I have a remintong 700 5r and it's completely stainless. I took off the factory bolt knob before I thought about this but - will 50/50 soldering (lead/tin) stick to stainless? or should i find an alternate means of attachment.
lead/tin solder won't do it, it's definatlly not strong enough even if it does stick. Like was mentioned above brazing or tig is the way. If brazing clamp a vise grip on the handle below where you are working for a heat sink. If you get the handle to hot it can weaken the handle to bolt body brazing. This must be the Tac-Ops knob kit. Tig welding will be much nicer if your not going to paint the bolt,however it will require making a new stud out of appropriate stainless material.
old topic, but just a little revival. If you are going to solder it then the solder needs to be at least 45% silver. There is also a special flus you need for that. There is also a technique as you do not put the flame directly on the flux. The metal needs to be heated to where its almost glowing in orderfor the solder to flow and take to the steel. Also, using a wet rag or thermal paste/gel placed at the bolt/handle joint will keep the heat from messing with the brazing there.