Am I Nuts for Wanting to Build a Mk18 Mod 0 Pistol?

Basically what the title says. The more I research and see of the Mod 0, the more I like. Small and maneuverable, yet keeping a lot of the classic lines of the AR/M16. I also like it over the Mod 1 because of the Aimpoint and fixed sights. Of course, it won’t be 100% because of the lower, the trigger guard (I’ve switched to Magpul Enhanced almost 100%), the rails (don’t really need them), and the lack of a stock… but it’ll be close enough for me.

Anyhow, the bits I was thinking of using:

  • Whatever lower (locally, Spikes, YHM, and Noveske seconds are available)
  • LMT fixed A2 rear sight
  • Aimpoint Comp M3 on a Larue LT-150
  • A1 grip (or a de-humped A2)
  • G&R Tactical LPK w/ MagPul Enhanced trigger guard
  • Spike’s pistol buffer kit w/ ST-T2 buffer (sigh I know, I know, but it comes with it)
  • LMT 10.5 Basic upper
  • LMT FA bolt carrier assembly
  • BCM GFH (not sure if I want another Mod 4, or go with a Mod 5 for this one)

After having it for a while, I’m probably going to go ahead with the SBR paperwork and toss on a milspec RE, H2, and SOPMOD, but an extra $500 for the stamp and accessories is not an option right now.

So am I dumb for wanting to do this? I already have a 20" and 16" middy, and this fills a niche in the collection. What gives me pause is:

  • I’ve heard the best ammo for such a beast is Mk.262 or any good 77gr, and that the piles of 55gr that I have in various flavors are too ineffective and inaccurate to be of any real use.
  • I know next to nothing about gas port sizes and requirements for short barrels, or the reliability of such a… limited-size system. If I go whole-hog I’ll be needing a suppressor, too, and that just drives up the uncertainty even more. I guess what I’m asking for now, is, will the 10.5" barrel with carbine gas run as reliably as my 20" rifle and 16" middy? What will a suppressor make it do?

Any input is appreciated. I’d hate to spend a ton of money on a bad decision.

And of course, since pictures are always fun, one I found of someone else’s Mk 18 that I ran through MS Paint real quick for an idea:

Yes. Get an SBR.

Can’t be one ofthese. What the heck is a Mk18 Mod0 anyway?

Never mind. I got it. One of these.

I’m thinking of doing something similar. Reason being I crave a daniel defense mk18 upper and my Illinois elitist master rulers deny me the chance to apply for a stamp for an sbr. Plus I have an extra stripped lower in the safe crying for attention and a pistol buffer tube laying in the parts box from a previous build.

If we ever become a free state I would then sbr it.

As long as your are going to sbr it I wouldn’t say you are nuts but I’d start the paperwork as soon as possible.

Also they are out of stock right now but aim sells the spikes 10.5 upper for 500 bucks with a fa bcg, moe handguards, and their st buffer. Haven’t read anything bad about them, might be a way to save a few bucks.

I did mine with a complete lmt lower and lmt 10.5 upper. It has a bcm bcg because I had one sitting around and didn’t care if it was a complete lmt rifle or not. It has a kac factory second rail on it. First upper I had issues with the barrel keyholing 55gr rounds. LMT had really good customer service and got my upper repaired pretty quick. They re installed my rail(I know very easy) and redid the flash hider with peal washers for my halo suppressor. I want to say I got it back in like 10 business days with a holiday in the middle. Can’t complain.

With it’s halo. BCM 20inch rifle above it.

I stare at the aim surplus spikes 10.5" specials also. Then I think that if IL did get reasonable gun laws and I could sbr, what with the cost of a stamp and all I would probably regret saving $300 by not getting a daniel defense.
Instant savings but no gratification later.

^^^^THIS^^^^

I don’t get it. Why would you not want a stock?

As stated in the OP, but explained a little further, the cost and wait time for SBR paperwork as opposed to having a working firearm much sooner.

On the plus side, turns out there’s an engraver in town that does the work to spec, while you wait, for $10 and does an amazing job.

I don’t think it’s crazy but it is like taking the two legs of a right triangle instead of the hypotenuse. Personally, I wouldn’t want “pistol” stamped anywhere on my SBR lower, but that’s just me.

Your lists of parts isn’t bad and would cost you some change anyway. Buy a quality lower, get it engraved, put in the paperwork, and while you’re waiting for it to come back, save up the money to buy the upper. Good things come to those who wait.