Tom,
I would not feel like the lone arranger with how some no.1's shoot....
Some are quite fussy it seems. I too have read on the internet about enhancements for accuracy, sure a lot of hard earned facts huh?
As you know the first thing about a No.1 is its cosmetics, a heavy target gun it is not accuracy wise. Not sure about the type of groups you expected, we all seem to expect 1/4" groups nowadays; which probably is quite a feat with a no.1.
One thing you have going for you is that you have the heavier, stiffer barrel. The No.1A's can be trying at times. If it was mine, I would pull the forearm; and shoot it off bags. If it does not shoot reasonable without the forearm, no need in fooling with said interface. The other thing about no.1's is that their trigger is a multilink system. The old three screw triggers had an adjustment for sear/hammer engagement; Ruger removed that adjustment with its later 2 screw(pull and overtravel only) trigger which I am sure your new one has. The lock time of a no.1 is pretty lengthy; so try to follow thru your shot.
One thing cheap to do is to use the o-ring on the forearm screw. An old article by Keith is where I heard about such. However I never could figure from the article just exactly where the o-ring went. I knew it went over the forearm screw, but inside or outside of the forearm? I have never tried outside, but have had fair success with the o-ring between the hanger and the forearm over the screw. This floats the barrel from the forearm to some degree. The new drill/tap of a screw thru the forearm hanger onto the barrel thru a pad, never did much for me on a regular basis. Just my experience, others may have differing experiences with such.
Can your reloads touch the rifling? Some Ruger chambers have long throats. Is the bullet matched to the rifle's twist? Perhaps handloading might help out, not sure on all of that; not all are into handloading.
Over the years, I have the habit of rebarreling the ruger no.1's that I own, put on a Shilen, Hart, Lilja blank and things got better for me. Will they for you? You pays your money and sees what happens.
I suspect that your trigger pull is pretty heavy. The Austrian set trigger system($$$$$) takes some of that out of the equasion. All in all, one has to manage the shot/followthru with the No.1.
I have read and so noted on some of my rebuilds, that when one pulls the quarter rib off the factory barrel; it can show a lot of warpage; almost like tensioning of the rib metal. Not all have done that for me, but some did. I have tried to straighten some of them, some came out straighter after a flexing; had one snap in two.
Shooting the no.1 is a real trip once any bugs are worked out, enjoy it.