Rogue Actual put out a call on a group we are both in asking for volunteers to do a review for an aftermarket component for a Glock. I applied (and sent in my bribe and bikini photo proofs) and was awarded the chance to review the MARS (Magazine Advanced Release System) built for Rainer Arms by Battleline Industries. Cute acronym aside, the MARS is an ambidextrous magazine release for all Gen 1 to Gen 3 Glocks in calibers 9mm, 40 S&W, and .357 SIG.
I spent some time over the course of two months with it, on both my competition and duty Glock 17s. I ran somewhere north of 500 live rounds, and 3500 action cycles (during dry fire), which translated into a metric ton of magazine changes.
It is a one piece "drop in" replacement for a stock magazine replacement button.
Installation was super easy. If you are not familiar with the process of replacing a magazine release on a Glock, YouTube it (or visit your local Tier One Armorer.) You need a small screwdriver and like twelve seconds of time. I popped out my existing magazine release and slid the new one in.
Construction of the component is top notch. Battleline did an excellent job with the design and assembly. That said, I did have a slight issue with mine initially (that resolved over the course of a couple hundred magazine change drills). The catch that holds the magazine (basically a small tab) was just a slight bit longer than the tab on a OEM release (or even a Ghost). The effect is that magazines were not dropping free. All this meant is that I had to make sure I gave the release button a little more love, until it wore down a bit. It also seemed to happen more frequently on OEM Glock Magazines, opposed to Magpul (the reason I'm sure is because the OEM magazines have a deeper indentation for the catch.
So, usage... I have to say, after spending countless time drilling with my Glock, I had a hard time remembering that I had it on there. Even when I practice support hand only, it took me conscious effort to engage it.
The button in the standard location is awesome. It is large and unmistakable. The secondary button is nice and subdued so it doesn't interfere with trigger manipulation, nor with hand placement (if you have put in some time and have trained muscle memory ;).
When I was taught the skills of tactical reloading (of which I am not really a fan) and retention reloads, it involves bringing the pistol back in close, rotating the left side toward me and barrel to 11 o'clock, at which point the magazine is released and replaced with a fresh one (or whatever). At that point, I am no longer in a firing position, and can easily manipulate the magazine release. The MARS works well, here, allowing me to use my index finger, which is actually a little ergonomically superior.
When I am performing a speed reload (or emergency reload), I keep the gun out and forward. In this position, the MARS secondary button is in a poor place to operate, but the standard button is still available. My index finger just doesn't bend in such a way to give me proper leverage to engage the release. If I want to use the MARS I have to break my grip ever so slightly.
When shooting one-handed, support hand only, the MARS provided me no advantage. My thumb is just not long enough to hit the release unless I break my grip significantly.
All of that said, I still think that it is a decent upgrade for your weapon. You just need to set your expectations appropriately and spend some time training with it. The way my hand is shaped and works is not necessarily the same as yours. It is not some magical device that is going to give you instant ambidextrous utility. For me, during the more "planned" reloads, it is slightly superior. During emergency, or non-optimal reloads it was not (though it was not a hinderance; you still have the standard).
One important thing to note is that it is designed for a primary right hand operation, just like a standard magazine release. This is not going to be a super benefit if you are a south paw. And I had my buddy that IS a lefty run it a few times. He was in the same boat as me with a shorter thumb, and years of training to operate the standard release.
I like versatility. I like having options on my tools that allow me to operate them in a multitude of ways without altering the base usage. The MARS accomplishes that. At the very least, it is an upgrade to the standard release button, which was really nice. Beyond that it gives you the option of using your index finger in certain orientations (likely more, depending on your specific anatomy).
The biggest downside is just the ergonomics, and their utility throughout the entire range of magazine manipulations--but this is not an issue with the MARS. I don't know that there is any way to make an ambidextrous safety that is not going to suffer from poor ergonomics on the right side release.
Currently you can pick one up for a little over $65 at Rainier Arms at: https://www.rainierarms.com/rainier-arms-mars-magazine-advanced-release-system-for-glock