Man, if my gun looked like that I think I'd beadblast my ammo too!
My guns can't look anything like that- my guns only look used , however, I took out the crossbolt, ground and filed the end off 'til it fit flush and them replaced it, tightening the set screw down firmly against it. My GG is mainly a personal defense weapon in bear country so it usually kept around loaded with chamber empty, really not a big safety issue except for the kids. With them, I am the "bolt" and I do get "cross" when I see things that don't align themselves with proper gun respect.
Do what you want but I cant see it weakining the action. The breech block is a good 1/2" forward of the hole in question & since your replacing it with a steel plug anyhow I think it would be safe. JMO of course but mine aint in & mine aint broke.
The easiest fix is to take the stock off, clean the goop out of the set screw on the left side rear of the reciever, put the safety in the fire possition, and tighten down the screw until the safety won't move, put the stock back on....Jake
After several misfires at the bench because I forgot to put the crossbolt safety into the fire position when ready,I wanted to do something before hunting season rolled around .I can picture the big one getting away because of my forgetting to take it off of safety.I much prefer the half cock system and good safe gun handleing.I like the O-ring suggestion so I started my wheels turning.Where can I get an O-ring that size?Well.I'm not usually this smart but then I do get a brain storm every now and then so I went to the basement and dug out my bow hunting equipment box and low and behold,those little O-rings that you put between the shaft and the broadhead where looking me right in the face.They work great.Ok,go raid your archery equipment.