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…

5/16/2017 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 

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 one to send us…).

Accuracy International has discontinued their AICS 2.0 line pictured on our MK13 webpage and that means no more MK13 MOD5’s can be built incorporating that stock.  We can build a 300 win-mag rifle using their AT chassis; AX chassis; or go retro and use a McMillan stock for the MK13 MOD2 look...

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.

As of 9/13/2010 we are offering the 300 win-mag MK13 Mod5 rifle as issued out of Crane Nav/Sea.

In late 2012 we began building Block 1.5 and Block 2 M4 14.5" uppers by special order.  Similarly, other custom built to your order uppers are available by arrangement.

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