfortunately until I sell a few guns