M*CARBO Brotherhood

New Collar Design On SUB2000


All you have to do is put the new collar on, it’s not going any were because it snaps in place, when you go to take you can feel a snap there is no real pressure on the collar. I have 2 sub’s 2 different collars. When I did the trigger job I did not use the Loctite 380, I just put it back on while I was waiting for the trigger bar, after 300 rounds all I had to do was give it a littlr turn to snug it up. With the plastic collar it snaps in place you could use blue Loctite if you like, but I like the idea of the new collar because you don’t need a special wrench to take it apart. The only draw back you can’t use the Mcarbo sling mount with the new collar. Here is a FYI Loctite makes a clean up solvent the number is SF 768 it is expensive. Amazon has a 1.75 oz bottle for $37.93 This will remove the old glue. I use it on the all the trigger jobs that I do. When you reassemble use the 380 sparingly.


Thanks, but my new plastic collar nut must be FAR looser than yours. It turns into place, like it “should” snap, but then keeps turning. It does not lock into place, like the nut is broken or too large for the mount. I repaired the rifle myself with a threaded pal nut. (like the old collar, but fits the new receiver). The new plastic setup I have is total junk. It does nothing but cover the receiver tailpiece and fall off with each shot. Fixed it, but I shouldn’t have had to. Love the Sub2K design, not impressed with the materials.


I’m sorry you have had this problem. I would have called Keltec, explained the problem. I would think they would send a new collar & if that did not work Keltec could send you parts S2K-410 L&R GRIPS. Or they would send you a return label for them to replace the parts. If you can take a picture of the grips were the collar locks on.
I’m thinking some thing is wrong.


Don’t use the blue medium 242 Loctite stuff. It eats a lot of types of plastic. Use the Black Max 380 stuff that Kel-Tec used on the old style collar. It works fine.


Thanks MadDog. I did contact KelTec (twice), explained the situation in great detail, and Vicki said they would not send parts, told me that a gen 1 collar nut would not fit on the new receiver, and wanted me to return the rifle for warranty work (and I had to pay the shipping). I sent a picture and it didn’t seem to impress them. The only thing that is wrong is that they think the new setup works fine. Whatever happened, my Gen 3 collar nut didn’t hold at all. For what its worth, I borrowed a friend’s gen 1 castle nut and it DID fit over the Gen 3 receiver halves, so I ordered a castle nut from KelTec and am looking forward to using my single point sling mount once I crank the old style metal nut in place.


Please post a picture of what the extension of the gen III receiver, where the castle nut secures it.
A suggestion would be to see if you cut 2 slits in the new castle nut will help to secure it once you have sling mount in place.
I would suggest if castle nut will go over the extension on the rear of the receiver and you can fit the sling mount over it and the sling mount will securly anchor it after you cut slits in the castle nut DO NOT USE GLUE That way if you ever want to go back into the grip to do anything you can easily do it and put it back together.
Does anyone out here know if the GEN I andGEN II are the same size.
If they are not the same size which is smaller?

I have a GEN II and use the PSM castle nut with the PSM sling mount looks like this, no glue required.
I will never go back to using glue !!!


@Wedge, do you know what the GEN I and GEN III castle nuts look like and how the GENI and GEN II castle nuts compare in size ?


Here’s the picture I sent Kel-Tec of the Gen 3 receiver. The Gen 1 metal castle nut fits over it and cinches it down tight with the action wrench.



hard to see with this pic, but nut before machining is just a slick nut on the GEN1
I clock milled 4 1/16 slots, put on vibra tite, and added a sling mount. im 200 rounds from hitting my magic “proven” number of 1000 rounds since my upgrades…


I have a Gen 2 and the metal castle nut is the same as the Gen 1. I’ve only seen pictures of the Gen 3 collar, but I know how it attaches via a twist lock design.


Cool, so it’s still pretty much like the Gen 2. The threaded metal collar will semi-cut its own threads in the back of the receiver and the 380 Loctite glues it in place. If it were me, I’d ditch the Gen 3 collar and get the metal one.


Do they ever have sales?


You say gen3. I don’t think thay have come out with gen3 it’s tey are up grading the sub 2000
I could be wrong. The last rifle I just bought a 9mm Beretta the tag on the box reads (SUB-2K9-BRTA92 BLUED/BLACK GRIP 17 RD MAGAZINE) It has the new collar on it. It is hard to say what you have & exactly what is wrong with yours. Did you say you had Keltec install up grade trigger job?
Do you live in the central time zone?


What are you asking about ?


does the extension on the receiver have a grove that the castle nut slides up on and then you twist ?
Can I get a larger picture ?


Scott does the picture from @ezslim look like it has a grove that a “nub” in the castle nut slides up on then twists to lock ?


From what I’ve seen before, it looks like it does to me.


you know hoe much hassle it is to have to glue a castle nut on then wait for the cure then if you want to go back inside and do something you have to go through that again.
I love the one screw off and back on. I think @triggerhappy machined his own GEN II) castle nut and reinstalled with sling mount, clamping it together. I could be wrong but I am looking for it in the level 3 loung right now.
@Wedge you were the one that turned us on to the PSM castle nut do you think that would work in place of the new castle nut ?
I know I really like the PSM product.

If a GEN II castle nut would fit over the “NEW” extension then I would bet that it would work on the “NEW” extension.
@ezslim, do you have a caliper that you can measure the diameter of the extension. If so measure across the extension NOT WHERE the the indent is. Take a good picture of measurement and post it.


I’ve done it a few times and it really wasn’t that big of a deal. The MCARBO armorer’s wrench makes things easy.


Why not just machine “crimp slots” in the old collar nut ( using the " threads" as splines) and install the sling mount doubling as a retainer sleeve?

That’s already been done.


Have you tried these ?