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MEAN Arms bearing delay upper

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Just wanted to post my experience with the MEAN Arms bearing delay upper now that I've had it a few weeks. I don't reload so all ammo I've shot is factory Fiocchi 115gr @ 1200 FPS.


Placed my order for the 14.5" barrel on 11/6/23. Received the upper 11/22/23.

Comes with the completely assembled upper receiver with the "K" lifter installed

2 ejectorless endomag inserts for PMAG's Gen 2/3.

"H" lifter

Instruction manual



Complete 14.5" upper assembly weight



Barrel extension with bearing pockets



BCG has not gas key, so the BCG rides on steel rails to prevent the BCG from rotating



Complete BCG weight



Bearings in locked position



Bearings in unlocked position



Spring loaded ejector on bolt face



Available lifters



Lifter selection chart



Lifter grooves for bearing



BCG with optional lifters



Configured weight minus mag with Gen 1 UBR



Configured weight with Gen 2 UBR




Got out to range to test out my 14.5” upper with the K lifter installed. AR-15 Lower has a Tubbs AR-15 flatwire spring and carbine buffer. Shot 120 round of Fiocchi 115 gr/1200 FPS and 23 rounds of Blazer Brass 147 gr/950 FPS according to the manufacturer.

They all shot flawlessly with strong ejection and locked back on an empty mag everytime.
The 115 gr shot softer with less muzzle jump than the 147 gr. It was pretty noticeable which was why I didnt bother to shoot anymore 147 gr. Definitely want to try the M and P lifter since the chart in the manual has the 115gr/1200 FPS at that intersection.

I love the polymer handguard. It appears to be a glass filled nylon and very closely matches the Gen 1 Magpul UBR, which is highly regarded and being an extremely robust stock. There is no flex to the handguard at all and feels great in the hands. Outside temp was in the low 20°, and it was a pleasure to hold them with my bare hands.



Another 200 rounds through it this weekend. This time with a Aero Precision EPC9 Glock mag lower. It functioned perfectly with zero upper related issues. I was able to cause a misfeed if i rested the Glock mag on the bench and leaned forward, it changed the angle enough to cause a misfeed and was repeatable everytime. I did not run into any issues with using the mag as a monopod with the endomags.

Also, skip the ETS Glock mags. The EPC9 lower does not have LRBHO. I destroyed one my first time on the last shot when the mag went dry. The mag/follower sits at a different position so the bolt was able to pick up the follower and shove it into the breech. When I stripped the mag out of the lower, the follower came out of the mag body. Half of the follower was still in the breech and did not allow the bolt to return to battery. The bolt goes over the top of the OEM Glock mag follower.

Follower visibly out of the mag body and into the breech.




Shot about 200 rounds through mine at a USPSA match this weekend. Total round count is a little over 500.
Ran like a champ with zero malfunctions.
Fiocchi 115gr
K lifter
Armaspec SRS Gen 4/Carbine buffer with a cutdown recoil spring. The stock spring was oversprung for me, it took about #20 to compress (my Tubbs flatwire took about #14.5). I trimmed the spring till it took about the same force to compress.


Ejector pressure after about 500 rounds. I didn't measure it out of the box. Another user measured his around 7 lbs 9 ozs out of the bow with the Wheeler gauge. He had ejection issues around the 300 round mark and his ejector pressure was in the 4 lbs range, turns out his ejector spring was broken.




Got my M and P lifters in yesterday. Went to the range to test it out.

Had a very interesting issue as my gun was getting so many light strikes almost every other shot regardless of what lifter was installed. So it was basically impossible to test out the recoil impulse since it was basically a single shot when it did fire. I noticed that it was very hard to extract a round when there was a light strike. When cycling the BCG with no ammo, there was a noticeable resistance and click before it went into battery. My original thought was the Armaspec SRS wasn’t going into full battery because i had trimmed the spring to lighten it up. I let my friend shoot it some and verified that on every light strike, the hammer strike would visibly push the BCG into battery. Spiltting the upper and cocking the hammer to fire it would work. At least this verifies that it will not fire OOB.

I took the BCG out when I got home to check the lifter/bearing interaction. When pushing the lifter into the bolt, I noticed that one ball was sticking and took some effort to push the lifter in regardless of which lifter I tried. It turned out to be the opening of small circlip that retains the ball bearing was lined up with one of the bearings, so when it unlocked, it pushed the bearing in further and wedged itself in that gap. I took a scribe and pushed the circlip so the opening was not lined up with the bearing. This fixed the sticky bearing issue and all lifters were able to smoothly push the bearing outwards.

I’m going to switch back to the Tubbs/carbine buffer in the mean time. The Armaspec has very minimal preload on the bolt due to the 2 spring system. At full extension, the secondary spring is providing the preload on the BCG. It takes about #4.5 pounds of pressure for the BCG to start moving backwards. It was probably enough preload to push the BCG into battery when it was clean (I hadn’t cleaned it until after todays session). I’d have to get some spacers to add some preload. The Tubbs spring takes around #9.5 pounds before it starts moving.

So all in all, I learned some stuff about the BCG but nothing about how the lifters felt seeing as it was basically a single shot all day. The good news is that my ejector spring is still strong and has zero ejection issues with 650 rounds through it now.



Shot around another 150 rounds yesterday evening. This time with the Tubbs/Carbine buffer and “P” lifter setup with Fiocchi 115 gr. Gun operated flawlessly and felt really good, this will be my preferred setup. Didn’t get a chance to swap lifter and compare them back to back. My buddies were impressed with how consistent the ejection pattern was. Over 800 rounds in without a single ejection issue to report.



Shot a little over 90 rounds today at a local mini match.

I short stroked it as well. This thing is flat. Like equally as flat if not more than the MPX PCC 16”, which is also a heavier gun I believe.

Zero issues once again. Solid ejection.

I let a M class/PCC USAF Shooting Team member try it out and was very impressed with how flat it was. He currently shoots a JP GMR-15 and had a MPX with all the go fast parts available. He said the JP-5 wasn’t wasnt a huge difference compared to his tuned GMR-15, but this MEAN Arms gun was super flat and he’s already looking at selling some stuff to pick up an upper. His words, not mine, also his ammo would not cycle my upper with the "P" lifter installed. We didn't have time switch lifters either. I've never shot a JP-5 or his GMR-15 so I cant comment.


The best slow mo video I have focusing on the gun



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Great information on the Mean's upper,

A few questions if you don't mind.

Are you using the Mean's with a dedicated 9 lower with the ejector removed?

Do you know if the handguard can be changed out with a normal aluminum one?

Do you think a normal AR barrel nut can be used to replace the handguard?

What trigger are you using in the lower?

How much do the lifters cost?


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6 hours ago, dmshozer1 said:

Great information on the Mean's upper,

A few questions if you don't mind.

Are you using the Mean's with a dedicated 9 lower with the ejector removed?

I’m using an Aero Precision EPC9 with the ejector removed. I had zero issues with the endomags in the 5.56 lower. The benefit of going to a dedicated Glock lower is you can short stroke it since the mag is set forward. Cant really short stroke the endomags because it sits at the back.

Do you know if the handguard can be changed out with a normal aluminum one?

Yep, handguard can be replaced. This barrel nut is proprietary to this handguard so that would need to be swapped as well.

Do you think a normal AR barrel nut can be used to replace the handguard?

Yep, you can use a standard AR barrel nut

What trigger are you using in the lower?

Hiperfire Eclipse

How much do the lifters cost?

$45 each



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Posted (edited)
21 hours ago, Texaspaul said:

has anyone else broken an ejector spring?




Shot another 120 rounds yesterday to test out some new buffer configurations.


First configuration:
Short stroked Armaspec SRS Carbine buffer with nylon spacer from Home Depot and an additional spacer for the secondary spring to increase preload on the BCG. I did not encounter any light strikes with it this time. I’d have to say this reduced muzzle movement like 10% compared to the short stroked Tubbs AR flatwire/carbine buffer setup.


Second configuration:
Short stroked Tubbs AR spring and Kynshot 5000HP. My friend had one that he was not going to use so I asked if I could try it out before he returned it. My oh my. I thought my gun was flat before but this combo was even flatter. I did 6 shots of doubles at 15 yards and could cover the entire 12 rounds group with just 3 pasters. I was almost stacking bullets on bullets with the doubles


BCG stroke bottomed out. Buffer is not bottomed out. r9UTbva.jpeg

BCG and Kynshot buffer fully bottomed out


Shot a 2 gun match today. Over 1000 rounds now with no ejection issue.


I did have a load that must’ve had a half charge because it did not cycle the BCG enough to pick up another round and sounded weak as well. RO and spectators noted that it sounded funny on that malfunction as well. 

Edited by tt350z
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3 hours ago, Bdh821 said:

Looks like it would be ejecting brass into my face if i shot it LOL.. aka not lefty friendly

I’d definitely slap on a 9mm brass deflector if I was a lefty.


Heck, I can get a cheap 3d printed one and slap it on for science and left handed shots.

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16 hours ago, tt350z said:

I’d definitely slap on a 9mm brass deflector if I was a lefty.


Heck, I can get a cheap 3d printed one and slap it on for science and left handed shots.

Now that you've shot a match with it ... do you think it's worth $1,500 ?  Would you buy it again?

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56 minutes ago, Tampa-XD45 said:

Now that you've shot a match with it ... do you think it's worth $1,500 ?  Would you buy it again?

I’d buy it again in a heartbeat. I enjoy this platform much more than the MPX. It’s nice to run my preferred stock (UBR) without having to buy a conversion kit for the MPX. The MPX was also beating up my Hiperfire Eclipse hammer, as I can see circular marks the edges were starting to shows signs of mushrooming. Also nice to be able to tune the buffer system to your preference with any standard AR parts and not 9mm specific parts.


$1,500 is pricey for an upper, but I feel the performance is worth it. I’m assuming most people already have a running AR, this worked perfect slapped onto a standard AR lower with no need to change anything. The only limitation is that you cant hold more than 30 rounds until they start delivering their 40 round mags and that you cant short stroke it, which is why I eventually got a dedicated glock mag lower.


Someone asked about spare parts and this was MEAN’s reply:


The uppers include the MEAN Lifetime Warranty, which means that we'll always fix or replace the product.  All maintenance for the Bearing Delay upper is free (including parts and labor) if the customer ships the upper to us.  For customers who want to perform their own maintenance, the first PM Kit is shipped free for any Bearing Delay upper, at the customer's request.

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  • 2 weeks later...

I’ve seen this in a match as well and the guy liked it.


My opinion, anyone saying jp5 isn’t worth it over a gmr just doesn’t want to buy a jp5. It’s a massive difference when you are at the top of your game. Even if you aren’t top of the stack it’s a huge difference. I wanted to say the same as the guy you spoke to because I also didn’t want a $3300 pcc to make sense lol. Now I’m buying a second to have as back up and keep pristine because it’s that good. 

The question above about charging the handle was because blow backs converted suffer one flaw which is the bolt is locked up and the handle is hard as hell to charge. From your pics it seems the bolt and carrier are similar to have a jp5/mp5 work which is why you don’t feel any resistance. The charge handle pulls on the carrier and unlocks the bearings. Converted blow backs can’t do this and you have to fight the lock up which sucks.

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  • 2 months later...

Finally got to try out a CMMG radial delayed gun today. One of the guy I shoot with had a Banshee that basically wouldnt eject. I told him I’d take a look at it and found that his ejector only had like #3 of pressure. I pulled the ejector spring out and it was considerably shorter than a new spring. He said he only had like 300 rounds through that spring since he replaced the original spring for ejection issues.


The MEAN Arms blows the CMMG out of the water in all shooting attributes. It is way softer, flatter, and way more consistent ejection. The only thing the CMMG has the MEAN Arms best is cost, but I am so glad that I spent the extra money on the MEAN Arms.


I haven’t added any new update simply because this thing has been running perfectly with zero malfunctions or quirks. It’s been used for matches twice a month and has not been cleaned since I switched to the optional lifter back in December 2023.

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