Pretty tough to believe you can't get it to shoot under 4" groups. Every Ruger No.1 I have will produce clover leaf groups at 100yds. Even the 375 h&h. One of the finest shooting rifles you can own for the price tag.

I will admit they can be tempermental to just shooting all kinds of different loads through them. For example my 22-250 so far only shoots four loads, two hand loads and two factory loads. All of them under 55gr bullets of course it has a 1in14" twist. I did shim the forend on that one (myself) using brass. But even though it didn't shoot as well as I wanted but it still shot under 2" groups until I found it's sweet spot loads. It now shoots holes in holes all day at 100yds.

I believe Ruger had the middle of the road guy in mind when they built these rifles. What I mean by this is medium weight bullet traveling at faster speeds. So far from what I've found Ruger No1's shoot medium to lightweight bullets better than heavier ones. I would go back and buy some 150-165gr loads and test those against the 180's. Then if it drops under 2". Learn how to reload that's where the Ruger No.1 shines is for reloaders. That rifle concept wasn't designed for a gunsmith to tinker with it.

The basic principle of the No.1 is so simplistic that you can't mess it up much. But by chance that rifle was made on a friday after noon. I have had bought identical pistols at the same time that didn't shoot. And a whole string of 22lrs for kids that some shoot some don't. Murphy's law ya know.