This is a mystery to me. I have searched high and low for information on the Phoenix Sure-Shot but to no avail. The action, locking  mechanism, ejector, and screw placement on the frame look identical to an early Stevens No. 16 Crack-shot, though made for a pistol grip. The bump on the lower tang is cast as part of the frame to support the mainspring in this curved configuration, i.e. I don't think this was a modification of a No. 16 frame, it was cast this way. The stock is unusual for a Stevens, looking somewhat like that of a Kentucky rifle. It has been machine-milled to fit the rifle, not hand fitted/carved. Note there is a channeled recess in the stock beneath the top tang where the sliding thumb safety would have been, if it is indeed a Crack-Shot. Length of pull is 14-1/4 inches, making it more of an adult-sized rifle. The barrel is 20 inches with a nickel front sight. There are no other stamped marks on the rifle other than those pictured here on the barrel. The font and flared asterisks are also similar to those on older Stevens barrels.  Could it be a crossover rifle between the discontinued Stevens Sure-Shot and the No. 16 Crack-Shot that followed, or even a prototype? What are your thoughts? ~Dennis

Another photo...

My guess is that your rifle was made by Stevens for a hardware  company with the trade name Phoenix sure shot, and is a Crackshot  #16. I believe your rifle was customized with nicely done engraving and the tangs were bent for a custom buttstock. The cast boss you point out with the pencil is where the factory mainspring would be held in place, so you have a custom mainspring also. The early Crackshot #16’s had a safety and were chambered in .22 short only.

Thanks, all, for the input. I also thought Phoenix may have been a trade name and researched names used by firearms companies from 1890 to 1930. I found nothing except for two companies that manufactured percussion revolvers using that name. I don't believe the frame was converted from a No. 16. On closer inspection, the mainspring screw hole on the lower tang is placed rearward about 1/2inch further back than the hole for the No. 16. This was to accommodate the longer straight main spring needed for the new grip design. There is no evidence that the original screw hole had been welded closed and reworked. The frame was factory drilled and cast with the mainspring bump as you see here. (A curved main spring from a No. 16 is inoperable in this pistol grip configuration). I am thinking this is an unknown Stevens model, it was purpose-built, and was an experiment or a fancier version tried before settling on the on the No. 16 Crack-Shot name. I've only been able to find one other photo of a Phoenix Sure-Shot and it had the straight grip, was nickeled, and given a presentation head-to-toe acid etched "engrave" job (like what's found on old Civil War Officers swords). Even the the barrel was etched. I am learning as I go. I do appreciate your comments. I could take more pictures if that would help. (The engraving is mine, by the way.) ~Dennis

I see your rifle has the slot in the upper tang for the safety, and has   the correct hammer for the safety. It looks like the cast boss in the upper tang for the safety has been ground off. 
In James Grant’s Boy’s Rifle book, he mentions two #16’s being marked Keystone and The Marvel, that have no Stevens markings.Right now there is a # 16 on gunbroker marked the.22 Spencer, but is quite rough.
Your rifle is interesting, and agree that the engraving is very well done. You are very talented!

Thanks for all the great information! It is much appreciated. Boy, I really thought I had something novel, I had to call my Porsche dealer and cancel my order, lol. Merry Christmas to all. ~Dennis

Hey Bill, 
Thanks for the nice words. I've decided to list this little rifle on GunBroker at a relatively
low starting point (from an engravers point of view).

Thanks again and Merry Christmas,
~Dennis