M*CARBO Brotherhood

Front Sight Post Upgrade


my solution was a cowitness’d red dot - now my blind eyes can see and life is good…

on the ‘gettin’ older every day’ Gulf of Mexico


I ordered the Mcarbo “notched” rear sight (not installed yet) because the notched rear sight has a taller aiming point than the peep site from mcarbo, at least it is in their specifications and comparing both rear sites pictures. I need all of the rear height that I can get. OEM is too low for me. So I am going to need a taller front sight. Thanks for the tips. I will let all you all know how it all works out…


So, I’m new to this particular firearm, and never had an AR. Not to sound like ab idiot, but how does one swap out the front sight pin anyway? It can’t be as simple as increasing the old post and screwing in a new one can it? What is all involved?


@Jperr Yes, it is as simple as unscrewing the stock sight post and screwing in the new one. There is a spring loaded plunger under the rim of the sight post that needs to be pushed down to unscrew it. This plunger holds the sight post from turning but also allows you to adjust post up and down. Be careful so that spring and plunger don’t go flyin.


Thanx Dave67. I have the sight adjusting tool. Just didn’t want to back it off too much and screw it up. I’ll take care to watch that plunger. Thanx again.


All Things SUB-2000!

hi all

i have the usual problem w not getting a good cheek weld w the stock height stock plastic sights.

i want to buy the mcarbo, but don’t know whether to get the peep or notch.

my question is (and i can’t find it on the forum or elsewhere):

what are the Relative Heights of the two, from the point of aim, of the intended sight picture? (not the overall physical height).

to amplify, the peep would have the center of the aperture as the point of aim sight picture. the notch would ‘probably’ have the top of the notch, where it aligns with the top of the rear-sight, as typical with a pistol, sight picture.

using these two points, what is the actual difference in height, or difference compared to the stock rear sight?

i’ve called Mcarbo twice and gotten VM, and no return calls, :frowning:


I have the notched sight and it is actually a little too tall if you use the top of the notch as the aim point. I had to buy an extra tall front sight post to get the correct sight picture. If you want to use a standard AR front sight post, get the peep hole MCARBO rear sight.


this is enourmously helpful; thank you!

this is the guidance i needed


I originally went with the notch and I had issues with consistency vertically. My groups would look like a vertical line. Jacqueline at MCarbo customer service let me exchange with no questions nor hassles. I now have Peep. I couldn’t be happier. Good close groups. Just my 2 cents.


I have the Mcarbo rear peep sight and have updated my front sight to the Red Lion front sight and Blitzkrieg bright orange painted front post . I am very happy with this combination.

I find that the sights are no longer “too low”, they are usable and inspire a lot more confidence in making the shot.


this is very helpful to me…

question: according to Mcarbo, the height of this peep (their specs are very confusing as they don’t measure the height of the ‘sight picture’, ie, where your eye is relative to the stock, for each, including the standard sight, so it’s hard to know which to choose) is ONLY .08" higher than the standard sight. i’m assuming this is the overall physical height of the new sight.

if so, my q is: is this very small height change enough to really solve the cheek-weld issue? (any higher and i assume i’d run into a problem with the height limitations of the front sight, right?).

thus, do i need an optic solution?

sorry for the length, but i can’t get any help from Mcarbo on this


oh, would you be kind enough to also comment on:

i can’t seem to mount w ears, even my low profile ears. i’m wondering if going with the taller peep will alleviate this?


@500c The MCarbo folding peep center of the hole is where the top of the original factory peeps sight is. So If you have the original factory peep sights still, you can guestimate using the crest of the factory sight. I have attached a pic with both sights on the same rod so you can see the difference.

I don’t have a problem with even my large cans because my length of pull is correct. I added a stock butt pad and have the stock out to the longest length. If the LOP is too short, you have to tilt your head more sideways to get a decent sight picture. Hence your cans hit the bolt tube. With proper LOP you only have to tilt your head to 1 or 2 O’clock and your cans won’t be banging on the bolt tube.
I put an Adaptive Tactical recoil pad on my butt stock and I couldn’t be happier or more comfortable. Link to Adaptive tactical recoil pad ($25)
Also I put Bead front sight ($14) these have a longer thread so they can come up pretty tall. I also painted them fluorescent green for easier on the eye to see. I hope this is helpful. .


@Gatekeeper FYI…My MCARBO rear peep site is the exact same height as my S2K rear plastic peep sight. My S2K was purchased in Mar. 2018 and I brought this subject up once before and was told that Kel-Tec did change the height of the rear sight somewhere along the line.


@Dave67 Not to play point/counterpoint, :thinking: but I got my Sub2K in Oct. 2018 and the Serial shows it was made in May. The sights were exactly as the picture I posted shows. With all due respect to you sir, as I highly regard all you have posted and have used much knowledge you have shared.


@Gatekeeper @dave67 I don’t think Kel Tec was consistent in grabbing old and new sight inventory or that when your gun was made dictates what rear sight ended up on it. There unquestionably is a difference in height between the old and new versions of the Kel Tec rear sight as demonstrated in the post below. They also are different in design and quality and the new one is virtually identical in height to the MCARBO peep. The one in @Gatekeeper’s photo is definitely the older factory sight despite the date he purchased his firearm or when it was built. I purchased mine in August 2018 with the exact same (old version) sight but do not know when it was manufactured. I think the barrel recall may have scrambled KT’s inventory a bit.

See the post a few below that one for some additional photos.


russ, you’re terrific. you’ve completely answered my question. i think the peep will be for me. i really wanted to avoid the optic solutions entirely, and stay w open sights.

btw, i have a recoil pad on it’s way which will lengthen the LOP by about an inch.

i like your front sight solution too. this says it ships with three sizes. which did you use? (and, i didn’t realize the AR-15 would fit).

AR-15 Ball Front Sight Post (3 Sizes) 223/5.56


oh, postscript:

is the ar style front sight a screw-in proposition, or does the sight have to come off?


i should have said ‘gatekeeper’…i saw ‘russ’ in the email…sorry


Great post. I just want to add the reminder that Kel Tec raised their peep in 2018 without even acknowledging their fix. So, anyone with a pre-2018 production s2k will see relief. But folks with later production s2ks only get to enjoy a quality built piece entirely devoid of seams and flashing.