Although, I never had Security Six, I always wanted a nice one, stainless, 6", with scalloped right shield (later production!?):
From what I found, this revolver is almost indestructible. Some ranges reported as much as couple hundreds thousand, or even more. rounds without breakage. I doubt that all ammo fired was full power 357 magnum, but even with 38 Special ammo, it's still remarkable durability.
To my disappointment, today i stumbled upon a post on another forum that poured cold water on my excitement about Security Six:
"...One of the major flaws of the Six series was the yoke-mounted gas ring. Bill Ruger was personally aware of this and was known to specify special production of cylinder-mounted gas rings to fill law-enforcement contracts. Of course Dick Baker was aware of it too, and marveled that S&W had changed the 19 from a cylinder-mounted gas ring to a yoke-mounted ring. He realized this was a step backward. One of the first engineering changes he made when he arrived at S&W is to put the gas ring back on the cylinder, redesigning it to address an issue where it would sometimes come loose. This was introduced with the 19-4 and 66-1..."
https://www.thehighroad.org/index.php?threads/that-one-go-to-357.897604/page-4 , post #97
I searched further and found cross section of Security Six:
Also, see cylinder:
Here are two yokes, one has a groove (not visible on cross section above), other doesn't:
Looks like that right yoke is the same as one on cross section.
Author of above post mentioned lack of cylinder gas ring as a "flaw", and that Ruger did make some revolvers with cylinder with gas ring. I've heard that cylinder without gas ring on Remington 1858 is a substantial issue, but Remington is revolver for a black powder, that has a lot of residue. Security Six is a modern revolver, designed to be used for smokeless powder. The only potential problem I could see IF(!?) derbies from lead bullets and lubricant are getting into cylinder central hole.
Just out of curiosity; are later Security Six models equipped with cylinders with a gas ring?

From what I found, this revolver is almost indestructible. Some ranges reported as much as couple hundreds thousand, or even more. rounds without breakage. I doubt that all ammo fired was full power 357 magnum, but even with 38 Special ammo, it's still remarkable durability.
To my disappointment, today i stumbled upon a post on another forum that poured cold water on my excitement about Security Six:
"...One of the major flaws of the Six series was the yoke-mounted gas ring. Bill Ruger was personally aware of this and was known to specify special production of cylinder-mounted gas rings to fill law-enforcement contracts. Of course Dick Baker was aware of it too, and marveled that S&W had changed the 19 from a cylinder-mounted gas ring to a yoke-mounted ring. He realized this was a step backward. One of the first engineering changes he made when he arrived at S&W is to put the gas ring back on the cylinder, redesigning it to address an issue where it would sometimes come loose. This was introduced with the 19-4 and 66-1..."
https://www.thehighroad.org/index.php?threads/that-one-go-to-357.897604/page-4 , post #97
I searched further and found cross section of Security Six:

Also, see cylinder:

Here are two yokes, one has a groove (not visible on cross section above), other doesn't:

Looks like that right yoke is the same as one on cross section.
Author of above post mentioned lack of cylinder gas ring as a "flaw", and that Ruger did make some revolvers with cylinder with gas ring. I've heard that cylinder without gas ring on Remington 1858 is a substantial issue, but Remington is revolver for a black powder, that has a lot of residue. Security Six is a modern revolver, designed to be used for smokeless powder. The only potential problem I could see IF(!?) derbies from lead bullets and lubricant are getting into cylinder central hole.
Just out of curiosity; are later Security Six models equipped with cylinders with a gas ring?