M*CARBO Brotherhood

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


Let me know how it worked out for you, what results you ended up with …


The 40cal will leave you bruised and thinking twice, unless you have the upgrades. The 9’s that I use have no where near the recoil … I did put the buffer in all of them, the heavy charging handle and muzzle breaks and added added the Keltec heavy bolt only to the 40cals … I generally shoot bulk ammo from Georgia Arms and typically the 180gr FMJ for 40cal and the 115gr for the 9’s … cheap ammo… However I have been shooting their rounds for several years now without any problems … http://www.georgia-arms.com/ … They also will ship it to you …


@Firedog That is true, I have the S2K in .40S&W with the MCARBO recoiless charging handle, bolt buffer, muzzle brake plus the Kel-Tec heavy weight bolt and ATI butt pad. All of these items are needed to reduce the recoil on the .40 and make it more enjoyable to shoot.


i will. For an academic project if nothing else, I have been working on a whole new bench design.with a solid, lock down capable rifle rest.
Then my plan is to set up a separate video camera to run on, 1. the gun and shooter, 2.the load/ejection cycle of the action, 3.the bolt/charging handle cycle (if I can), 4. muzzle and target.
Then record as much data as possible shooting various ammo, yardages, charging handle weights, and any other variables I can try, under as controlled conditions as I can make them.
I dont have a chronometer, which would be nice, but the rest I can do.
Might be a waste of time in the end but we’ll see.


I added a green laser/light Monopod grip to the rail down below. Just point and shoot


I have been reviewing the videos. I polished the lower feed ramp Wich looks fantastic. I wasn’t unhappy with the stock trigger pull and wanted to save some money. So I went ahead and installed the lower feed ramp. Took all the innerts out just to have some experience. All went well. Before I did any of this I put 100 rounds of Remington 9 mm Luger 115 grain FMJ training ammo through it using the 17 round and 33 round magazines. No misfires. Loved it. After the install same ammo, I only could pull off no more then 4 rounds. The round feeds into the chamber but won’t engage in firing. I had to drop the magazine eject the shell that was in the chamber, cocking it and load the magazine then it would fire sometimes one round to 4 rounds. Something it wouldn’t fire at all after following that same sequence. Not Shure what to do. Got home and it chocks and trigger function works every time. I will try some different ammo and see what happens. I don’t think I should break it down again unless it’s suggested by the guys in this forum.


@Magboy Not a lover of Remington ammo but I don’t think that is your problem. Does your brass have any unusual marks or scrapes on them? If the bolt is not fully forward it will not fire. Did you remove the upper feed ramp, part #247 and maybe installed it backwards? It’s a pain, but I would put the stock plastic back in and see what happens. The Brotherhood will get you up and running.


I didn’t remove the upper feed ramp. Same cartridge’s as the first two boxes. 100 cartridge’s with no misfires. I’m wondering if the new polished lower feed ramp caused the problem. But it’s not from the feeding into the chamber, at least I don’t think so. I’d fire one shot or two or three or four rapid ones then the trigger would not fill any pressure. I’d have to drop the magazine out and eject the one in the chamber. Then cock the bolt and load the magazine it would load the cartridge in the chamber but there’d be no pressure or it would have pressure and let me fire one to four shots then nothing.



I should mention that after the first 100 rounds I attempted to clean it. Loading the bolt in it wouldn’t engage all the way in, just to the hammer. I think maybe I didn’t have the safety on when I took out the spring and bolt but not sure if I had the safety on or not. I did run a dowel rod in the reset the hammer but the bolt stopped short hitting the top of the lowered hammer. I then could put my finger in far enough to push the hammer down enough while moving the bolt over the hammer. It then was fully engaged. I was able to cock it and dry fire it over and over and using the safety on and off with no problem.



Hey what’s up guys? Just finished installing all the parts i ordered. Funny thing is I had all the parts before i even had the gun in my hand, I never got to shoot it “stock”. I installed keltec heavy bolt, mcarbo Glock extended magazine release, mcarbo bolt tube cover, mcarbo pro performance trigger bundle w/ curved trigger, mcarbo dbl finger extended charging handle, mcarbo stainless steel feed ramp, mcarbo recoil buffer, magpul afg2 grip, holosun red dot, and a temporary mount for the red dot while i wait for mcarbos model to come out along with their muzzle brake (out of stock). Can’t wait to take this thing to the range and see how it does.


All I’m missing is the trigger bar. Got an email back that they’ll restock hopefully by Oct…


Sounds like the internals may be misaligned, did you put a mag in the grip halves when you put it back together and make sure the springs were all seated well? If the grip halves are slightly out of alignment, it can cause feed issues…


Yes I did. I think I’ll try some different ammo federal first before I take it apart again.


It actually does not sound like an ammo problem. I think you’ll find that a spring snuck out of position.


I was thinking the same thing, unless you were trying to feed it some steel case or aluminum, I doubt it’s an ammo issue…


Maybe, I guess I’ll have some more experience going through it again.

Thanks for your help.



Had the same problem the first time I cleaned the gun. Wasn’t as adventurous as you to push the hammer I just kept tilting the barrel upward and finally (still not sure why) the bolt slid all the way forward and seated.


Thanks for sharing



Installed a MagPul fore rip and Crimson Trace green laser. Working very good. Awaiting my ‘kitchen-sink’ order from M-Carbo - should make this gun even greater.


@Noslen Yes, you are right…MCARBO does make the Sub greater. I have the same forgrip and it just looks and works with the Sub2K perfectly.