MK12, MK18 Upper Builds and MK13MOD5 conversions


Offering a variety of configurations of the MK12 and MK18 battle platforms ranging from the basic upper to the complete package including optic, suppressor, bipod, and accessories.

And, now, the MK13 Mod5 300 win-mag rifle conversion!

(4/26/2018) Just finished these uppers up for an Army customer — 2 MK18-like uppers to his spec and a 14.5” recce with Douglas SS barrel…he’s used my uppers in the mideast — proud to think they were used in our continuing war on terrorism…

3/28/2019 update:  I’m old and am looking to free up some time from HCS…I will continue to build MOD1’s and MOD0’s — I will not stock the MOD1 “add ons” such as sling adapter, buis’….  I will still sell suppressors and NF scopes as well as BlkHills ammo and our Douglas barrels.  I am available for custom builds. I may not answer your email quite as quickly as I try at present — I will get back to you and may get back as fast as always…depends on what I am doing….and that is the point — time to smell some additonal flowers…but still enjoy comms with you all — you have been great customers…so get in touch if you have a need and we’ll see what we can work out 

A recent email (3/2019) from a customer was full of some good news: 

Just wanted to report that after roughly 18 months my MK12 is still as precise as when it was new. 

Interestingly enough, I recently discovered that the rifle really likes the PPU 75gr round. I’d been almost exclusively feeding it a load developed by a local guy that I’ve been working with for 10+ years. (Hornady 75gr HPBT Match; 2650 fps) On a whim I ordered a case of the PPU (and was admittedly skeptical & prepared to be disappointed) and had stellar results. I’ve had many sub 1/2 MOA groups at both 100 & 200 yds and a few 3-shot groups at 100 that were one hole. I was shocked. 

Just thought you’d enjoy the feedback after 18 months and countless rounds.

05/30/2014 update and really cool news — good friend of High Caliber, Larry Vickers (, invited us out for an interview on his youtube video series: I think Alan did a great job in the interview while I worked away …here in Indy

                                     US SOCOM Small Arms Replicas by High Caliber Sales  

We are out of DanDef MK18 rails and do they not seem to be available commercially anymore — so, MK18 MOD1’s are no longer available (unless you  have a DD rail to send us…).

High Caliber Sales is a Title 1 and Title 2 dealer who can provide you the very best, tried and proven, weapon systems and components.  

We possess a unique insight into the original request for the development of, and the refinement of, the MK12 and MK18 SOCOM platforms.  

Our initial offerings are the MK12 MOD1 (or the Mod0) SPR and MK18 MOD0 carbine uppers.  These uppers are manufactured to mil specs using the same manufacturers and contractors as used by Crane Nav/Sea in southern Indiana.  Assembly  is performed by an individual integrally involved in both the design of these weapons and their construction.

Select accessories, including signature reduction devices, are available and these options are the same components as tested and evaluated for use on the Crane offerings.

You can rest assured that what you are purchasing is the equivalent of what the US Armed Forces are fielding.

We are dealers for Aimpoint, Nightforce optics, Knights Armament Company, Ops Inc., Gemtech, Lewis Machine and Tool, PRI, Blue Force Gear, and Harris bipods.



© KJ O'Neill 2012