The switch will fit on the body. I wouldn't have too much faith in the element when the rifle recoils.
Your trying to put a flashlight host optimized for a handgun on a rifle.

It's just like a lightbulb. It's easy to have a lightbulb blow out if you unscrew it while it is on. I've had it happen more than once because I was removing a bulb behind a stall so the Stud didn't hit it with his head. (One of those situations where his attention was going to be on something else. )

It's that sharp impulse that would do the damage. Not how much the gun is going to move your shoulder.

They are so expensive because Surfire is made in US and DoD has to buy US unless there is no such product made in US.
Except for stuff like uniforms apparently. That's why Aimpoint costs twice as much as it should.
Look at the custom built stuff that doesn't have factory capacity for Gov. contract. Electrolumens has a hand made light that puts out 1000 lumens for 139 bucks it's even on sale right now for 100. Heavier threads and uses 18650s but the button is even machined. And with their contacts and quantities Surefire can't retail the C2 with under 100 lumen incan for that price????????
You can get a used P6 for 40 bucks and a Surefire LED drop-in for around 30 if you shop. That should run much longer on same batteries as well. Should stand shock of firing as well. I really should take mine out and bolt them on the rifle and test the cheaper drop-ins for durability in this role.
I use a PLS-1 mount that has a spring loaded lever to lock it on my forearm rail slides right off so I can use it in my hand.