A rifle that won't shoot- Update

[GBoyd]

I recently bought a used Rossi single shot rifle in 243. They don't have a reputation for accuracy, but I expected something around 3 MOA. That would be plenty accurate because I wanted it for a lightweight hunting rifle out to a maximum range of 200 yards

I mounted a decent 3-9x40 and took a shot at 30 yards to make sure I was on paper. When I started shooting at 150 yards, I was really disappointed. I shot a few three round groups and they were all about 20 inches across. I've never encountered a gun this bad and I don't know what to do about it. I've only tried it with Core-Lokts and I haven't tried a copper cleaner, but I can't imagine those things would make enough of a difference.

Any advice for things to try to get hunting accuracy out of this rifle? I really like how handy it is, so I'd be willing to put a bit of money into it.
 
And if nothing works, what do I do with it? I can't sell a guy a rifle that won't shoot.

[jay.sharkbait]

Do you know if the rifle was broken in properly?

[bobcat]

Are you sure the scope isn't the issue?

[Bill W]

you got something wrong and it's probably not the rifle unless you are seeing keyhole hits. 

[Bofire]

20 inch groups, there is something serious wrong with the gun, maybe safe but not a shooter. for the value of that gun it does not warrant money invested. Let it go. unless you have not checked the obvious, loose screws, etc.
just let it go
Carl

[jasnt]

Have you measured the twist?

[762Armo]

Are you sure the scope isn't the issue?

I'm willing to bet the issue is scope related.

[Alchase]

I would bring it back down to 100 yards, check your rings and scope are solid. Then try different ammo. If the results are the same with a few different ammo types. You just narrowed it down to the rifle itself.

[brew]

if your base and rings are solid then there is no way its  the ammo....any crappy factory ammo wont "group" at 20" at 100 yards....scope problem

[lewy]

I also find it hard to believe that the rifle is the problem

[buglebuster]

I ageee that its probably the scope

[Bill W]

maybe he's shooting offhand.

[ellensburgpo]

Scope or mounts

[opdinkslayer]

maybe he's shooting offhand.

was thinking that myself when i read the op

[JimmyHoffa]

if your base and rings are solid then there is no way its  the ammo....any crappy factory ammo wont "group" at 20" at 100 yards....scope problem

I don't know.  I have done a scope swap and had one rifle shoot great with both scopes at any range and the other wouldn't stay on the 2'x2' cardboard at 50 yds.