You torqued the bolts too tight.I went out to the range yesterday and shot 100 rounds through my 581 series Mini. I did not experience any malfunctions at the range so when I was done, I packed up and went home. When I sat down to clean my rifle, I noticed that two of my gas block screws had sheared themselves apart!
My original thoughts were that I over tightened the screws since I have re-torqued the gas block, but that was last summer and I have since put many rounds (800+/-). The ammo I used was 20 rounds of PMC Bronze .223 55gr. FMJ, 40 rounds of American Eagle .223 55gr. FMJ and 40 rounds of Herter's (repackaged Tulammo) .223 55gr. HP. I don't think that any of that ammunition should have been "too powerful" for the rifle.
Has this happened to anyone here before? What do you all think caused this? What do you think my next course of action should be? Should I send it into Ruger for repairs or should I just order some new screws and install them myself? Thanks in advance!
The gas block heated up faster than the upper. The expansion of the lower stretched the bolts beyond yield strength.
It just took time and a couple of heat cycles to stress the bolts to failure