I just looked at your profile. Since you are in the USA, silencers are possible, but you have to get a permit. It is a real hassle and expensive too. Not worth it in my mind to go through all of the hoops. You could add a flash suppressor, but being a single shot, not sure if that is worth it or not. That is just my opinion, so take it for what it is worth. We are individuals and look for different things. As far as accuracy is concerned, the heavy barreled 223 can be one of the most accurate Handi's out there. There are some members that report less than .5" groups at 100 yards on a regular basis. Some can do it right out of the box, some need a little tweaking. You can buy a receiver and send it in for extra barrels, but I think you would be better off just buying the whole rifle. You can get the 223 in several flavors, it is one of the most popular chambers they have. You can get a bull barrel (24") in Ultra Varmint or Ultra Varmint thumb hole stock, a Survivor with 22" bull barrel. I think the 22" Ultra Hunter is a 22" bull barrel also. Those are all the bull barrel variations that are available. There are a few other variations too. The regular barrel is almost as heavy as the bull barrel. Some people mistake the regular barrel for a bull barrel. The Super Light's will not be mistaken for a bull barrel, they are rather thin, but are much lighter in weight. My avatar is a 223 24" bull barrel - 223 Ultra Varmint
IMHO, the Handi is not a bench rest gun and you will not get as much accuracy out of them as a good bolt gun. However the Handi is a premier field gun and usually has all of the accuracy you need for hunting and varmint shooting out to 300 yards. Some members use their Handi's beyond 300 yards on a regular basis for hunting. Sourdough comes to mind right away. He uses a 30-06 out to 500 yards for hunting big game ( bear, Caribou, Moose, etc) and wolves. Good Luck and Good Shooting