JMT Sabre – Drop In AR Trigger

first published on October 23, 2016 by


Over the years, I have built a few AR’s from 80% receivers, several of which were polymer.  One of the most important aspects of completing the lower so that they function properly is the exact placement of the trigger and hammer pin holes.  With not all 80% polymer receivers being equal, some of them had less than ideal means of locating those trigger pin holes, resulting in less than ideal trigger function.

My wife’s pink polymer AR is a prime example of that.  When I built that gun, the trigger and hammer pin holes were off ever so slightly and it caused not only a heavier than normal trigger pull with the standard mil-spec trigger, but it also caused a very weird trigger reset and I feared it was going to eventually cause premature wear of the trigger components.  I long ago planned on eventually upgrading her gun to a drop in trigger but never got around to it, until now.


James Madison Tactical, who is perhaps best known for their excellent 80% polymer AR lowers, available in both standard AR-15 and in .308 versions, just released a new product; a complete drop in trigger assembly.   The Sabre trigger is a single stage, semi-auto trigger pack that is advertised as offering a 3.5-4.0 pound trigger pull.  The chassis is made CNC’d aluminum which is anodized silver, while the trigger, hammer and sear are all made from 17-4 PH stainless steel.  The trigger is non-adjustable, comes complete and ready to drop in, and list price is just $99.95.  Unlike some other triggers on the market, the JMT Sabre does not come with trigger pins, but JMT does sell a complete anti rotation trigger pin set, which at less than $20 was a no-brainer to me.  In the interest of producing a thorough review of this new trigger, I ordered two of them so I could check consistency in addition to function, and I just ordered them off the website without mentioning the review so I would be sure to not get some hand picked perfect samples.

A few days after ordering the triggers, the package arrived.  I opened the box and began examining the triggers.  I found that one of them was in the package with the hammer cocked, while the other had the hammer forward.  Not knowing if the one with the hammer forward had somehow got managed to drop the trigger in shipping, I checked the chassis for any damage where the hammer would have impacted it and found none.  Being the big kid that I am, I had to start playing with the trigger, so I cocked it and while blocking the forward travel of the hammer to prevent any contact with the front of the chassis, I checked the trigger pull a number of times.  In doing so, I accidentally discovered that the hollow trigger and hammer pivot pins are only held into the chassis by the hammer and trigger spring pressure.  Rotating the hammer and triggers caused the hammer pivot to work its way out of one side of the chassis slightly.  I was able to reinstall it with no trouble and no damage was done, but please learn from my experience and do not play with the trigger assembly without it being in a receiver, or at minimum a trigger jig.

The installation instructions do not ship with the trigger as most experienced builders will not need them, however they are available for download from JMT’s website for those who want them.  The installation is not significantly different from the installation of any other drop in trigger, and as a builder, is far easier than the install of a standard mil-spec trigger, with which some folks have particular difficulty installing.  I installed the new JMT Sabre trigger into two different polymer lowers.  One was my wife’s pink rifle that I previously mentioned, and the other was an older JMT (gen 1) lower that I completed a couple years ago for a product review.  (That review was originally done for The Bang Switch, which is no longer live, but the article can be found on the internet archive here.)

Being that both of my installs were in 80% receivers that I machined (not so perfectly as I later found), neither install was as simple as it would be in a commercially completed lower.  Before starting, I knew that on the pink rifle I would need to work on the trigger and hammer pin hole alignment.  Since I was using anti rotation pins and the trigger chassis resolves any alignment issues, it was a rather simple matter that only took a few minutes to fix, but since I knew ahead of time it would not be a normal install, I did not film it.  I instead decided to film the installation process on my JMT lower, only to find during the installation that I had failed to fully machine the trigger pocket in that lower.  I had left a small lip in the lowest part of the trigger pocket that did not interfere with a standard trigger or hammer, but would not allow the Sabre trigger chassis to drop all the way in.  It was not a difficult issue for me to fix seeing as I still had the machining jig and my milling machine, but it was somewhat time consuming.  Once the machining errors were resolved, the installation was a breeze.  Again, just to reiterate, the issues I encountered during installation were issues that I caused due to errors on my part when I initially machined these receivers.  These were NOT problems with the JMT Sabre trigger. 


Once installed, I function tested both guns and the triggers functioned flawlessly, as should be expected.  The trigger pull was short and light, with a clean break and minimal over travel.  Reset was very short and crisp with almost no take up after reset.  The face of the trigger is smoother and slightly rounded, similar to the feel of a standard mil-spec trigger.  Using my Lyman digital trigger pull gauge, the trigger installed in the JMT lower averaged 3lb 12.7oz while the trigger in the ultra-manly pink Hello Kitty rifle averaged 4lb 0.6oz, which is just barely over the max weight in the advertised pull range (only a temporary issue).

Range Time
Playing with the triggers in the shop and dry firing can give you a good idea of how a trigger is going to perform, but it is not that same as actually firing the gun.  The weather, which had been quite wet for a week or so, finally cleared up and the range dried out so I took both rifles out to get some real trigger time with the new JMT Sabre triggers.  Both of the rifles that I installed the JMT Sabre triggers in are in CA legal “featureless” configuration and as such, they lack a standard pistol grip.  The pink one has an Exile Machine Hammerhead grip and the other has a Thordsen Customs FRS-15 stock, both of which are significantly different in feel than a standard pistol grip, and I have limited trigger time with either gun since converting them.  With all that said, it was not difficult to really get the trigger running quickly while keeping the rifles on target.


The triggers remained consistent throughout the testing.  The short, crisp pull was very predictable and was consistent from one shot to the next.  As previously mentioned the reset is short and pronounced which makes it easy to get the gun running quickly.  Sadly, the battery in the EOTech on the pink rifle had died and I did not have a spare, so I was having to use the backup irons which hampered my rapid firing slightly, but I was still able to get the gun running fairly quickly.

During the entire testing, I experienced only one malfunction.  It was with the pink rifle, and it was a failure to feed.  The malfunction occurred with the last round out of a 20 year old steel mag that has spent most of its life fully loaded sitting in my safe.  Also, the gun has seen probably around a thousand rounds through it since the last time I cleaned it.  I cannot remotely fault the trigger for the single malfunction I experienced.

After the time on the range, I sat back down with both guns and my Lyman trigger pull gauge to see if there was any difference.  The trigger in the JMT lower now averaged 3lb 9.8oz and the trigger in the pink rifle was now coming in at 3lb 11.3oz.  Both triggers lightened up ever so slightly, which is to be expected as they break in, and both ended up right smack in the advertised pull weight range.


The James Madison Tactical Sabre drop in trigger appears to be a solid contender in the drop in trigger market.  Construction appears to be top notch, installation is a breeze, trigger feel is great, pull is short, reset is short and crisp, it functions reliably and predictably.  I have used several of the other available drop in triggers, as well as some of the triggers from the better known manufacturers out there, and each product has its plusses and minuses.  For a solidly built commercial receiver, it is hard to beat a Geissele trigger, but for any rifle in which the trigger pin alignment might not be 100% accurate, or for a person who is looking for super simple installation, a drop in trigger pack is the way to go, and in that category the JMT Sabre is a solid product.  The kicker with the JMT Sabre is that it lists for a paltry $99.95, which is a large chunk of change LESS than any of the other drop ins on the market.  Based on my experience with the JMT Sabre trigger, I have no qualms about recommending them.