I have: 1)a stainless springfield M-6 .22/.410 made by CZ
2) an Armalite AR-7 circ.1970
3) a Charter Arms AR-7 Circ. 1980
4)and a Survival Arms AR-7 Circ. 1995
The Armalite is by far the best made of the three AR-7's, The bolt is crome plated and bead blasted, and the barrel is also crome lined. It is also quite accurate. I have the sights regulated for 50yrds and using CCI mini mag's shoot consistant 1" groups.Second Best would be the charter, lesser quality, Slightly more accurate for some reason, and it works flawlessly using CCI mini-mag's. I bought it at a gun show for $25.00, beleive it or not!!!! Third comes the Survival Arms; this one didnt work out of the box. After years of fiddleing it now works, and has a neeto 4X detachable scope in the case with it. They are all sensitive to cheap ammo problems. Load them with good CCI stuff and they work quite well.
The M-6 is interesting. First of all I removed the crappy trigger-guard (dont do this at home Kid's) so I could fold the durn thing like it was desighned to. Second the pin that holds it together likes to walk out, and could be easily lost. So it milled a groove in the exterior side and used a snap on retainer to keep it in place. A while back I decided to see what I could do with a pile of Rem. .410 slugs in it. Accuracy was abysmal at 50yrds. The point of impact was about 24" left and about 12" low. The rear sight is an L type apperature with a peep for the .22 and a V for the .410. You cannot change the windage on one without changing the other. So I milled off the top of the .410 sight and carefully moved the V to where it needed to be. Now it looks like this
-v----. The .22 barrel is extreamly accurate, once you get used to the trigger, which is very aquard. The leangth of pull also is a great hinderance. It is VERY short. I added a sling from an M-1 Carbine to my M-6, it works out great but you must add a front swivel. The shotgun barrel shooting shot still is dead on after my fiddling out to 30yrds.
Given the choice, I'd go with the AR-7. The utility of the .410 is kinda marginal when you add the weight of the rifle, ammo, case ect. Finding a good AR-7 is hard, but they are out there. I'd imagine the Henrey is a decent one. They seem to build decent stuff. I have never handled one though.