Seems like it would be a good candidate.

Will the rifling stabilize the 60 grn. Aquila's?

(I posted this query in a more appropriate forum, but got no replies.)

I don't know about the MkIII, but my MkII Govt does OK with the 60gr pills within handgun range.

Not match accuracy, but minute-of-squirrel.

Shit REALLY smacks the bolt back, though.  I'm planning on getting a slightly heavier recoil spring.

Disconnector

I have a MkIII Target that I just had threaded.  It works well, but I haven't tried any 60gr yet.  My hunch is that it will work ok at close range (<20 feet) but will not stabilize much further than that.

Quoted: Will the rifling stabilize the 60 grn. Aquila's?

No, not adequately, the barrel only has a 1:16 twist.  

I don't think any factory auto pistol barrel has the ability to truely stabilize the 60gr slug.

you need a 1 in 9 twist to properly stabilize the aguila SSS.  That means a custom barrel, which would be fine except for the fact that the aguilla SSS doesnt work well in the suppressed Ruger MKII and it's variants.  the case is so short that the chamber is still full of expanding gasses when the case is extracted, and enough gas escapes to ruin the "mouse fart" effect of the silencer.  a bolt action .22 pistol is truly needed for the uber tactical ninja gun.