M*CARBO Brotherhood

Red Lion Flip Up front sight. Anyone have the skinny?

Well. The one thing that I really can’t stand about my newly upgraded S2Ks are the front sights. The HiViz fiber optic posts I installed are an improvement, but not much. I don’t see any indication that MCARBO will be coming to the rescue any time soon with a quality folding front sight, so I am considering the Red Lion R12 folding front sight for both of my guns, at least until MCARBO comes up with something better.

  1. Has anyone done the install? I have the muzzle break on both of mine and I assume I have to go through the hassle of taking these off to put the RL 12s on.

  2. If you did the install, was it worth it? How do they shoot and are they easy to adjust? Do they hold zero?

  3. If they do what I think they will, I should be able to put a higher riser on my RDSs so that I can be more heads up and not have my cheek on the tube (yes, I have the MCARBO bolt tube sleeve). A good co-witness is great, but folded front and back sights mean a clean scope picture that I prefer, especially on a higher riser. Is this a correct thought?

4). Are there any other options you can think of? I really think that Chris and crew did a great job on the folding rear sight and put them on both of my guns, but it really doesn’t address the toy-like piece of cheap plastic crap on the front of the gun. I love using iron sights, prefer it really inside 50 yards (Getting closer as my eyes get older :confounded:), but I really don’t want to hassle with trying to get those Factory “things” right when a decent RDS will be much more effective.

Any information y’all can provide will be appreciated!



@MOLON_LABE I have the RL folding front sight installed and believe it is worth every penny, that stock spring loaded front pivot block had to go. It is a high quality piece with easy adjustments. The ability to fold the front and rear sights out of the way and clamp on a red dot with QD mount is why I purchased it, never really understood two other sights in my way like in a co-witness set up. Although with the RL front sight and Mcarbo rear peep I actually like shooting my S2K without a red dot. The RL sight screws into place like the stock front sight but no need for any type of Locktite as there are two robust clamping screws and a small set screw that hold the RL sight in place. It is the same height as the stock Kel-Tec front sight but folding it drops the overall height by 15/16".

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Can you post a Pic of it… I’m not familiar with that front sight


Thank you for the info! Last question, am I going to have to take the muzzle breaks off of the S2Ks to get it on? It looks like the RL won’t open wide enough to go over the breaks. My .40 uses a lock washer for the break and that is not as big a deal as having to get crush washers for my 9mm From MCARBO and figuring out how that works.

Oh, and do you like the post that comes with the RL, or can it be switched out with a fiber optic or trijicon sight and if so, would it be worth doing it. My eyes seem to have more trouble with keeping that front sight “clear, sharp and focused“ as I get older.


Edit to add. I will be able to still use the muzzle breaks after I put this on, correct?

Edit #2 to add. I thought I read somewhere that the RL front sight has fit issues if you have installed the RDL (Rapid Deployment Latch), which I have on both guns. True?

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Better than a pic. Here’s the link, and it looks to be on sale right now?

Red Lion Flip Up Front Sight


@00Buck @MOLON_LABE It uses standard AR front sight posts so can be switched out. You have to take the break off to install it. The new latch is longer than the stock one so folding the S2K with the front RL sight folded it just barely hits the back side of the new latch. I keep the RL sight flipped up so when I open S2K both sights are already up and ready to go.


@MOLON_LABE New latch with RL sight folded.


That is pretty cool. I might just have to try this sight on my newest S2K since it still has the stock sight on it. I’ve epoxy the sights on my other S2K 's.

Did the MCARBO barrel jaws fit properly with the RL installed for the muzzle break install. It looks like you have the crush washer.

I am planning on taking the fore end off when I do the install anyway as it looks like it will give me more room. I am going to replace the stock fore end screws with the MCARBO fore end screws. I mean hell, why not? LOL


There is a thin locking nut and a shim, no crush washer.

Just watched videos on that sight install, looks fairly easy to do. I have that same muzzle break and like it. I run this Fortis brake on one of my gen2’s, works pretty well.

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@00Buck @MOLON_LABE Yes, it is on sale right now for $85, I paid the $96.

Oh sweet :+1: I’ll be picking one up today

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While I primarily use a red dot, the factory front sight is horrible and the Red Lion sight seems to be the best replacement available. I personally think it is overpriced but bought it anyway and am happy with it. The installation was easy but I had no muzzle brake to remove or reinstall. I do not have the rapid deployment latch and cannot comment on that issue.


The issue with the new Rapid Deployment Latch is that it is larger/longer than the stock latch so when you pull it back to latch the S2K or open it with the Red Lion front sight folded down it just hits the wings on either side of the Red Lion front sight post. You could probably Dremel Tool the back of the two finger tabs on the RDL a little bit to help with the hitting issue or just keep the Red Lion sight up when folding the S2K.

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Do you leave the RL sight up to cowitness with your rds

@00Buck No, if I do use a red dot on a QD mount I flip irons down but I do like the iron sight set up on my S2K so I use them all the time.


I bought the RL at the same time as I bought the MCARBO S2K upgrade kit. I was concerned about torquing the barrel to get the factory sight off; I called Keltech and asked if they’d put the RL sight on when they installed the kit, for the same $40, and they said Sure. And they did. They did a great job making sure it was in line with the rear sight (the original KT S2K sight was actually canted a bit). They also made sure to not cover up the threads on the end of the barrel. (They also found a problem with the grip while they had it in, and fixed that.) Mine clicks in when folding the rifle, whether I leave the sight up or folded down. I had an extra post here, that I got on sale sometime - it has a glow-in-the-dark green tip on it, so I put it on for fun (doesn’t really add much, but so what). I like that a standard AR15 tool is all that’s needed for adjustment. It is a nice piece of metal. I did have the clamping screws come loose, so of course a little blue Loctite and all is well.

BTW, most of the time I just shoot over the top of it all, as it’s easier than scrunching my head over the tube to line up the sights. At 25 yards, looking at center mass, I’m hitting between the sternum and collar bone. I used it in an action shooting match against guys with all of their tricked out ARs, and all of the cool electronic targets went over, no problem. Last target needed a head shot, so I took a second to line up the sights, and put it dead center. I did put the MCARBO rear peep on the S2K early on, and love it.


Thanx! Great reply. I did all the internals myself, not sure I want to send the guns in for that.

I don’t really have the room to work on anything more than the very simple (such as replacing the rear sight on the S2K with the MCARBO). Also, I think you know that tiny springs tend to shoot all around, with unfamiliar firearms, so for $40 it seemed like the best option. Since KelTec agreed to change out the front sight for no additional money, it seemed like a good bargain. I had tried (gently) to remove the factory KT front sight, but I has going to have to torque against the barrel, and that didn’t seem like a good idea. I’m old enough to have made plenty of silly mistakes with home gunsmithing, so that was that. And like I said, fortunately after I sent it in to KT, they found a problem in the grip that I didn’t know about, and they fixed it. All around, it turned out to be a good deal for me. The RL sight is a really nice piece of workmanship, even though it added another $90 to the S2K. (Of course the replacement spring/pin kit cost what, $260? I have started to make the most costly S2K ever, what with some of the other MCARBO parts - but it’s a really cool firearm to have in the trunk, and MCARBO has well-thought-out upgrades.)