Wisconsin Trigger Company M-K IIA2 Trigger

Some people spend a lot of hard earned money on aftermarket gun parts to squeeze more accuracy out of their AR-15 rifle. Pricey barrels, tricked out stocks, fancy receivers and other mods can play a crucial role in ergonomics, harmonics and other factors that affect the bullet traveling down the bore, but they aren't nearly as important as the trigger mechanism. Anyone worth their salt in the shooting realm will tell you the trigger can make the difference between a good group and a bunch of excuses. The finest barrel on the market won't do much good if a laborious trigger pull causes drastic variation before the shot breaks and the bullets leaves the muzzle. Any deviation, even by a degree or two, can throw the shot off target.

The AR-15 trigger has seen a huge jump in design and engineering advancement in the last 57 years. Most shooters would have a hard time holding consistent 1 MOA groups at 100 yards and further using a gritty, stiff single stage trigger. Precision shooters require a crisp break that prevents the shooter from exerting any unnecessary forces on the rifle during the moments when the trigger is pulled, freeing the hammer to swing into the firing pin and detonate the primer. Even the microseconds when the powder is ignited and the projectile travels down the bore, excessive movement from trigger overtravel or continued pulling force can move the barrel off the point of aim.

Thankfully improvements in sear disconnects, spring weights, and user adjustability have turned the old Armalite rifle design into a strong contender on the range for competitive marksmanship. Competition shooters often select match grade two stage triggers for their precision builds.  A two stage trigger has a first stage "takeup" of average pull-weight that comes to a stop when pulling slowly. This wall allows the shooter to breathe, focus on the target and stage the second step, a hair more of pressure that releases the hammer. The overall force needed to fire is the same between a two stage and a single stage trigger of the same weight rating, but the two stage requires much less pressure in the final stages before the actual break

The Milazzo-Krieger Two Stage Match Trigger System, or M-K II is the first patented two stage match trigger system for the AR platform. If you're wondering where you've heard of it before, you may have spent some time at Camp Perry. The M-K II has been widely used in M-16 rifles competing and setting records in the US Army Marksmanship Unit (USAMU) since the early 1990's. Production stopped in the mid 1990's, however the Wisconsin Trigger Company began to offer the M-K II trigger on its 25th birthday using all the original tooling and fixtures. The first generation of M-K II triggers required some trimming of the metal at the back of the trigger unit to adjust overtravel, but luckily the Gen2 model resolved the need for unpleasant grinding.

Comparing the M-K IIA2 trigger (left) and the Rock River Arms two stage trigger (right) you can see the RRA disconnector is preset and not adjustable.

Left: M-K IIA2 trigger. Right: RRA trigger

The next generation of the M-K II, designated as the M-KIIA2 was designed with the tactical shooter in mind. The Wisconsin Trigger Company implemented a user-adjustable second stage release via an allen screw that moves the disconnector up and down. This allows the user to find the precise moment where rearward trigger movement contacts the disconnector and forces the second stage to break on their rifle, which is called the "Zero Point." They also incorporated a factory set over travel, forward trigger overtravel, and small pin and large pin Colt styles.

Left: M-K IIA2 hammer. Right: RRA Hammer

Installing a AR trigger thats not a singularly housed drop-in component can be intimidating if you haven't done it a few times, but the instructional booklet and the online videos on the manufacturers website help clarify the process. Basically you remove your existing trigger components, install the M-K IIA2 trigger first, then put the MK-11A2 hammer in. The M-K IIA2 has a redesigned disconnector (the wedge shape that forces the hammer to slip away from the trigger's sear) that moves up and down with a simple screw, and provides a faster hammer reset (AKA faster shooting).

You need to remove the safety selector to properly install the trigger, so just loosen the pistol grip enough to pop it out temporarily.

The supplied trigger and hammer pins were tight enough to warrant using a hammer and punch. I don't see them walking out anytime soon.

Tightening the screw all the way down moves the disconnector downward and out of the way, removing the second stage of the two stage trigger pull alltogether. Backing the screw back out will re-establish that second stage contact with the disconnector and increase the pressure needed to achieve that break. Following the instructions, you delicately and patiently keep adjusting the screw up and down while pulling the trigger/manually resetting the hammer until you find the precise moment of contact where a mouses breathe could set off the second stage. Then you must back out the screw by approximately 3/8 of a turn... this is the factory recommended setting for adequate safety. I myself felt that 5/16 turn was more preferable. Then all you do is back it out 4 full turns, apply a thread locking compound, and retighten 4 turns back to your personal setting.

Finding the "0" point is tedious, requiring minuscule increments of tightening/loosening until you barely first feel contact with the disconnector.

I used a paint pen to mark an indicator dot, which allows you to back the screw out precisely for the final position, and then in and out again for the Loctite application.

I used the tip of a small narrow phillips screwdriver to apply the blue Loctite to the disconnector adjustment screw... its a tight space so this was the easiest solution.

But that’s not all. The M-KIIA2 also comes with three varying weight disconnector springs. They are colored red, white and blue (the blue spring comes factory installed in the trigger) The white spring is the heaviest at 5.0lbs, whereas the blue is the middle ground at 4.5lbs and the red is the lightest at 3.25lbs. I opted to leave the blue spring as is, because I was satisfied with the break I had found with my adjustments of the disconnector.

The included chart and instructions make it easy to change out the disconnect spring for lighter of heavier personal preference.

The redesigned disconnector of the M-K IIA2 also provides a faster hammer reset over traditional trigger systems. The forward trigger over travel allows the trigger to move forward after the hammer has reach it's reset, keeping trigger spring pressure on the shooter's finger which greatly reduces "trigger slapping" when shooting high speed consecutive shots.  In a 3-Gun or other competitive setting where a carbine must be proficient in both close range/fast target transitions as well as long range, slower and precise shooting, this two stage trigger system really shines.

*Note: I will post range photos in a future update. The day before a planned range trip I injured myself pretty badly. Stay tuned for groups of both slow fire at 100 yards and rapid fire at 25 yards.

Overall I was very pleased at the performance of the M-K IIA2 trigger. Installation was no different than a standard trigger, but the ability to change out spring weights and tune the disconnector with ease are huge benefits to someone wanting a more personal touch to their AR-15 trigger. Since publishing this review, the M-K IIA3 trigger was released, that retains the features of the A2 with the addition of an ambidextrous safety selector with a hole which allows to user to fully adjust the trigger overtravel.


Claim to Fame: The M-K IIA2 combines the original M-K II world class match trigger release with a high speed trigger design.

Target Market:  AR-15 owners: competition or recreation

FNBs (Features & Benefits of this product):

  • Adjustable second stage release
  • Factory set over travel
  • Forward trigger over travel
  • Available in small pin (GI Type) and Large pin Colt Styles
  • Short hammer reset
  • Redesigned disconnector
  • Quick installation and tuning
  • Includes 3 different weight disconnector springs: White 5.0lb, Blue 4.5lb, & Red 3.5lb
  • Includes Slip 2000 Lube
  • Instruction manuals & Spring Chart
  • Transferable Lifetime Guarantee

What other aesthetic options or finishes are available?:  Bronze bearing version available


"For those who are looking for an extremely crisp AR15 trigger that closely mirrors the “feel” of a finely tuned M1 / M14 trigger, this trigger might be the solution. The first stage is exceptionally clean and smooth due to a proprietary diamond-grinding process. I felt that the first stage travel was longer than a Geissele, but many guys will prefer that. Upon reaching the very noticeable and defined “wall” of the second stage, a further increase of pressure provides the instantaneous snap one looks for in a high-quality trigger — complete with a total absence of anything resembling creep or slop."
Johnny Fisher, accurateshooter.com


  • MSRP: Starting at $225.00


Bravo Comany USA or check other Wisconsin Trigger Company dealers



  • 3 different disconnector spring weights allow user to choose between light, standard or heavier pull weights.
  • Trigger and hammer pins were nice and tight (punch and hammer required)
  • Documentation/Instructions included are thorough (but videos were more helpful during the actual installation)
  • Stickers and magnet swag!


  • Standard GI trigger blade shape
  • Other components of trigger assembly are off-limits (unsafe and void warranty if tampered with)
  • Thread locking compound not included



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