New guy with a new Sub 2K with question

Wifey surprised me (completely) with a Sub 2K for Christmas. Back in October, she surprised the heck out of me with a Mossberg Shockwave. Maybe she knows something about an impending zombie apocalypse? (Let’s see how this forum handles photos…)

By Christmas night, I had discovered MCarbo’s goodies and filled my cart (but haven’t yet hit the checkout button). I want to make sure my ducks are in a row, first.

Today, I got the Sub 2K out to the range for a shakedown. 130 flawless rounds fired. But I quickly discovered a couple of things. Well, first I was reminded about the condition of my 59 year old eyes! I can’t focus on the front sight. And then a black front sight on a black target… fuggedaboutit!

I managed to do this at 25 yards, despite not being able to get a good sight picture.
(OK… apparently I’m limited to one image as a new user. Bummer.)

Plus, the stock rear sight is too low, forcing an awkward cheek weld.

I need an optic on this bad boy, pronto! I’m considering the Holosun Paralow HS503G with the ACSS reticle. I think the higher MCarbo rear sight will help.

Here is my cart, so far!

[KEL-TEC SUB-2000 Bolt Tube Cover]

[KEL-TEC SUB-2000 Recoilless Charging Handle]

[KEL-TEC SUB-2000 Rear Tactical Folding Sights]

[KEL-TEC SUB-2000 QD Single Point Sling Mount]

[KEL-TEC SUB-2000 Optic Mount]

My question is: While I plan to fold the MCarbo rear sight out of the way (one of the reasons I want it - can’t fold the stock rear sight down), how will it cowitness with the aforementioned Holosun optic?



As good as I could do today with old eyes and the stock irons at 25 yards.


@Racer88 MCARBO has a 15% off sale going on now till 11:59 PM. Use code : AFTERXMAS


Bueller? Anyone?

Since the MCarbo rear sight is taller, how does that affect the cowitness? Is anyone here using the Holosun 503G and the MCarbo rear sight?

And since I’m here… how difficult is it to install the MCarbo rear sight? As a point of reference (regarding my manual skills), I build P80s that function flawlessly. :slight_smile:


If I did it, anyone can. Tight, but not overtight. Add a smig(?) of blue loctite.

Welcome to the Brotherhood :+1:


Here is what you can do. I also drilled my OEM sight to open it like the one of the choices that can be made on the MCARBO.

If you combine the correct mount and red dot you can co*witness both sighting systems


Is that the factory rear sight? Or MCarbo? From what I can tell, the factory sight doesn’t fold down when the rifle is unfolded.


Look at the two pictures of side of my SUB200. rear sight up/rear sight down. Cutting those legs gives you the choise of position when barrel is deployed !!!
Yes there are 2 legs on either side of barrel hinge. there are slots where the rear sight folds when folding the barrel those control the deployment of the rear sight, at least on the ben 2’s. you see the pictures. Follow me you can take a very sharp knife and get rid of that control and it lets you decide rear sight up/down/
If you look st the home page of this forum, you will see a new thread about info for Sub2000’s
read read read there are a bunck og great info related to love of the SUB2000.


Thanks. I still want to be able to fold the rifle. So, it looks like the M*Carbo folding mount is the best thing on the market.

It’s an interesting piece (S2K), for sure. I just got through spending $$$ on kitting out the Shockwave. Then my wife drops this on me! LOL! Here I go again! At least I can blame her. :sweat_smile:

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My S2K is a “gen2” and that is a factory sight !!!

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I knew nothing of an MCarbo folding sight until about 10 minutes ago. I mad mine foldable 4 years ago…


I just re-read your response. When you fold your OEM barrel to the folded position the OEM sight automatically folds with the barrel !!! When you unfold the barrel the rear sight on my “gen2” deploys to the READY possession and stop at the point (because the slots on either side of the hinge STOP THERE). By removing the little legs gives you a folding rear sight THAT IS FACTORY height.
Now the things I am saying here are only my experience with my own firearm.


IMHO your in a good place right now.
I had a long and interesting learning curve, both in upgrades and venting targets.
I am now able to hit 6 inch steel plate, benched, with factory sights at 100 yards(compensate for a 1 foot drop, with 9mm same Blazer rounds). You can definitely achieve this, just need to run a lot of rounds. That is what worked for me. It get some getting used to and yes, black centre on white background target worked the best for my eyes to focus on. Suggested by others was to drill the rear sight hole a bit larger, but I never got around to it. The cheek weld is best acquired with the bolt tube cover, I strongly recommend it.
I wanted to stay as light and compact, maintaining the folding feature.
Persevere, your doing well.
BTW, I am by no means the best for advice on this and other topics, just a few thoughts to share with you on the learning curve.


Thanks. What about painting the front sight post with hi-viz orange? I was thinking about doing that today. It will still be fuzzy to my 59 year old eyes. But it would no longer be black on black. Opening the aperture in the rear sight would be an easy mod.


Hi Racer, not sure, never did that or heard of doing it with any colour.

The AR style front sight works good, just need to figure it out and remember to tighten the screw after each adjustment of it might wander off on you, others will fine tune what I am referring to. Ounce your sighted in at 25 yards I’d suggest not changing it to soon unless you do feel it needs adjusting again. As you know there are several factors to consider.
Stick with the Blazer or same ammunition over several hundred rounds, that is what I did and eventually got on target with fairly good groupings then reach out further than 25 yards.
My eyes are crap so I hear you there, eventually you will find that sweet spot, comfort, feel position that works best for you. ALSO, the SUB2K is not prone position friendly. I could not get that fire position to work for me.

Can I suggest joining in on some friendly shooting with us, see the banner at the top of your post here and reach out if you have any questions.


Ironically… making the rear aperture SMALLER will make the front post sharper - just like a smaller aperture in a camera lens increases “depth of field.”

But it (obviously) reduces the light transmission, so it works best in bright light.

Thinking out loud, how I could make the rear peep sight aperture smaller (with some kind of insert). Hmmmm…


The downside is a small aperture may be good for bullseye precision shooting… but not good for defensive shooting.


I’m agree and disagree.
Check out some of the post under the SUB2K.
It’s difficult enough to get a fix on the black dot lets say.
I’d suggest just persevering as it is or upgrade as others have mentioned.
I’m just an old school, who works with what was factory. So many great upgrades, do not hesitate to upgrade on the other options, they are upgrades tried and proven. I’m sure they will perform just perfect for you.
You will have somewhat limited options with maintaining the folding feature otherwise the slate is open to so many upgrades.
I’m just a practice creates improvement person and other on the forum have coached me well and supported my perseverance with some fantastic advice I’m very grateful for.
Best of luck.
BTW, you can definitely expect a 1" grouping with mag dumps at 15 yards, standing, no problem.


I bought an AR15 hi viz orange front post, and it made a huge improvement on sight aquisition ! Whether you paint or replace, it will probably help!


All my firearms, pistols and carbines, are painted Fluorescent Orange. It shows up better on white or cardboard colored targets.

You can buy this at Michael’s or any craft store for@ 99 cents. It is water based so it scubs right off. The bottle will last for generations to come.


I had a day-glo (fluorescent) orange paint pen and applied it to the front sight post. Not elegant, but I think it will help.

I also just ordered a Blitzkrieg Components Precision Chevron Front Sight Post with orange stripes.

I’ve got some ideas on how to improve the rear stock sight aperture. Stay tuned for that! I’ve got to wait for some tools to come in. This could be pretty cool.