Here’s what I did, and it worked for me.
I posted on a couple different airgun sites WTB 18″ or 24″ Airforce barrel.
Got tons of replies. Seriously guys have 18″ barrels that they replaced with 24″ barrels just sitting around.
I bought a barrel within the very first hour I posted, there were so many replies..
Then you can either do it yourself or find a machine shop to do it for you.
But just cut the choke off which is the last inch of barrel.
I watched a bunch of YouTube videos and felt confident in taking the hack saw to it, then re crowned it using a brass screw and valve grinding compound.
Its really not difficult at all.
Shoots great. In all honesty my 12″ choked AF L/W barrel shoots NSA’s good as well.
I started out with a couple boxes of their new machine slugs. 34gr domed & 33.5gr HP.
They shot so well in the 12″ that I wanted to add more fps so I added 4″ to the barrel.
Which was good then I added TT tophat and was able to make significant fpe gains with the heavier slugs.