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!

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

1/31/2015: We are now out of KAC MK12 quad rails for the MOD1 builds — so, if interested, please do contact for a place on our wait list.  KAC says 2-3 months (which has come and gone — they have produced another run of the rails but your guess is as good as mine as to when I will receive any as the runs are intermittent…) so more MK12 rails will come available someday....  We can still build MOD0 uppers as those parts from PRI are readily available.  

We can also continue to build a best quality SPR upper using an alternative rail system, if you wish.  Thoughts for rail sources include KAC URX or keymod rails; Daniel Defense; Centurion Arms; Ranier Arms…..upper pricing will vary depending upon rail costs.  Just contact me and we can work out a plan.

We are out of DanDef MK18 rails on hand and do not seem to be available commercially anymore  so, MK18 MOD1s are no longer available.

Accuracy International has discontinued their AICS 2.0 line and that means no more MK13 MOD5’s can be built incorporating that stock.  We can build a 300 win-mag rifle using their AX chassis or go retro and use a McMillan stack 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