I've got three .22 rifles, two of which I have tested.
The tightest grouper, as I have thus far determined (more on that anon) is my stainless Ruger 77/22.
I knew these were reputed to be inconsistent groupers but I liked the appearance and overdesigned strength so much I still wanted one.
The proper approach would have been to test with a known accuracy level ammo (Federal Gold Medal mid-late '90s vintage), assess any specific issues stopping me from 50 yard MOA, and step by step go from there.
Too sensible, so I took a more broad brush (and expensive) approach.
I had recently bought a Volquartsen 10/22 when Vq was still building them on Ruger 10/22s. From the first time out of the box, it was easily <MOA off the bench.
So modifying my 77/22 would center on Vq parts. I installed a Vq trigger which Vq said would result in a 2 - 2.5# pull. I also added a trigger shoe to give a wider (thus lighter feeling pull) surface. I next put on a Vq muzzle weighted barrel, which would require no modification to the stock. I asked Vq if their 10/22 pillar bedding system kit would work with the 77/22. They said it would, and suggested bedding only the front of the action. I also sent the bolt back to CPC in Ct to have it shimmed.
When I buttoned it up, I noticed the barrel floating in the larger laminated stock channel. Since some rifles shoot tighter floating, and some shoot tighter supported, I decided to test it first floating, then support later if necessary. It is still floated.
Using a 3X9 Leupold scope I bench tested it at 50 yards. The first three shots were touching each other in an overlapping cluster, not strung out. I then got called away to work with another shooter. By the time I returned to it the light had completely changed, so that ended the test.
But that had convinced me that this rifle was well <MOA, which was my goal. Once I have established a rifle meets my objective of <MOA, I don't go any further, because I have no further interest, the anon part I referenced above. Had I wanted to pursue ultimate grouping ability, I would have put on one of my longer scopes and gotten a supply of (more expensive) target ammo known to group well in Vq (Lother Walther blanks) barrels. But I was satisfied with where I was.
The last one is a Winchester Model 52, the latest iteration manufactured by Miroku. I was just starting to break in the barrel, prior to testing, when other activities and obligations got in the way. This would have been a longer road because I did not know what the Miroku barrel preferred, whereas I had that info about Vq.
At any rate I did not do further testing. Frankly one point limiting was/is the absolute perfection on this 52. I know Miroku is known for its craftsmanship, but the workmanship and finish on this rifle still amazes me. I would not even want to get a fingerprint on it. It is a safe queen, subject to change only if I so desire. If grouping ability is anywhere consistent with visible perfection though.......