I agree, but a blown primer can only be caused by pressure (as apposed to increased bolt thrust). I cannot verify it was a dirty barrel, I did not think of it at the time, but it is as likely (or perhaps more likely) an explanation as soft case heads vs work hardened case heads. I trim my brass as about half are out of spec after one firing, so it was not brass being compressed around the bullet from being too long.
I also cannot prove cleaning would have prevented it, but nor can someone else prove it would not have. There is a reason I only said it changed my mind and did not argue that others had to clean.
It is a bad idea, but I'm tempted to recreate that load, see if it still blows primers, then clean and see if it stops blowing primers. If it does not still blow primers, well we are not really any better of. If it does, but does not resolve with light cleaning, then does not resolve with heavy cleaning, then we can say for sure it was not a cleaning issue. If it blows primers, then resolves with cleaning, the question is does it start to blow them again after a while?
The real question is do I want to shoot a load that I expect to blow the primer? How strong do I think the Tikka action is? Do I want to shoot it from my shoulder, us a string and sand bags? While unlikely to be an issue, do I want to risk the rifle, scope, and stock? Yes, I know, I'm a fraidy cat.
My range time is also significantly cut into at present as I pursue other training goals, so how much time do I want to spend dicking around for a single data point.