Psssstttttt! Caleb wants to talk about that other accessory mounting system, the Arca rail. Great, you're thinking, just what we need! Another accessory mount to go with M1913 Picatinny, M-LOK®, KeyMod, A.R.M.S. 17S, and now Arca? Relax, says Caleb, Arca brings some extra benefits to the table. The Arca Swiss attachment system originated in the photography / video world as a means for keeping cameras securely attached to tripods. PRS shooters picked up on Arca as a mounting system for rifle bipods and tripods because of its strength and ease of use.
Arca is a dovetail system, so you put the Arca rail on your rifle - Magpul even makes an M-LOK® to Arca adapter plate - and a corresponding dovetail on the bipod easily slides onto the Arca rail. Tighten a thumbscrew or close a lever to lock everything down, NO TOOLS needed. You can attach or remove an Arca accessory super fast, and once the lock is secured, you have one heckuva solid mount because of the large metal-to-metal contact area.
The folks at Area 419 really took a liking to the Arca Swiss mount, so much that they developed their own variation called Arca Lock. Arca Lock employs pins on the accessory mount that nestle into serrations on the Arca rail for an even MORE stable mount that locks up tighter than Alcatraz. Don't worry: Arca Lock is fully compatible with standard Arca rails.
Now, let's talk about the PROs and CONs of Arca mounts...
PROs: Really fast installation, removal, and adjustment. Caleb shows us how fast you can shed a bipod from a rifle with an Arca mount. Changed your mind? You want it back? Almost as fast to reinstall that bipod. Arca mounts are extremely secure because of their much larger surface areas. There's a lot of metal in contact with metal. And Arca can be very versatile - MDT makes a bipod that attaches to an Arca rail or a standard M1913 Picatinny rail!
CONs: Arca accessories tend to be expensive, more expensive than gear with M1913 or M-LOK mounts. But with Arca you get what you pay for - rock-solid stability. Also, because of the larger surface areas, Arca mounts tend to be heavier and bulkier. So you'll want to do a little soul-searching to decide if the additional solidity is worth the tradeoff in extra bulk and cost for your needs.