M*CARBO Brotherhood

Tips & Tricks For S2k


First off let me say Happy and Healthy New Year to ALL.
Here is my New Year’s present for ALL.

Remember my MOON SHOT containment device ?

For everyone on this thread that hates chasing after the detente pin and spring here is a working solution.
I call it the MARS REENTRY device.


NASA developmental procedures.

  1. Grab a piece of hardwood
  2. drill a 3/8" hole through it
  3. Using the MCARBO armourer’s tool as a gauge for thickness cut block of wood to the same (or slightly thinner) I made mine 9/64".
  4. cut slot into the radius of the hole making sure not to go past the full diameter of the hole. File to fit safety pin.
  5. Cut “legs” to fit S2K safety pin guard.
  6. Note that the tool must be thinner than the distance between grip and inside edge of safety pin clip ring


First of all I am assuming you have the safety pin removed and are wanting to reinstall.
Here is how I do it.
1)I take something to push the triggerbar “down” into the SAFE position. then pull the trigger back and hold, this holds the triggerbar out of the way.

2) Insert safety pin in through the ejector slot side of the grip. and install the clip-ring on the detente side of the safety pin.
3) with S2K laying on flat surface locate the safety pin so hole for spring and detente is full exposed.

4) using a magnetized slot screw driver place spring in hole.
5) line up detente rod in place going in axis with detente hole and position reentry tool.

6) Carefully push pin into hole.

6) after detene is all the way in and flush with safety pin press safety pin Clip ring to the side of tool( this should secure the detente rod up against the grip hole). Remove reentry tool.

7) Push safety pin to FIRE position and install safety pin clip ring.


Here is the thing about his tool.
If Chris would modify the armourer’s tool and make it functional instead of the TOO SMALL of an opening on the end this could be made into the tool making it a whole lot more functional.


@Turmeric1 Damn good tool creation. I like it!:+1: Are you going to try and modify the armorer’s tool?


Thanks ! I beta tested it 10 times before doing the write up. It and the split collar makes it fast to take apart and reassemble.

You bet I am. Already at the millwright’s bench!!!:+1::+1::+1:

Might be ready by end of week.

By the way there is a thread that I posted pictures of FrankensteinS2K and his cousin.
@Johnksg said something about my desire to get results at distance. Here is Frankie’s effort at 50 yds.
10 shots in about 8 seconds. Using LAX reload .40 180gr.

3x Primary Arms ACSS reticle.
To get the KT420 forearm to stay secure I had to go to LOCTITE 272 on the screws that the top rail screws go into the barrel clamps


This was posted in August 2018 and my S2K purchased October 2018 had the same problem.

“I was going to start a new thread about things to look for on a new, out of the box s2k, but this might be the proper place.
I haven’t seen anyone mention these two things, and im not sure how common they are, but they were both an issue on my gen2 40.
The first. When sighted in, the front sight pin was far left of center, due to the front sight not being properly aligned straight up on the barrel.”

I loosened the front nut and set screw, straightened the front sight and re-tightened everything. then the sight pin was centered when re-sighted.


Excellent!! Would love to see your modified armorer’s tool. If Chris comes out with a modified tool or something like it, I would be glad to purchase another.


Ask and yee shall receive.

I just drilled a 3/8" hole back about 1/4" from the original slot. USed a bastard file to open up the slot and put it to the grinding wheel to cut to proper length. works like a charm! :boom:

Here is a working drawing

I know that trimming the end off the armorer’s tool gets rid of the means to remove the clip rings. I never used that function because of the risk of Unwanted Flying Rings.
I use a pair of small smooth jawed blunt pliers.
They get in close and firmly grip rings. I find it to be faster. Again, NO chance for the need call SEARCH AND RESCUE CREW


@Turmeric1 Glad to see you are continuously pushing the modification envelope brother!:grin::+1:


@Johnksg I was thinking of you the whole time!
:smiling_face_with_three_hearts:(face palm) I do believe was your response to the MOON SHOT idea.

Did you see my 50yd target ?


@Turmeric1 Yes I did…would have “liked” but of course I am all out again!:grin:


@joeFridaysays, Brian your idea of shortening the rear sight legs has a large following at the SHOOT POINT BLANK range. Over the holidays there were a lot of S2K shooters there. It got to the point one day I had to put a GPS device on my U knife to keep track of it…


@Turmeric1 I wish I could take credit or even remember where I first saw the idea. In any case it is a useful tip. Kind of you to share that knife but keep track of it my friend.


The sharing is what counts. :+1::boom:


Thanks for the heads up.


I have started carrying a collapsible silicon camping cup in my range bag. It is useful for many things, especially when shooting outdoors where items are easily lost in the grass. You can keep a handful of bulk ammo in it for ready access, use it to collect spent brass, etc. If you need to make repairs, it can help you avoid losing small parts and screws. And since it collapses flat, it basically takes up almost no room in your bag.



Here is a different way to install S2K safety pin.
After installing parts as required. When you get to the point of installation of the safety pin do this
From the ejection side of the grip take a suitable tool, pin, punch, whatever and move the triggerbar to the SAFE position. Pull trigger all the way rearward to hold the trigger bar out of the way.
Slide safety pin into place and release trigger. You are now ready to use the MARS REENTRY method of installing detente spring and pin.

See triggerbar in the way

See triggerbar in safe position and held by trigger.


For the new charging handle with locking nut, I use a finishing nail as a spacer then use masking tape to keep the handle aligned properly. Instead of using a screwdriver, I used a small amount grease to stick the locking nut to the end of the recoil spring then pushed it into position. If you use too much grease the nut will stick to the tube but you can use a screwdriver to position it.


where is that part listed as being new ?



I’d like to share a trick that I did last night while changing my small trigger spring. I tied a small monofilament fishing line to the old spring before I popped it out. It keeps it from popping up into your face or onto the floor.
Maybe other people have already figured this out a long time ago… But it shure worked for me!



this is somewhat old, so i don’t know if you follow it any longer. also, i’m somewhat confused about the various threads on this, so forgive if i’m posting in the wrong place.

i bought mine in jan '19. i had the very same issue. i did the very same thing. the result was a front sight that was so far rotated that upon closing, the sight almost rubbed against the butt-stock-notch, with a big gap on the other side. this left me mystified as to what was going on (rear sight out of alignment? barrel out of alighnment?).

i called KT and they said it should not be so rotated, and to send it in. it went in early this wk (1/14/19).

i wonder what your thoughts are on the cause of this? i will post the results of the factory look/see/fix