Coronado Arms PMag Extension


Do you shoot 3-gun competitions or maybe you are interested in some bolt on mods for your AR-15 that can add some color and capacity to your magazines? Check out the new Magpul Gen3 PMag Base Extension by Coronado Arms.


What is a Mag Base Extension you ask?


Well, a mag base or magazine base plate is the plate on the bottom of the magazine that holds the follower, magazine spring, and whatever other goodies your magazine may have inside in place. A mag base extension is an upgraded versions of that simple plate that “extends” the functionality of the stock plate. An example of this would be added round count to the magazine; as well as adding a personalized (and often colorful) touch to magazines.

Now that we all know what a Mag Base Extension is…



Lets start out real basic… Mag bases are a quick and easy way to add some color to normally black rifle and accessories. The bases from Coronado are available in Blue, Gold, Green, Purple, Red, and if you don’t want to add some color to your rifle, they also offer them in Black. But it’s a simple, bolt on accessory that will change up the look and feel of your rifle, and magazines quickly and without hassle.


Functionality & Features

One of the primary functions of the base plate is to add round capacity to magazines. One of the best ways for shooters to cut time during matches is to not have to reload (or help limit reloads). The Coronado Arms PMag Extension adds 5 additional rounds to your standard PMag, so your 30-round magazine just became a 35-round magazine. You use the factory magazine spring, etc. so the spring is a little “stretched” in these applications, that being said I didn’t have any failure to feed (FTF) issues or instances where the bolt wouldn’t lock back. Everything worked as normal.

Another benefit of the base extension is that it adds a little weight to the magazine. When it’s all said and done, it adds about 2.6oz to the magazine (7.6oz total weight). This slight bit of added weight seems to help the magazine fall from the rifle with a little more authority. It may not be a big deal for normal usage, but in things like competitions where shooters are trying to cut fractions of seconds from re-loads (if they have to reload), every little bit helps. For high-speed re-loaders, ensuring the magazine falls reliably and quickly is of key importance.

In testing I did a couple drops of the magazine, unfortunately the range where I could do this were pretty rocky and after a couple drops the base plate got dinged up. It’s all superficial scars, everything still functions as expected, but it’s worth noting.


Also, a side perk, is that if your magazines are hooked into magazine carriers on kit, like a chest rig, the base gives a good positive area to grab on to… So you shouldn’t have your hand slip off of the magazine if something gets tied up in your gear a bit. A little more purchase power when pulling magazines from gear is never a bad thing…


Coronado Arms also offers a dual pmag extension that allows you to connect two magazines together. It works in the same fashion as the single bases, it’s basically two of them machined together. This works well for really fast mag changes as you simply have to pull the magazine down, move it over an inch or so, and then right back into place with a full magazine. This does add a fair amount of weight to the gun (2 magazines of ammunition hanging from the gun). But it is definitely a time saver and can help mitigate some recoil. Just make sure it wont interfere with how you’re planning to shoot, because it is wider than a single magazine, and can get in the way if are not used to it.



The Coronado Arms PMag Bases fit on 20, 30 and 40-round Gen3 PMags. They do not fit on Gen3 10-round magazines. The 10-round mags are designed a little different and the base will not slide on, you could probably shave some material off of the mag and make it fit if you were really hard up for it, but without some modification to the magazines, they only work on the larger capacity PMags.

The extension fits very tight on magazines, so there is no rattle, wiggle or other moving around when installed. You can grab and tug on them and they stay nice and secure.



The installation of the base extension is pretty simple, first you remove the existing base plate by pressing in the grey bar on the bottom of the magazine and slide the plate backwards off the magazine. Make sure to catch the spring, otherwise it can go flying… and you need those parts.

Once you have the Magpul base plate off and the magazine apart you will need to remove the gray plastic plate attached to the bottom of the magazine spring.

After that is removed, you are ready to put the magazine back together with the new base plate extension. First thing, put the magazine follower and spring back into the magazine, making sure they are going in the right direction. Then press the spring into the magazine while sliding the back of the magazine extension (the longer part) on to the magazine. Once that is all the way on, the magazine spring should rest in the bottom of the extension, there is a bevel cut into the extension to help keep the spring in place.

Once you have the larger base potion fully pressed on to the magazine, you can press on the front cover. It should slide into place without too much resistance, but may require a firm press to get the screw hole on the bottom to line up. Once everything is pressed together completely, install the screw in the bottom portion of the extension and tighten. You will need a 5/64 allen wrench for the screw, you can get one, here.

You may have to wiggle things around a bit and give a firm press to get everything together. The extensions are pretty tight to keep them from rattling or moving around. So with anything that is “fit”, you may have to use a little force and make sure things are lined up correctly.

Once you have everything together, you can use the magazine as normal. If you ever need to clean or remove the base plate, simply take out the screw and reverse the process. Quick and easy, and no issue with magazine spring, etc.



Weight (single) 3oz (2.6oz added to overall magazine weight)
Weight (double) 7.4oz
Length 3.012in (76.52mm)
Width (single) 1.170in (29.73mm)
Width (double) 2.952in (74.99mm)
Height 1.432in (36.37mm)
Additional Round Count 5
Supported Magazines Magpul Gen3 20, 30, 40-round magazines
Material 6061-T6 Aluminum
Anodizing Type-2
Required Tools 5/64in Allen Wrench


Ratings (out of 5 stars)

Price: * * * *
The Coronado Arms base extensions are priced well, $30 MSRP, and in most cases lower priced than many competitors. So if you are in the market, on price alone they are worth checking out.

Ease of Installation: * * * ½
The installation of the base plate is easy, though it does require tools. Sometimes this is a pain in the butt on the range. Since this is more of an install and forget about it product, it shouldn’t impact your on the range toolbox once it’s installed.

Durability: * * *
The extension seems to be pretty durable. I haven’t driven over it with a truck, but you shouldn’t need to do that with your magazine anyways. They will get superficial scars pretty quickly, but none of that effects functionality… But it is nice for shiny things to stay shiny.

Usefulness: * * * * *
As far as base extensions go, this one does all the things you would want from one. Magazine capacity, good look and feel, etc…

Overall: * * * *
Overall, these are good and well priced extensions. If you are in the market for extensions, check them out. They work well, look nice and are easy to install and maintain.

Visit the Manufacturers Website

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