M*CARBO Brotherhood

First Impressions Of The SUB2000!

My first impressions when I shot the Sub 2000:

Don’t get me wrong but I really like this gem of a rifle. My first time shooting before making upgrades was to learn about its stock setup.

  1. Bang! My shoulder received a strong recoil. Not horrible but more than I expected. I want recoil reduction at the butt stock. and any other improvements to reduce recoil.

  2. I could not easily sight the gun with my cheek on the buffer tube at the indoor gun range (lower light). In fact with my ageing sight I could not immediately determine the front sight. I was frequently seeing the Vee as the sight. The sight itself is not painted so I was unable to determine. Something is needed in the front sight to see much more contrast. I prefer a night sight of some sort.

  3. The rear sight has too small of a whole in my opinion. The sighting system needs to be raised to get the cheek off of the buffer tube.

  4. A lighter trigger pull would be very helpful. One that breaks clean with a short return setup.

  5. An optic mounting system that folds away. That allows co witness with an improved night sight system for rear and front sights

  6. To acquire a sight vision my head is placed so low on the buffer tube that my ear protection was in the way at every shot. This is very cumbersome and not safe. A cheek lift in conjunction with raised sights is needed to correct this problem.

The rifle is accurate. I was very pleased with that aspect. I want to get on to target much more quickly. This list is in regard to the speed of acquiring a target.

My question since I understand that most of these issues have been addressed with McCarbo upgrades is: How well does the new peep hole sight address raising my head from the buffer tube? What type of cheek lift is available?

What are the other options for front sights in conjunction with new McCarbo peep hole sight?

Thanks! It would be interesting to hear of your first experience with the rifle. What did you immediately think it needed. And now that you made your upgrades just how significant did those improvements help in your enjoyment of the Sub2000?

Thanks for the input!


@TCTOPPS, Pretty much agree with all your conclusions on the S2K.
1.[quote=“TCTOPPS, post:1, topic:4871”]
Bang! My shoulder received a strong recoil.
Although recoil isn’t a big deal for me, I did add the recoil lifesaver to my first S2K. It did cushion recoil a little. My second S2K is the M series and has the recoil lifesaver, recoiless charging handle, and muzzle break. Recoil is almost none existent now.

2 & 3. The stock sights suck! They are too low and like you say, hard to get fast sight aquisition, especially with aging eyes. My first S2K I upgraded the rear sight with the MCARBO notch sight. It’s a little taller and very quick to get on target. Problem is, you’ll also need a taller front sight post. I compromised and have my sights set so that I’m on target when my sight post is only half way up in the rear notch. I really like it this way as I have a better view of more of my target…
My M Series was ordered with the peep sight. I have found that I shoot and aquire the target faster and more accurately with the notch sight. I like the MCARBO notch better than their peep sight. It is taller and faster IN MY OPINION. I’m sure there are those that like the peep better. There are lots of taller front posts available, you just have to decide what serves your needs best.
4. The trigger. The trigger on the stock S2K was horrible, and that’s being nice. Seeking a better trigger is how I discovered MCARBO. I did the full trigger job on mine including trigger bar, trigger guard and SS feed ramp, everything MCARBO offers. That is the best money I’ve spent on my S2K. trying to describe the positive difference would do it injustice. You have to feel the difference to believe it.
5. Optic mounting system. A lot of us are waiting on the MCARBO flip mount to be released. It looks to be a solid well made mount. I recently purchased a Holosun green dot optic. I really like it, very fast aquiring the target and with the taller mount, I get a lower 1/3 cowitness with my iron sights. As it stands now, I install and remove the sight so that I can still store the S2K folded and the sight does repeat when reinstalling. I will probably continue to do this on my everyday carry S2K. I would leave it mounted if it would fold a full 180*. Just folding to the side, 90*, makes it to bulky to carry in my backpack. I may add the MCARBO mount to my M Series S2K since it’s not the one used for everyday carry and compactness isn’t a primary concern. MCARBO, if you’re listening, make your flip mount fold completely under (180*). If you do this I’ll buy the first two you manufacture.
6. [quote=“TCTOPPS, post:1, topic:4871”]
To acquire a sight vision my head is placed so low on the buffer tube that my ear protection was in the way at every shot.
The taller optic mount on my Holosun solved this problem. Before that I had the same problem. Got to the point I was using earplugs instead of muffs when shooting the S2K. I’m not a big fan of earplugs though because it’s much harder to hear range commands than when using electronic muffs. Like I said, the taller optic mount solved this problem.
The gun is amazingly accurate, especially considering the bullet it’s launching is about as aerodynamic as a 1960’s era VW. Everytime I shoot one of mine I push the envelope out a little further. With the upgrades, especially the trigger and sights the S2K has become a very enjoyable firearm to shoot.


Thanks for the great feedback!


Is your Holosun attached to a QD mount? If so, which one?


No, not yet. It attaches to the pic rail and uses one torx screw to tighten the mount to it. Once I find a quick detach mount of the same height, I’ll switch to it. One thing I did have to do was file two sections of the pic rail flat on top to get the sight to repeat. Because the rail on the S2K has a slight crown on it, the sight wouldn’t mount properly until I did.


What height & length QR mount do you need?


Another vote for the Holosun. I have the 510C Elite green dot version and it’s awesome. The QD mount comes with it and it’s integrated. It works very well.


Sorry it’s taken me so long to get back to you, been one of them weeks. In metric terms, the base is 50.25mm long and 35mm tall (tallest distance, actual mounting height translates to about 30 mm from base of scope to center of mounting V). It has a 4 screw pattern to hold on the scope that is 35mm long x 10mm wide.
In good old American measurements,
1.9785 long, 1.378 tall, mounting height 1.181
Screw pattern, 1.378 long, 0.394 wide.
Looking in the Holosun manual, it states the height is 1.63" from centerline of the rail V to scope centerline. It also calls it a QD mount, but I don’t consider it to be. It only takes 1 #10 torx screw to mount but I consider a QD mount to be the cam lever type, no tools needed.

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Did any of y’all notice the shock it sends through your cheek also in stock configuration. I had to push down so hard to get a good sight picture that the recoil would jar my cheek very uncomfortable. Will soon be ordering the full mcarbo package to upgrade.


I think I have an answer for you, I will take pictures & measurements. If you live around Elgin ,IL we are having a Brotherhood shoot on the 15th.here is the notice.
April 15th about 4:00 pm till 8.pm there will be a second Brotherhood shoot at Fox Valley Shooting Range
780 S McLean Blvd, Elgin, IL cost old folks $11 second shooter $5 or $10 per lane. We also have use of a meeting room for some tall tales.Email interest, questions & phone number to last-mission@juno.com OR call 773-462-4701 & leave a message.
No names or contacts will be published.

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Sorry I could not send any pictures I’m been quite busy. Send me the sight name & number so I can tel you what QD to get. I also need what height you want to add to the sight there are different heights.Send your needs to last-mission@juno.com that will save some time. I use a pistol scope with a QD mount with high mount rings. This way I can use the iron sights or the scope at the same time. when you put the sight on the rifle it has to go on in the same spot. One Brother sugested about taking the crown off of the rail, this way the sight won’t rock. I will tell you how to do it if you want.

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