Back in my younger days when I enjoyed taking everything completely apart and putting things back together I grabbed my Ruger 77 and went to work on it. I remember taking the extractor plunger out and stripped the bolt down to bare metal. I remember fighting to get that plunger back in properly but if I remember right I ended up using a small nail to hold things in place as I placed the pin in.
With the nail being smaller than the hole in the bolt it went in very easy and then as I put the pin in I just manipulated the nail, plunger, and pin until it all went back together.
There were a few items that I pulled apart in those days that I struggled with for quite a while, but I always managed to get everything back in working condition without a lot of the actual tools that were recommended to do the job. This was with automotive engines and transmissions also.