I've been interested in Paradox-Bored guns for many years and the opportunity to have some made on relatively cheap but serviceable NEFs arose, and since I am not getting any younger, I went for it.....
www.deltagunshop.com in Coleville, Washington state did the re-boring work, and have been doing work for Hamilton Bowen as well.
First I had an NEF .44 magnum back-bored leaving an inch and a half of .431 diameter rifling at the muzzle and a nominally .452 smoothbore back to the new chamber cut for .45 Colt/.410.
Accurascy with a lead bullet factory loads, or handloads using Hodgdon's Triple Seven powder and an altered LEE .45 Minie bullet mold (altered to flat-base) of 300+ gr. weight shot well and consistantly. (Minute-of-paper-plate @ 100 yds. offhand :-)
Since blackpowder .45-90-300 ballistics were nearly identical, I figure the handload would be a deer/blackbear killer at ironsight ranges.
Shotloads were not so good...I think more due to the limitations of .410 and tiny ammount of shot than any "flaw" in the gunwork.
Both the NEF and T/C pistol barrels I have had done patterned aprox impr.cyl., and had a sure kill range on smallgame of 20 yds. or a pace or two further...
The 1/3 oz. CCI .45 Colt shotloads, or duplicate handloads appear to be "good" for about 12 to 15 yds. Quieter and very useful in thick cover & close ranges...)

I have since bought the tooling to have a 16ga. done on a rifled NEF heavy barrel 20 ga.
The re-bored gun patterns 7/8 oz loads more evenly than 1 oz. ones thus far, in what I'de say was impr.cyl. or mebbe even a "loose" modified pattern, which is very encouraging.
The NEF gun I chose to modify was a "Youth" model, with 22" barrel and 13" LOP.
It has a scope base and high comb stock that I will leave on while working up ball & bullet loads, and then plan to remove (hoping that the drilled holes don't weaken the breech area liek postage stamp "perforations" ).
Final plans for sights will be Ashley Express white bead front and shallow "V" rear mounted with about one foot of sight radius between front & rear sights.
Also, a regular shotgun stock with lower comb and more drop at heel will be installed, since most of my shooting is offhand.

I will be trying the 16ga. Paradox Gun first with .65 cal. roundball.(440 gr./1 oz.)
Barrel is .63 at the rifled muzzle section and .655 or .660 at the smooth-bored section.
I plan on loading with Triple Seven and using SPG lube, & brass cases w/ Circle Fly wads for brass cases (14ga.?)

If the ball does not work as well as I hope, where can I get pix of what a Paradox BULLET is supposed to look like?
I don't recall the twist ratio, but does anyone have reccomendations for weight of a Paradox bullet for 16 ga.?
Also, are there any molds currently being made and by whom?

I'me glad I'me here at Nitroexpress, where I was told I could find info. on Paradox Guns by soe of the fellows at Australian Hunting Net! :-)
Most "shooters" don't understand the attraction of a versatile gun for short-range woods hunting/stillhunting, that will also shoot birdshot well with no choke or barrel changes...Just swap cartridges to suit the game...
I've shot deer well over 200 yds. away a few times, and that was OK, but the ones I remember the most clearly, even from a half century ago, are the ones where I got close and it was a matter of FEET, not yards...
Most of my deer have been shot at 70 yds. or less, and I think a Paradox Gun will be ideal for the kind of hunting I most enjoy, as well as for blackbear and brash mtn. lions that show up around here occassionally.
Mebbe a moose up north someday....?
If I am loaded for grouse or hares, all I have to do is slip in a different load and I should be "good" for 100 yds. or so. (As far as my eyesight will allow me to shoot reasonably....)
Paradox seems to me to be an excellent choice for what I'de call "iron sight ranges" of not over 125 yds.
"Grouse-to-grizzlies", LOL!
I've still got alot to learn, obviously.... :-) , but it should be a great deal of fun doing so.

Thanks!
Dave3220