[mateba]

You might want to consider tamper evident thread paint, not threadlock. Its not hard to get off, but its obvious when its been moved. You could have a ref initial it with a fine point sharpie after its dried. I use it on my reg from time to time. You can find tubes in assorted colors on mcmastercarr for $5. Have you tried calling Palmer Pursuits?

 

[mateba]

I don't see an issue with it, but I doubt the guys at your chrono station and I would see eye to eye. Palmer's is correct though. A set screw would be harder to manipulate. You would need an allen key but by having one would also make it easier to use the tamper evident paint too. I was wrong about the price though, 1/2oz tubes are under $3. http://www.mcmaster.com/#tamper-evident-paint/=dy7a3p

Of course a nut on the new set screw could be used as a jam-nut which would be just as good as any tourny lock. You would need two tools and more TE paint to change you reg.

 

[mateba]

Take a nut that threads on the new set screw and use a wrench to get it more than hand tight. This will prevent the set screw from going any further into the reg without taking the nut off first. Use a little thread paint for obvious reasons and I don't think an OP host would have a problem. At least you took the time to put up with their hassle. They treating other GBBR and PTW users the same?