January 2026 – I posted about using the Omni Robusta magnetic buffer (https://www.thefirearmblog.com/blog/2020/08/17/omni-robusta-marrs-magnetic-adjustable-recoil-reduction-system/) in conjunction with the CMMG RDB system. The inventor of the Omni Robusta magnetic buffer sold his patent to Jerry Miculek. https://miculek.com/products/miculek-magnetic-buffer-system. At the time of this writing, Miculek only sells the aluminum plunger version which IME, shears apart as discussed here: https://c3junkie.com/?page_id=3168. I improved on it and while my version worked great in 9mm and 556. I tested it on a .40SW build and it sheared apart as well. Pictured below is the best I got with the system. I thought it was smoother in full auto than any of the hydraulic buffers but due to possible patent infringement issues and durability concerns I only made a few for myself.
3/2026 – I also tested the Pamax https://pamaxtactical.com/ magnetic buffer setup and it doesn’t seem to have a good way to stop carrier bounce and sure enough it was not reliable in full auto at all. I tried different spring and spring rates as well.
Both of the commercial options above use magnets repelling each other.
2/2026 – u/TeufelTechSolutions on Reddit posted that he invented the first eddy current buffer system and is pursuing a patent. https://www.reddit.com/r/AR9/comments/1qk1uqk/i_invented_the_first_eddy_current_buffer_system/ I haven’t seen any pictures on the components for anyone to copy. However, as discussed below someone from Reddit mentioned this document about using magnets and Eddy currents for damping gun recoil here: https://www.proquest.com/openview/a22f151e5419c4351e290a9d590d53c6/1?pq-origsite=gscholar&cbl=4998668 That document shows June of 2023.
8/31/2026 – u/AddictedToComedy on Reddit posts his success on using magnets with Eddy currents with the CMMG RDB system. He is a customer of mine and isn’t interested in selling these things. Just wants to ‘open source’ it. https://www.reddit.com/r/AR9/s/0hC8xKfmsB
In his configuration he is using a lightened carrier that I did the work on, he is at only 10.5oz of total reciprocating mass…but again it looks like his setup may have carrier bounce issues which would result in light primer hits in FA / FRT / SS mode.
9/1/2026 The very next day u/SnazzyShootas on Reddit posts he has already been running magnets with the CMMG RDB system leveraging Eddy currents as well for a few months. https://www.reddit.com/r/AR9/s/I0ReeZPzFf
He also advised to use a non-magnetic castle nut and end plate to avoid the magnets from being attracted to them and used Titanium ones.
Based on both of their results, I posted in the thread above about doing a configuration like this:
9/5/2026 – A5 buffer tube testing (7075 Aluminum)
I have completed some initial testing. I am using the Fortis aluminum K1 castle nut and endplate that I have listed here:https://c3junkie.com/?product=fortis-k1-lightweight-non-magnetic-castle-nut-and-end-plate Note that both guys above were using the JRC buffer tube while I have A5’s installed on two M16’s at the moment. So I figured I would test with A5 length first. I was using this one: https://c3junkie.com/?product=kak-a5-style-ar15-buffer-tube or this one: https://c3junkie.com/?product=griffin-armament-maritime-ar10-a5-equivalent-buffer-tube any A5 equivalent works which has an internal depth of 7.75″.
The ‘puck’ used in all tests below was provided to me by u/AddictedToComedy on Reddit and consists of one 7/8″x1/2″ N52 magnet in a 3D printed housing he made and also has rubber washers to cushion the magnet since they are brittle.
You can see that the Strike Industries ‘pistol’ spring is the shortest and yielded a slower cyclic rate than the Tubb LW. (578 vs 598 RPM)
I need to mention that since we are not using a traditional buffer and for best effectiveness, the spring needs to be behind the puck. Even with the Strike spring, I can feel it is considerably harder to charge than a normal setup. It gets worse adding my additional spacers and wave compression spring. After getting the baseline of the results above, I figured now is the time to cut some coils off my C3Junkie spring. https://c3junkie.com/?product=c3junkie-flat-wire-buffer-spring So bear in mind that in tests 1-5 above will all yield slower cyclic rates with shorter springs but I didn’t bother to repeat tests 1-4 with cut down springs.
What’s next???
- As mentioned above, I’m going to move back the JRC buffer tube for more spring travel and hopefully get slower to the low 600’s in cyclic rate and keep this low reciprocating mass. I am going to make a new spacer that is 3/4″ longer for use with the JRC tube.
I have also been thinking that since I have to make a spacer to prevent the carrier key from hitting the lower, I can ‘anchor’ the spacer to the bottom of the buffer tube and make it hollow to hold another magnet to attract the moving magnet to delay the cycling to slow the rate down. Or maybe just use steel to attract the moving magnet or just leave it empty if those options don’t work out. Another thing I forgot to mention is that LRBHO is sporadic. It is amazing that the magnet is so effective in slowing the BCG down. I’m hoping that making this modular ‘anchor’ in the buffer tube will allow me to further tune the action for consistent LRBHO as well as maintaining ‘constant recoil’. - All this testing was with my ported AASD so I will want to test with my favorite non-ported 8″ upper that I like to run. Based on the data from u/SnazzyShootas and u/AddictedToComedy, I anticipate needing to use the larger 25mm magnets that I have on order.
- Assuming I get to a happy place with 1 and 2, I do plan on testing this setup in one of my tuned 5.56 setups as well.
9/7/2026 – JRC buffer tube testing (tube is most likely 6061)
I mentioned that I didn’t want to cut my spring shorter that I used for Test7 in anticipation of using it with the JRC tube and I’m glad I didn’t cut it more since it felt weak in the JRC tube but actually ran fine.
At this point, I was thinking to move up to the 25mm diameter magnets for more strength to handle a non-ported barrel but figured let me try it anyways with the same lower setup and just swap to my 8″ upper without a suppressor first.
Obviously, the next test was to add a suppressor and in this example. This is my ‘Phat Girl’ which I consider an improvement to the MK9K and CT9KS which is coaxial and easier to service with push through stainlesss baffles.
Since I liked this setup the best, I loaded up some 40 round Exomags to the max to see if it could strip a round off a full mag and it did. Running bursts of full auto, I had 2 occurrences where the gun didn’t jam but I had an empty chamber with live rounds still in the mag. I then tried my 33 round CMMG mag, loaded it to the max and ran bursts and the same thing happened 1 time. I have run into this issue with Endomags and Exomags but I can’t recall it happening with the 33 round CMMG mags. I lubed the gun up some and tried it again with the same 40 round Exomag and it happened once.
I hate the look of Glock mags but they have always been the most reliable with the CMMG system for me. They position the mags the closest to the chamber than any other magazine so I am considering doing future testing with Glock mags and see if this happens again. If it doesn’t happen again, it could be the mags or possibly the magnetic buffer setup is braking so much that the bolt is going back far enough to kick the brass out but not far enough to strip off the next live round in the mag which again since Glock mags are closer to the chamber, should not happen.
Some additional points: From the post I put on Reddit: https://www.reddit.com/r/AR9/comments/1w92es9/more_magnetic_buffer_testing_with_eddy_currents/
u/Eleet007 – Apparently 6061 aluminum is a better conductor than 7075. If you start experimenting with eddy current braking yourself, it’s probably better to use a 6061 buffer tube for more of an effect. I have not seen anyone else mention this.
From a Google search,
“Electrical Conductivity
Why: The higher concentration of alloying elements like zinc and copper in 7075 disrupts the flow of electrons more than the lighter magnesium and silicon mix in 6061. [1]
6061 aluminum: Delivers about 43% IACS (International Annealed Copper Standard) electrical conductivity.
7075 aluminum: Achieves about 33% IACS electrical conductivity.”
Also from that thread:
u/wopeecushion – “Stacking backing iron disks on both sides of the magnet will focus the magnetic fields outwards toward the buffer tube.
To increase efficiency more you can use thinner magnets but more of them, interleave with iron disks and put the magnets facing each other. The stack should hold up and have a very strong alternating magnetic field going radially. This is similar to a halbach array.
To increase the magnetic eddy current efficiency even more you can add an iron sleeve on the outside of the buffer tube that will act as an outer backing iron for the magnetic field to loop through.
Google “permanent magnet recoil damper” for a nice scolarly article from some chinese scientist and many other treatises.”
That article he mentions is here – https://www.proquest.com/openview/a22f151e5419c4351e290a9d590d53c6/1?pq-origsite=gscholar&cbl=4998668
When can I get one of these setups? – I’ve had a few people ask me about this and as of this writing it has only been a few days. I typically run around 400 rounds in the monthly SMG match I go to where I run full auto and suppressed. I wouldn’t consider selling anything that isn’t reliable in these matches. So far testing has been great but I haven’t even taken this setup to a match yet as I just made only 2 range trips doing testing. I post as much detail as I can so people that have the means can try it for themselves and also hopefully share their results like I am doing.