This might be long, but could be of interest on this thread.
I have three of these great little revolvers in .327 Fed. I like the looks, the heft and they fit my had just right. In double action, for me, the sights come back to good alignment as the trigger breaks...all good.
None of them were good shooters. Over time, I developed a good wad cutter load in .32 long using Fed SP match primers, 83 gr Lapua HBWC and 2.2 gr W 221. The loads were set to depth and taper crimped after. Cases were only resized to te length of the bullets and custom case expander die inserts were fabricated by Lee and matched to the various cases that I had,
A load of 1.7 Bulls Eye was just about as good. VVN 310 wasn't bad either but the charge was so small that I didn't trust the Lee Pro 1000 to drop it consistently.
I figured that if I could get these little early three inch guns to shoot wadcuters, then anything round nose would be better. For load testing I used everything that I had, but mostly a real good from the factory Single Seven that has a two pound pull after I installed a Powers Custom hammer and trigger. I also have a 6.5 Bisley HRM, two S & W 16-4s in both barrels lengths, two four inch Colt Police positive specials, and a Single Six.
The barrels were slugged in all of these and plug gauged for tight spots.
Mr. Fermin Garza blue printed a number of cylinders in most of the Rugers.
The actions were so grity in the three SP 101s that testing was futil until I fixed that. I ended up with them coming out pretty decent using slightly reduced mainspring and factory return springs.
I don't recall that the front sights were too far off, but before the action work I sent two of them back to Ruger with bad groups shot with factory ammo. One of them had a very visible oblong oval muzzle crown and the forcing cones were undersized as measured by Brownells gauges. Both guns came back with new barrels and again, snug forcing cones.
I firelapped the tight spots out of the barrels with difficulty, so almost done. All three are much improved in accuracy, but limited by the sight radius and poor sights. The Colt Police Positive Specials shoot very small groups as is. The Single Seven wears aTwo Dogs front and a Bowen rear...nice finished revolver.
The SP 101s are going to be rigorously accuracy tested with a variety of HRM loads and Fed Magnum hand loads of known quality, plus the worked up and proven wad cutter load. This will establish a baseline for four or five Rugers. Shooting will be done at an indoor range under uniform conditions and temperature. All I have available is careful forearm resting, but I do a lot of it.
What I want to find out is if the muzzle crowns were so bad, the forcing cones are probably just as bad, and the forcing cones might not be concentric to the bores.
I have both 5 degree and eleven degree cutters, brass laps and very accurately made custom brass bore bushings to align and tweak the forcing cones into submission and find out if all of this work and expense will help these little revolvers be all they can be.
I haven't done the baseline shooting yet or the forcing cone work. I have not read yet of anyone testing barrel forcing cones in their shops in this fashion.