Fired an E1 that was very professionally converted to selective fire. Full auto fun with an 8 round mag doesn't last long...
I "professionally converted" my very first E1 in early 1960s when we lived just at the edge of Indianapolis, a couple of miles from the Speedway 500 track.
I only knew basically that it could be done from what I had heard from other gun guys (no Web at that time). I took out the trigger assembly and studied it for about 15 minutes.
Went into the garage and got my 1/4" drill, picked out a bit I thought would drill a hole to accomodate the large nail I got while out there. Decided where the hole had to go and drilled through the receiver completely.
I then reassembled the rifle, cocked the action, pulled the trigger and the bolt flew forward. Without releasing the trigger I re-cocked the gun. The bolt stayed back.
I then stuck the big nail through the receiver and repeated the above steps. This time the bolt did NOT stay back! I knew then I'd hit the "sweet spot" to hold the sear back for FA.
It was night time so I loaded a 20-rd mag with every third round a tracer and took it out into our back yard. Cocked the rifle, aimed it skyward and held back the trigger. A very fast BBBRRRRAAAAAPPP and I watched my tracers head out of town against a jet black sky. It was over in probably 2 seconds at most!
The nail was a handy gadget as it was suggested you might be approached by someone in authority while afield, and asked if they might check your rifle. At that point you simply slip the nail out, toss it into the bush and hand over the rifle...
Once I knew I could do it, I never converted another, and I've owned at least a dozen E1s, maybe more, since then.
I'm offering one of my extra 20-rd mags at online auction right now and it's still at $185 with a couple of days yet to go.
Best regards ~ ~ ~ mauser