What I have used
T20 torches ( be aware there are many that can be listed as a T20 ).
They are copy of a wolf eyes torch and used for InfraRed illuminators by some a few years back .
you can get them in white , red , green ,yellow (im sure you can ) and IR for night vision use .
you could buy them in 3 mode (high ,medium and low power) or single mode
I have one that I swap the Pills (led parts) from either red to IR . they can be zoomed in or set to flood beams .
These are not so easy to find now as there is newer versions .
They are also available with the bigger 50mm lens or the 67mm lens . bigger the lens = longer range and smaller beam when fully zoomed out .
I have a T20 and a T67.
Newer version of the above
The newer version has an easier to swap pill and even the head size can be changed to give more range .
you can find these in many shops online like ludicrous lumens ,the torch factory and so on .
You can also find them on Aliexpress under the model name of the torch rather than what the other sells call them .
The uniquefire UF 1508 is the 38mm head size that others call the T38 . It has the same size lens as the old T20 I mentioned above but it has an easier to swap pill .
this pic shows what you can with the one body of the torch but all the different size lenses http://images.night-vision.org/l-m/u...38-t50-t67.jpg
The T20 and the UF 1508 can be used with a rat tail switch you mount on your stock too so you do not have to switch the torch on by the end cap.
If you do buy a torch that uses a 18650 battery ,be aware that Almost all ultrafire or any battery with fire in the name will be fake . Any 18650 battery over 3400mah is fake although there is some genuine 3600mah.
so factor in a decent battery and decent charger into your costs if going for the above torches .
I use an adjustable torch mount on my rifle as it allows me to adjust the beam depending on how zoomed in it is . I have mine set so that it is not directly on the quarry but it still show eyeshine after I have used the full beam to identify the quarry .
Leds that show a white light can be used with a filter but it cuts the range as the led is putting out mainly white light rather than the full spectrum of light like an incandescent light does . If you are only shooting short range then that may not be an issue for you.
Other people will have their ideal torch and they will give advice .
There is many more out there that can be used but the above is what i have used and continue to use
Mounting the torch
I use one of these adjustable mounts https://www.ant-supplies.uk/scope-si...or-mounts.html
and one of these on my scopes depending what rifle im using
https://www.ant-supplies.uk/scope-si...ory-rails.html
. you can buy them cheaper from E-bay or aliexpress but you will have to wait a long time in some cases as they come from China
Just be aware that some torch bodies depending on the brand may have a thinner/ thicker tubes and some mounts wont fit .
My T67 has a 30mm body as its uses a 26650 battery rather than a 18650.
Russ Douglas on the BBS has a torch review coming up soon and that is one that some people have been using .
KL41 white/red/green/IR -LED torch.