SGW Gunsmith
"Accipere non casus-Virga Bis"
I've owned and worked on Ruger Mark pistols for 50+ plus years now. While there's not much that can be done to improve the accuracy of these FINE pistols, they certainly can be made to "perform" much better, and in many cases, will help the operator to shoot more accurately. It all lies within the barrel and how that's been machined, along with the chamber being reamed concentric to the bore's ø.
I've tested the accuracy on hundreds of Ruger Mark pistols from those with 4-inch to those with 10-inch barrels, and with various brands of .22 rimfire ammunition from Standard to High Velocity, but never using hyper-velocity as Ruger recommends that doing so should not be done. For example: Stingers, as they produce way too much "recoil impulse energy" that causes the bolt to slam into the bolt stop pin at the top of the mainspring housing assembly quite viscously. In fact I have a bolt stop pin that I removed from a young man's Ruger MK512 pistol where he admitted using Stingers most all of the time:
That bolt stop pin is visibly bent, and the bend is obvious, but what's not to obvious is the elongated hole in the rear of the receiver that this pin pokes out of. Bolt stop pins are cheap, receivers, not so much.
When testing any Ruger Mark pistol for the accuracy it's capable of with a specific brand and type of .22 rimfire ammunition, it's paramount as much, if not all, of "human influence" be removed from the testing as much as possible. Thus, my investment in this Ransom Rest:
I've had owners tell me that they can get the same results from resting their pistol for testing on a sandbag. Until we set up their pistol in the contraption above. That's when the amazement shows up on their faces, after them shooting their favorite.22 Long Rifle rounds off the sandbag and then seeing what happens in the Ransom Rest.
Of all the Ruger .22 Mark I,II,III,and IV pistols I own, these two are indeed thee most accurate:
Here again, the reason they are more accurate than the shorter barreled versions is because the bullet spends more time engaged in the rifling so that it becomes much more stable once it leaves the muzzle, and both of these two pistols like the very same .22 Long Rifle ammunition, yet dislike ammunition of the same brand just as well. So, by golly some alike barrels do indeed like the same fodder.
I've tested the accuracy on hundreds of Ruger Mark pistols from those with 4-inch to those with 10-inch barrels, and with various brands of .22 rimfire ammunition from Standard to High Velocity, but never using hyper-velocity as Ruger recommends that doing so should not be done. For example: Stingers, as they produce way too much "recoil impulse energy" that causes the bolt to slam into the bolt stop pin at the top of the mainspring housing assembly quite viscously. In fact I have a bolt stop pin that I removed from a young man's Ruger MK512 pistol where he admitted using Stingers most all of the time:

That bolt stop pin is visibly bent, and the bend is obvious, but what's not to obvious is the elongated hole in the rear of the receiver that this pin pokes out of. Bolt stop pins are cheap, receivers, not so much.
When testing any Ruger Mark pistol for the accuracy it's capable of with a specific brand and type of .22 rimfire ammunition, it's paramount as much, if not all, of "human influence" be removed from the testing as much as possible. Thus, my investment in this Ransom Rest:

I've had owners tell me that they can get the same results from resting their pistol for testing on a sandbag. Until we set up their pistol in the contraption above. That's when the amazement shows up on their faces, after them shooting their favorite.22 Long Rifle rounds off the sandbag and then seeing what happens in the Ransom Rest.
Of all the Ruger .22 Mark I,II,III,and IV pistols I own, these two are indeed thee most accurate:

Here again, the reason they are more accurate than the shorter barreled versions is because the bullet spends more time engaged in the rifling so that it becomes much more stable once it leaves the muzzle, and both of these two pistols like the very same .22 Long Rifle ammunition, yet dislike ammunition of the same brand just as well. So, by golly some alike barrels do indeed like the same fodder.