The first end-user adjustable compensator, the EFFIN-A, came out about a year and a half ago from Ares Armor. It was extraordinarily unique in that it could be “tuned” (for lack of a better word) by using 28 ports with matching screws. The shooter could plug whichever ports required to adjust for that shooter’s personal idiosyncrasies or weapon performance. (The Mark I has been reviewed several times, including this one on Military.com and these on Four Guys Guns.) It could also be stacked with other devices.

Now the EFFIN-A Mk II is available and it appears to have successfully improved upon the excellent performance of the Mk I.

The new EFFIN-A Mk II has been lightened and streamlined. It weighs in at 2.5oz, half that of its predecessor, and the number of ports has been reduced from 28 to 21. This would seemingly mitigate the shooter’s ability to tune the weapon, but 21 ports is still a significant number and early de facto reviews indicate the reduction does not hamper the comps performance or adjustability by any measurable amount. (Note: the set screws used in these ports all bottom out for a secure fit. They do not obstruct the interior at all, nor will they “shake loose” under repeated firing.) The EFFIN-A Mk II does not have the threaded muzzle featured in the original.

The EFFIN-A Mk II has a black oxide finish, is built from 4150 steel and is threaded ½ x 28 (making it suitable for the majority of .223/5.56 AR15 style rifles) and has the Ares Armor logo laser-engraved. A stainless steel version of the Mk II is coming down, as are additional caliber options. We have been advised by Predator Intelligence Blog that Predator Armament hopes to have Kalashnikov and .308 versions available in the next production run.

You can purchase your EFFIN-A Mk II here (it will be a pre-order for the next batch, as the first one sold out immediately); when you do so, enter the discount code PREDRECOIL to receive an additional 5% off the purchase price. This may not sound like much, but since the pre-orders are already discounted 10% you're effectively getting 15% off the price.