... you got it, them dove tail block thingys! I love technical jargon! lol
I've had good luck with them on several rifles, but I've seen where others weren't as fortunate.
I had a 760 once that I shot a 146 out of 200 at 10 meters offhand with BB's. I had to use it for parts to fix some other guns, but I saved that barrel!
I plink, therefore I am.