M*CARBO Brotherhood

SUB2000 Upgrades: What Have You Installed & What’s Your Opinion?


It will close with the spring either way on mine. I installed the new trigger springs, cleaned everything, and it’s sealing fine. The trigger is awesome compared to what it was. Someone worked on it, or had it apart and had something off.
I have a mauser 1918 30.06, it’s trigger is 2 stage- first pull to resistance is like a safety, then real trigger begins. Absolute nightmare to sight in. That’s how the trigger felt in this to begin with. Pull almost all the way, feel a click then trigger pull. Now it’s a nice, single break. Can’t wait to shoot it. Stopping on the way to have the gun shop help me with the barrel nut. Only supposed to be hand tight but it’s been torqued.


Okay, so with the forend off, the barrel still wasn’t locking fully to the receiver. It’s hitting at 12, 3, and 9 o’clock. The barrel nut was way too tight, hoping that correcting barrel placement will fix the root of it and the aluminum guard will clean it up. One question, the flat washer between the nut and block has a side that both corners are notched, what side should they be on?


If you have it in the firing position, unfolded, both notches are on the top for mine…
There’s 2 little ears on the fore grip that fit in to the notches.


That’s what i thought. Somebody did some shoddy work. I stopped at the gun shop to see if they had a tool for the nut, which they didn’t, “at least the trigger is better.” He pulled the charger, pulled the trigger, “wait, it’s supposed to feel like a two stage or that’s what you fixed?”
So it will pull 2-3 times nice, then feel like there’s give until it bumps, then short pull to fire. Do that a couple times then good trigger.


So, 150 rounds and i think i have the barrel locked. The flat washer wouldn’t sit flush against the barrel block. To sum it up, there was too much gunk around the 1/4 inch of thread closest to wear the barrel went into the block. The bulge the washer sits over apparently was covered too, a tack- hammer and punch until i got the washer flush, then had to work the nut back and forth until it would run down.
It would feel like it was tight but once the washer was out of the way, i could see the remaining gap on the threads.


I put together a little oops kit since I couldn’t seem to find one from anybody else.
oops kit consists of the following.

  1. firing pin
  2. firing pin spring
  3. firing pin pin
  4. extractor
  5. extractor spring
  6. extractor pin
  7. mag release spring
  8. safety detent
  9. safety detent spring
  10. E Clip
  11. washer


Phil, just the sub2000 and was directed to this site by the gun store! Great products. I’m looking forward to the trigger kit myself. Thanks for the update1


If anyone cares I installed my new trigger bar on my Sub2K today. My opinion is that it works as advertised. It takes up the slack in the trigger before break and it does break more cleanly. What it doesn’t do is affect the trigger reset. The reset is still non existent. The trigger is on and off, that’s it. If you are doing the trigger kit I highly recommend you get the trigger bar with it. It’s pretty much a no brainier. I’m not so sure I’d go through the hassle of adding it if you’ve already done the trigger kit though. It may be worth it to folks who don’t mind taking their gun apart. I’m one of those people. I was watching the race and cleaning guns today so I didn’t mind the hassle. Bottom line, it makes your SUB2K better.


@msydnor Thanks for your input. About to install mine


did you do the modification to the trigger bar or did you just leave it as is?


Let it as is. I didn’t know there was a modification to it.


What modification? It just came out. What did I miss? Thanks.


look up " sub2k reset issue " on the forum and scroll up and you’ll find your answer.


here’s a link to the thread.


Highly recommend to mod it before install, a slight hiccup that @ChrisNelson has a fix for.


Got my Oops Kit from Omnivious and added it to all the stock parts I pulled in favor of Mcarbo parts and put them in a little waterproof Plano box. This box of parts goes wherever the S2K goes so field repairs can be made if needed.


Hello, I am a brand new customer and just signed into the website and forum this weekend. And, low and behold, you guys were running an amazing Labor Day sale. So, I decided to buy everything you have for the Sub-2000…accept the Performance Trigger Bar…it was out of stock so I will pick it up when it comes back in.

Just wanted to say thanks for the products you offer and your great support to the military. I look forward to getting all my new parts and getting them installed.

Happy Labor Day!



@Quick1 I think you will like the difference when you install the MCarbo parts. Thanks for your service and welcome.


welcome to the brotherhood and looking forward to hearing what you think about the new parts.


Recoil isn’t bad, but being that it’s against my jaw it’s not exactly comfortable to shoot a lot of rounds.

Because of this I ordered the buffer tube cover, recoil buffer and recoilless charging handle from M*Carbo. Will the 9mm S2K function and cycle normally if I use the MCarbo recoilless charging handle along with the Kel-Tec brass heavy weight bolt?