When initially introduced, MEAN Arms made only one insert for the CMMG RDB and straight blowback variants.
If you ordered the CMMG RDB version, they would chop off the ejector on the mag and then sand off the front of the mag as pictured below.
However some people were having some reliability issues and MEAN Arms came out with a ‘2nd gen’ version for the CMMG RDB. Picture below illustrates this. 1st Gen on the left and 2nd Gen on the right. Note that the 2nd gen has like ‘wings’ that go over the feed ramp area which prevent the rounds from jumping over the chamber.
Picture below shows the capacity limiter hasn’t been cut yet on the left and on the right, I cut it a little higher than the notch as I think it was hitting the floorplate and you can see that where I cut it is now above the bottom of the follower. Also circled in red is where I painted it for a windowed PMAG.
Rear view of where I cut the limiter above their notch.
Update 7/11/2024
There was a 4th of July sale going on and I did a search for possible mag loader options for the Endomags and Exomags since I have some friends that wanted another option instead of bump loading especially if you are somewhere where doing that isn’t ideal. I have always liked the LULA loaders but the 556 ones do not work for the Endomags as they don’t push the rounds deep enough and the ‘cam’ gets chewed up by the case mouth. I noticed that they make a LULA loader for AR15/M16 7.62×39 mags and thought I’d give it a try and it works! It works perfectly for the Endomags. The ‘cam’ doesn’t hit the case mouth with the Endomags but it does slightly touch the case mouth with the Exomags but not sure if it may just wear in or what – UPDATE: The cam definitely gets chewed up really bad with the Exomags I wouldn’t use this loader for Exomags. I’m also still kind of skeptical on the reliability of the Exomags though as they have been hit or miss for me so far.
Here is a link to the loader: https://www.maglula.com/product/ar15-7-62×39-lula-loader-unloader/
Mfr Part number is LU11B
Exomag testing
I ordered a 10 pack of the 40 round MEAN Exomags when they were available for Pre-order around Thanksigiving of 2023. My order was delivered in late June 2024. All the ones I ordered are the ‘ejectorless’ version for use with my hybrid Dissent full auto configuration documented here: https://c3junkie.com/?page_id=1733. After having bad experiences with other mags, I only opened two of the mags and fully loaded them to the full 40 rounds and then tried to strip off the first 10 or so rounds by hand. I was disappointed to see the next round just sit there before advancing up. I was skeptical they would run at all. I left the two mags fully loaded for a week before I had time to go test them. To my surprise, the two mags ran 100%. That was full auto and suppressed. LRBHO worked every time as well. Based on that experience, I opened up 6 more mags and fully loaded them as well. I also did the same thing and stripped rounds off them by hand and seeing the same behavior of rounds not advancing. I left them loaded for at least a week as well. I had a SMG match coming up and got a chance to run all 8 mags the day before the match. This time it was hit or miss including the first two mags (I used a silver Sharpie to number all my mags to keep track of them). It was so bad, I didn’t want to use them in the match the next day. I left them all loaded again. I ran them again a week later (7/20/24) and they seem to be working now but I am still leary of them. I may try to run them at the next SMG match.
Update 7/28/24
I ran 4 of them that were fully loaded for a few weeks in full auto with some flat nose 147Gr which BTW these Exomags feed them very well (it feeds everything very well when it behaves). This time it ran all them 100%. So I plan on trying them at the next SMG match.
Update 8/4/24
We had a short SMG match due to inclement weather but the 40 round Exomags that I did run all did so 100% with my 147Gr flat nose bullets I ran. I had left all the mags fully loaded as discussed previously.
Update 8/31/24
I ran several of the mags again and had several occurrences of having the bolt go forward on an empty chamber. I suspect the rounds are pausing in the mag again. Pretty sure not a gun problem as there is no jam. Switching to the Endomags and it runs fine. I have been leaving the mags loaded as well.