Good grief! I can't believe I missed this post!
There is no reason for a Ruger #1 not to shoot well. Some of the very early ones had questionable barrels since they were outsourced by Ruger, but today's barrels are first rate. There are a few tricks that can make them even better. The article referenced by Chambered221 is a good one and I agree with the methods described. There is one other thing that I routinely do when I find one that just doesn't quite measure up.
The so-called vertical stringing “issue” referred to by so many shooters in the past can be traced to an innovative design feature that Bill Ruger incorporated into his original plan. The forearm and mainspring are attached to an extended hanger protruding from the front of the receiver. Though excellently engineered for strength, stability and manufacturing ease, it also is the culprit concerning most of the charges of vertical stringing of shots. With the forearm, spring and hanger in contact upon firing, all parts try to vibrate at a different rate. Since this rate is uncontrolled, it cannot always be duplicated from shot to shot. This of course means that each bullet leaves the bore at a slightly different angle and results in either vertical or horizontal stringing of groups, depending on the particular rifle. The cure is relatively simple; dampen this vibration scenario and provide a bit of needed barrel support.
The good news is that this can be easily corrected in one of three ways:
The first method is to install a Hicks Accurizer (available through Brownell's) that attaches to the front of the hanger and adjusts the barrel/hanger tension by means of a tensioning screw. Installation is relatively easy, but a fair amount of inletting of the forearm and glass bedding is required.
The second method requires either the services of a gunsmith or machinist to drill and tap the hanger just in front of the mainspring retainer. A 6 – 48 tpi setscrew is screwed into the resulting hole to contact a small steel pad placed against the barrel. By careful adjustment, the optimum tension setting for a particular rifle can be found. Again, glass bedding is essential.
The third method is a result of my habit of both trying things for myself and not having access to a gunsmith that I trust with my rifles. This method only requires a selection of small steel nuts or shims approximating the width of the hanger and of varying thicknesses. By wedging a shim of the appropriate thickness between the hanger and the barrel to create the required tension, accuracy is enhanced immensely. This method is cheap, easy for the average gun-owner to perform, requires no permanent alterations to the rifle (other than bedding) and works perfectly.
This third step is also a good way of seeing if you need to consider either of the first two:
The first step, as in all work with a firearm, is to make 100% sure that the rifle is unloaded!
Next, remove the forearm while being sure not to lose the forearm take-down nut.
Using a wide-bladed screwdriver (wrap the blade area with tape to protect the rifle's finish) gently spring the hanger away from the barrel. Insert a shim near the tip of the hanger to create a tension wedge exerting enough tension to hold it firmly when you allow the hanger to return to its former location. This additional tension will hold your shim without fear of movement.
How thick should the shim be? Only you can determine that for your particular rifle. I always start with a thickness that springs the hanger enough to create a gap about .052" (about the thickness of a dime) greater than it originally was and use thicker shims if shooting shows that they are needed. This thickness also generally creates the proper clearance between the barrel and the forearm to, in effect, free-float the barrel.
An easy way to tell how much tension is required is to shoot the rifle without the forearm and try various thicknesses while testing. All shooting should be from a bench and only the forearm hanger should contact the bags. If you elect this method, be sure to either remove the forearm take-down nut or securely tape it in place. It can be lost very easily.
Once you have determined the proper tension and installed the wedge, a few drops of one of the new "wonder" glues can help keep it in position even if the forearm is sprung slightly as when using a sling.
Now your attention needs to return to the forearm itself. In order to prevent the forearm from rocking on the hanger, a little glassing is called for followed by floating of the barrel to ensure that no forearm contact exists. At the same time you want to make sure that the forearm has not been made to contact the receiver. Just a tissue paper thickness of gap is all that is needed between these two surfaces as long as it stays consistent.
The first picture shows a 100-yard group fired from a new Ruger #1B factory original.
This picture is at the same range, same loads and under similar conditions after the above work was done.
I have never owned a Ruger #1 that wasn't capable of shooting sub-MOA groups with a little care and tinkering. You have a very good rifle there, just might take a little experimentation!