Will Fit:
Winchester 94 .30-30
Winchester 92 .45 Colt
Marlin 336Y .30-30 (but it will put slight pressure on the barrel)
Will Not Fit:
Browning .348
Winchester 71 .348
Marlin 1895 .45-70
And because it was designed to fit a barrel if a mag tube wasn't an option I also tried it on a Winchester 1895 SRC .30-06 and a Savage 99 .300 Savage. It will not fit close the the forearm of these guns but it would fit just behind the front sight of the Savage and just rear of the muzzle of the Winchester. I imagine throwing that much weight up near the end of the barrel would throw off the sights (possible a lot) and it would put the light out of reach for most but it could be done if it had to.
Here is a much better review than mine:
http://jerkingthetrigger.com/2017/12/05 ... ght-mount/
Not my pictures (stolen shamelessly from the HPG sight):


I am not affiliated with the company in any way but I thought at least some of you would be interested in this. I can say I like how it breaks up the traditional lines of a lever gun but I do like having a light on a gun I am likely to grab in the night time.