One thing I notice is that OP's revolver bbl only has flame cutting to the edge & face of the bbl itself at the 12 oclock position,,and that seems to have cut into the top strap right above it.
No other portion of the circumference of the barrel face is effected by any of the same type of damage.
Unlike Post #10, Lou the Welder's 357 where the entire bbl face shows the same type damage s I would expect it to.
I realize that Lou's may have a much higher round count and thus more damage to it.
But I'd still expect the OP's gun to show what damage we do see at the 12oclock position not only there,,but evenly all around the breech face of the bbl.
Could the bbl face be 'off' square with an extra wide gap at the top,,or even the face of the cylinder not be square with the bbl face?
That these revolvers do 'gas cut' is not a question. I only wonder why this one shows the issue at the 12oclock position only.
I agree that the depth of the cutting so far is very much less than the estimate given. The revolver is still safe for use IMO.
I never liked hyper magnum loads either,,in any firearm.
Excess wear and strain to get few extra fps wow factor.
I'm going to say something controversial, that I'm positive you wont believe. I'm going to say something that is going to be hard to understand. I will try.
I believe that the 12 o' clock force cone flame cuts, are due to it's close proximity to the top strap. Itself.
On an N frame like my 627, the force cone has enough meat around the force cone to vent the full blast all the way around the extension tube. All 360°. That's why the wear is shone evenly.
This is what the flame blast coming out of the force cone / barrel cylinder gap looks like on my 327 R8.
Here's a pic of my eroded force cone from my Redhawk. It finally did get worse and I sent that one in to Ruger. They said the barrel and frame were damaged beyond repair and sent me a new one. This force cone would have similar dimensions to the 627 N frame. Notice something? Even wear all the way around.
I also broke a gp100 357 magnum. I love it when people say, "Ruger's are tanks!" "You'll never break one!" "They last forever "
BS. Both the Redhawk and kgp-100 were sent in to Ruger. Both were warranty replaced. Out of the two, the Redhawk started shooting badly.
This picture shows the wear on the top first. And in the end it did get worse. Reaffirming my belief, that if the cone is too close to the top strap , the flame is more concentrated there.
On the K frames, the erosion starts on the bottoms for the same reason.
If you had seen cracks in a different position. It may have had compromised metallurgy. But in my observations, from what we've seen, they've cracked mostly in the same way. I've heard discussions about late timing, early timing issues. Hey, I dont believe this. The cylinder or stop notch either makes it in position or you have really big problems then. But I wouldn't call that late timing or early.
Again. Top strap cutting is mostly minor if at most. Unless were talking 357 maximum. Then, yes , there is an issue. But not relevant here.