If the barrel is 16" in total length "with a permanently attached" (pinned and/or welded) you should be good to go. I would suggest you verify this yourself and not just take my word on it.

I'm assuming that you are buying an AR (10 or 15) type rifle with a 14.5" barrel, and that it has an IZZY or other type of flash hider permanently attached to the barrel. Most likely the rifle would have a disclaimer of "All NFA rules apply" if the barrel length is less than 16" and the flash hider was easily removable.

You would also need to meet the minimum .24 caliber requirement for Washington. 6.8 SPC or 6.5 Grendel are two pretty good all around calibers for deer. We have taken a bunch of deer with the 6.8 SPC. 2800 FPS with a 95 grain bullet, 2400 FPS with a 130gr bullet. Very accurate.

Rifles with barrel lengths under 16 inches are considered NFA items and are called "short barreled rifles" (SBR's). SBR's are regulated by the BATFE, and you would need to complete a form 3 (to buy a completed SBR) or a form 1 (to build one yourself), then send in your application, passport photos, CLEO sign off, or trust documentation, along with a $200 check to the BATFE where you get to wait for 60-120 days while they go through your background and finally approve you. After approval, and only after approval, can you then assemble or take possession of the SBR.

One tricky issue here in Washington. SBR's aren't legal to own, possess, or use. That is an issue we'll take up next year.

Again, don't take my word as the gospel. Research it yourself, because screwing up and getting arrested for an NFA violation means Federal charges, and Federal prison.

What are you getting?