So I was checking out the local gun shops' used guns and I saw an old FNP tactical for a screaming deal.  The only catch was it had no night sights and no threaded barrel.  

It still says tactical, still has the red dot mount, 15rd magazines and the case and literature all say tactical on them.  I figured that I could pick up a threaded barrel if I ever got a can and the deal was too good to pass up.  But now its years later, I have a can, and it looks like no one makes a threaded fnx 45 barrel or fnp 45 barrel.  Does anyone know of any options to get one?  The only things I find online are sold out, and getting on the waiting list doesn't appear to do anything.   I've been on a few for months now.

Have you tried calling FN and ordering one?
Years ago I ordered a FNP46T barrel  and several springs directly from FN.

It sounds like the previous owner swapped out the barrel and sights for some reason. IIRC the sights should be the same Trijicons the FNX uses. FNP barrels have a different locking interface shape than FNX's do, but I don't think the slides are any different so an FNX barrel may fit.

FN still lists FNX 45T barrels as a current production item, and they are surprisingly inexpensive, but they do seem to be OOS everywhere

Thanks for the help guys I'll call FN customer service and see what I get.  I'm thinking that I saw somewhere that a guy swapped the barrel from a fnx into a fnp and it worked.  Maybe the tube of yutes?

EFK Fire Dragon may be able to help.  Worth a call at least.

Thanks grandmaster, I put in a request to be notified for when EFK would do another production run and Brownells' ears must have been burning because the backorder I had from November of last year just came in!  They asked if I still wanted it and I told 'em heck yes!  It is a FNX barrel so I'll let you guys know if it doesn't work but when I did the research last year I remember finding some sources saying it would fit.   I think they support the chamber better on the FNX so that's an added bonus.  Its probably going to be a few weeks before this gets to my door but I'll let you guys know how it all works out.  Fingers and toes crossed on this one...

Interested to find out how it goes OP. Thanks for the update

I got updates...

The new barrel is in and it does not fit, however it is really close.   The box said it would need to be fit by a gunsmith, so maybe this is by design?  Heres the differences.  

The length of the barrel hood that locks into the slide looks to be about .020" long.  I think that a machinist or a careful dremel operator could knock off the amount needed to get this to work, but given the scarcityof these barrels I'm leaning towards gunsmith.  

The barrel seems to be about .010" thinner than the existing one in the gun.  The way the barrel locks up is by the recoil spring forcing the barrel up into the top of the barrel hole in the slide.  It isn't "fit" like a 1911 with a barrel bushing.   The existing barrel has a little wiggle but I'm not sure that the recoil spring can make up an additional. 005".  

What do you guys think? The way I figure it I have 3 options.  

1.) Sell the threaded barrel to someone with an fnx .45 that wants it and doesn't want to wait a year, then hope gunbroker saves me with a FNP .45 threaded barrel.  

2.) Sell the threaded barrel and the gun then buy a FNX .45 tactical with an actual threaded barrel (assuming that I can get within $300 of the price of the new one this way)

3.) Get a gunsmith to fit the barrel and try it.  (Good gunsmithing available in the Carolinas?  I'm pretty sure the Anvil guy on YouTube won't want to touch this)

You could see what it costs to have the barrel fitted and go from there. Also,having the barrel fitted might also might mean a refinish,so you might want to add that to the cost(s). It all depends on what would make you the happiest, in my opinion.Unfortunately, selling the barrel might not get you very much,especially to someone with a FNX Tactical, as the barrels usually last a long time.