Ever since I acquired the Atlas CAL bipod, I have been running it with a Really Right Stuff SOAR BTC-Pro adapter in order to run the Atlas bipod on an Arca dovetail rail.
The Atlas CAL is a great bipod and the RRS SOAR BTC-Pro is a solid two-way adapter that will allow use on both Arca-Swiss style dovetail rails and a Picatinny rail. It is a screw knob style clamp and I feel that screw knob is actually the more versatile option over lever-release clamps because it is more universal with varying tolerances of Arca dovetails and Picatinny rail.
Screw knob clamps are slower to use in some regards because you obviously need to turn the knob to tighten and loosen, and you may have to break position more significantly if you need to make and adjustment (move the bipod forward or aft).
Right around Jan/Feb of this year, RRS SOAR announced their ARMS-LR Bipod Clamp which is the lever release clamp for the Atlas bipod and any ARMS-17S based system. Being a longtime user of RRS products (been using RRS camera L-plates for many years), I decided to acquire a RRS SOAR ARMS-LR Bipod Clamp.
It exudes the high quality you expect from Really Right Stuff. The most critical feature of the ARMS-LR Bipod Clamp is that while it is a lever release clamp, it is also a dual system clamp supporting both Arca-Swiss style / RRS dovetail rails and Picatinny rails.
Pretty much all lever clamps on the market will be compatible with only one rail type because making a clamp that will fit the tolerances of two different rail types requires a lot more engineering. But RRS has already made headway into this realm when they released their SC-LR clamp several years ago.
The ARMS-LR is noticeably larger than the BTC-Pro, but the ARMS-LR is actually streamlined vertically.
The screw knob of the BTC-Pro breaks the bottom plane of the foreend of many chassis systems and if you have weights or other devices on the sides of the chassis foreend, this can be problematic for the BTC-Pro.
The current price of the ARMS-LR is $118 USD and is significantly more expensive than the BTC-Pro at $70 USD. Many folks will balk at the price of the ARMS-LR and may opt for the BTC-Pro.
In my opinion, the BTC-Pro is probably the better option of the two if you are budget conscious and don’t need a lever release clamp. But if you need a lever release clamp for a specific use case, then you will need to pony up for the ARMS-LR.
Caution: If you are shopping for an Atlas bipod, I discourage getting one from Amazon or eBay. There are too many counterfeit Atlas bipods and unscrupulous sellers targeting Atlas bipods. Buy direct from B&T Industries (aka Accu-Shot) or one from one of their authorized dealers (e.g., Brownells, Inc.)