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If you shoot in 3-gun competitions or are just 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 Extensions by Coronado Arms. [Noobs note: a magazine base plate is the piece on the bottom of the magazine that holds the follower, magazine spring, and whatever other goodies your magazine may have inside. A mag base extension is an upgraded version of that plate that “extends” the functionality of the off-the-shelf plate, adding to a magazine’s round capacity. They can also add a personalized (and colorful) touch.] The bases from Coronado are available in . . .



blue, gold, green, purple, red. If you want something a little more subtle, they also offer them in basic black. Coronado’s extensions are bolt-on accessories that will change the look and feel of your rifle, and magazines quickly and without hassle.




Functionality & Features

One of the primary functions of an extension is to add round capacity to magazines. One of the best ways for shooters to cut time during matches is to limit or avoid reloads. The Coronado Arms PMag Extension adds five additional rounds to your standard PMag, so your standard 30-round magazine just became a 35-rounders. You use the factory magazine spring so the spring is a little “stretched” in these applications. That 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 (about 2.6 oz.) to the magazine base. The extra heft can help the magazine fall from the rifle with a little more authority. It may not be a big deal for normal usage, but during competition in which shooters are trying to cut fractions of seconds from re-loads, every little bit helps. For high-speed re-loaders, ensuring the magazine falls reliably and quickly is critical.

Depending on conditions where you shoot, your mag extensions will get a little dinged up, but they’re tough enough to take it.



Also, when carrying extras, the base provides a very positive “handle” to grab on to when reaching for a fresh mag. So you shouldn’t have your hand slip off of the magazine if something gets tied up in your gear a bit. That’s never a bad thing.



Coronado Arms also offers a dual extension (above) that allows you to connect two magazines together and attach the same way as single bases. 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 slam the full mage right back into place. While two full mags hanging from your rifle adds a fair amount of extra weight, it’s 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’s obviously wider than a single magazine and can get in the way if you aren’t used to it.


The Coronado Arms PMag Bases fit on 20-, 30- and 40-round Gen2 and 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 and off. You could probably shave some material off of the mag and make it work, but if you’re running 10-round magazines, there’s a good chance extending the capacity isn’t legal where you are to begin with.

The extensions fit very tightly so there’s no rattle, wiggle or other movement when installed. You can grab and tug on them and they will stay nice and secure.




Installation of the base extension is pretty simple. First, remove the existing base plate by pressing in the grey bar on the bottom of the magazine and slide the stock plate backwards off the magazine. Make sure to catch the spring, or it will launch across the room. You will need those parts.

Once you have the Magpul base plate off and the magazine disassembled, remove the gray plastic plate attached to the bottom of the magazine spring. When that is removed, you are ready to put the magazine back together with the new base plate extension.

First, 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: * * * *
At $30 MSRP, the Coronado Arms base extensions are priced well and in most cases lower than many competitors.

Ease of Installation: * * * ½
Installation of the base plate is easy, though it does require tools. Sometimes this can be PITA on the range.

Durability: * * *
The extension seems to be pretty durable. I haven’t driven over it with a truck, but you probably shouldn’t do that to your magazine anyways. They’ll develop superficial scars pretty quickly, but none of that will affect functionality.

Usefulness: * * * * *
It does all the things you would want from a mag extension. Increased capacity, good look and feel, etc….

Overall: * * * *
They work well, look nicely and are easy to install and maintain. Definitely worth your consideration.

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  1. Okay using the dual connector job to put two 40-rounders together (so 90 total) would be a ton of fun! But I’m not sure I can afford the ensuing mag dumps haha

      • I’d much prefer the jungle-style dual 45-round PMAGs over the notoriously unreliable Beta C-Mag 100-round drum magazine. I’m not aware of any reliable STANAG magazines of 90 or more rounds.

        • Nick Leghorn reported his Surefire MAG5 100-round magazine was reliable in his TTAG review. I haven’t read too much about the magazines so I don’t know if it’s the consensus in the community that the mags are reliable, at least with 5.56mm/.223 ammo. I should probably look into that, I generally only trust Magpul (when properly stored unloaded or with the dust cover to protect the feed lips) and Lancer (whose steel feed lips don’t deform when left loaded) when reliability is of utmost importance, when in defense of life, but if the MAG5 is truly reliable I think I ought to pick up a 100-round magazine for home defense and forget about magazine changes.

  2. Why not just buy two extra magazines instead of paying $30 for one base pad? There are few things as reliable as a PMag. Leave well enough alone.

  3. So doesn’t adding more length to the magazine negate all of the the R&D and testing that Magpul did on their magazines to determine the ideal spring characteristics? Uhhhhh….that doesn’t sound too smart.

    Of coarse maybe Josh did as much testing as the Magpul corporation.

    • I always seem to be the guy reminding people that it isn’t always life and death when talking firearms. They also exist for hobby and fun. Adding 5 rounds of capacity and marking certain magazines with different color baseplates (designating caliber e.g. red for 5.56 and blue for .300 BLK or type of round within a caliber, e.g. 55 grn vs 77 grn vs whatever) can be really handy for recreational use and for things like gun games, as mentioned by Josh. Adding 5 rounds to your 3-gun competition mags can be a big benefit. Or you can go punch paper in the woods and do it just for fun and color. Why not? Even if the possibility exists that it isn’t as durable and reliable as the OEM, untouched PMAGs it ultimately just doesn’t matter for recreational purposes, and that’s a perfectly acceptable use for a firearm!

      RE Rand above your comment, when you’re on the clock in a competition, swapping a mag takes time and adding 5 rounds to your existing mags can be a big help. Look at the top 3-gun competitors and you’ll see they all use magazine extensions.

      • IMHO if this article was written up as BLING! for your AR then I would have be totally cool with it. But trying to technically justify a 30$ mag extension that costs 1.7X the cost of a PMAG 40 just kinda makes the BS detector go red. OTOH, I’ll concede that there might be some ultra extreme 3-gun advantage.

        BTW, Jeremy, I love your choice of hardware. Keep doing what your doing.

      • I can’t stand thirty round mags anyway. Twenty is plenty. 3 gun competition? I am lucky to afford to shoot twice a month as it is. Why do all these gun writers assume gun owners have an unlimited budget? Get real.

  4. For me, where I multiple uppers in different calibers, adding these to just the mags I like to use for those uppers is a no brainer. “Oh 300BLK? Grab the blue aluminum mags from the safe.”

      • You can also wrap some tape or paracord around the mag, with different colors for different ammo.

        PLus with paracord and tape you can make a small extension on the mag to make it easier to pull out, similar to those Magpul magpuls.

    • Or you can save your cash for ammo and color-code your mags with a strip of electrical tape. It comes in multiple colors for, gee, color-coding different runs of romex…

  5. Both Midway and Brownells sell Pmags for $12.30 and you can get 40 rounders for less than $20. Unless you are a competition shooter and you desperately need 45 rounds to get you through a stage without reloading, I see no need to spend twice the cost of a magazine on a 5 round extension.

    • Yeah, what about the guy who has 25 or more mags. At 30 bucks a pop, that’s $750. You can but another AR for that!

  6. I like the tactical applications for these extensions. When employing kinetic, spin-enhanced extension of force dynamics into an asymmetric force encounter, utilization of the load-based mass effect of non-dynamically pseudo-stabilized ammunition carriers could add significant lateral striking force.

    See Dynamic Pie Concepts – the Art of the Mag Flip for more details.

    • Love it. As soon as I started reading your comment I started laughing because I knew exactly where it came from. That video is hilarious.

      • That is some funny $h!t right there! THAT is why I still read the comments on TTAG. Guess my 10 GB limit Intertubes connecction will be smoking tonight.

  7. With modern day CNC equipment, and multiple set up’s, these things could be churned out by the thousands. Were not talking stainless here.
    I’ll certainly agree they look like a quality item, but mass production should bring the price down to half of the now listed figure

    • I prefer to slam mags as well. I wonder why he said Mage. Maybe he has a kink for that. Of course, he could also just be typo-ing, but that’s highly doubtful. SURELY he meant Mage.

  8. Be aware, some 3 gun matches limit mag length to the equiv of a std 30 and others limit capacity to 30.

    Everywhere I shoot its a 30rd limit.

    What would be nice for me is being able to load the mags to 30 so if I have to reload on a closed bolt i don’t have to worry about the mag not seating. A lot of competitors will down load mags on the belt to 28. I saw many people on stage 7 of the fnh 3 gun match perform the mandatory reload between paper and steel and then proceed to have a ton of malfs.

    There are a ton of mag extensions out there.

  9. Oh boy! I was just thinking that I haven’t spent enough money on my AR. Now, where’s my credit card…?

    • It could be much worse. Someday, I want to have enough money (and little enough sense) to think that things like a .50 BMG SBR are reasonable.

  10. Mag limit in NJ is 15, so I can think of one example where it would be useful to add +5 to a 10. My brother in Jersey just buys 30 rounders that were permanently modified to 15

    • But THAT is the reason I don’t find as much enjoyment reading the comments. Way too many people type their rude, hateful, juvenile comments because they are anonymous. Yeah, you can be a dog on the Internet and no one knows, as we used to say. Just makes others less and less tolerant of dogs.

      I keep hoping the “people of the gun” would show more class, or at least respect to each other. My bad. Lesson learned. Again. Still.

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