Steel is where it's at

The promag mount from mystic is best bang for the buck hands down.
I agree that the ARMS18 scope mount is a great scope mount, but the CASM is a new, advanced design that offers long distant shooters adjustability & solves common installation problems found with "Brookfield" inspired designs.
A few points to consider:
1. The CASM requires "0" gunsmithing: it is a true "drop in" optics mounting solution. One cannot be sure that ARMS18 clones will or will not require fitting to your receiver for example, which "possibly" means taking material off the mount to make it fit. There is a documented history of this problem.
2. The CASM is the only M14 scope mount that is
"adjustable" affording you "0" or up to an additional 30MOA (or more) of rake should you want it for long distant shooting. You cannot adjust Brookfield inspired designs in this fashion and no other M14 scope mount in the world offers this level of adjustablility. It is a proprietary design to the
M14.ca CASM.
3. All CASM series scope mounts are double-locked having the largest fasteners of any M14 scope mount sold in the world. The CASM will never shoot loose. (A properly installed ARMS18 won't shoot loose either but it can/might be more difficult to set up).
4. There are no issues with stovepiping on the CASM series scope mounts so there is no "tweaking" to do whatsoever, i.e., there is no need to swap your rifle's extractor, ejector and springs to USGI to make it work for example on some rifles. There is a documented history of this problem with ARMS18 mounts.
5. The fact is some M14's may never work right with the new style Brookfield inspired designs unless you spend extra money, take the time to do proper modifications to your rifle yourself or pay a gunsmith. Each rifle is different but no matter, every M14/M1A/M305 etc., can seat a CASM mount right out of the box with nothing but simple tools.
6. There is no history of the CASM series scope mounts ever shooting loose. There is no history of the CASM series scope mounts failing, ever and so far, there are no documented problems with the CASM despite having mounts in every CAD province and every US state excluding protectorates.
7. The owner of Sadlak Industries LLC informed me once that given the material differences, Sadlak aluminum mounts will not shoot loose, will hold zero and are
"as reliable as their steel models." I would argue the same for our CASM series: material choice suits the advanced design and the mount is, well, rock solid and for $140 it seems to be a good Canadian value considering these points of comparison.