14-FIVE-16 Barrel

Creating a Street-Legal Colt 14.5 Inch M4 Barrel Assy
(16 inch barrel)
"Pinned and Welded"
This is the central piece to creating a very authentic looking US Military 14.5 inch M4 barrel assembly which is legally 16+ inches in length, using the ATF measuring method. We designed a custom SA M16A2 compensator / flash-suppressor with reworked internal lengths and geometry, measuring 2.050 inches, while maintaining the 1.750 inch long US Military appearance. The rear section with the “extra material” allows us to accurately machine each part to its respective barrel and achieve top-dead-center timing with 50-75 ft/lbs of torque and a final legal length of approximately 16.031+ in. (fractional: just over 16 and 1/32 of an inch).
The SA M16A2 Compensator is manufactured from Niagra-LaSalle 1144 Stressproof steel, H/T 40-43 Rc.
Built to last.
Colt LE6920 barrel, length = 17.468 inches
Colt/SA M4-SE barrel, length = 16.043 inches(flash suppressor pinned & welded)
Colt M4 barrel, length = 15.879 inches
All measurements were taken using ATF methods with flash suppressors installed - exactly as pictured.
(NOTE: All 3 barrels have the same diameter step behind the flash suppressor - 0.700 in.)
The difference between the Special Edition barrel (center) and the Colt/US military M4 barrel (bottom) is only 0.164 in. or less than 3/16 of an inch (0.188 in.) in real life. Needless to say, this is a nice way NOT to spend $200 on an NFA tax stamp (save that for your MK18) and it is legal in States where class III items are restricted. (The actual SE barrel in the center was machined from an LE6920 barrel exactly like the one above.)
Here is a Colt barrel and SA M16A2 compensator which have been precision machined to interface perfectly with the required torque. This barrel assembly has also been carefully milled for a hardened pin which was press fit into the compensator and barrel, followed by a small TIG weld.
As you can see, after pinning and TIG welding, the new M4-SE barrel assy requires further machining, grinding and finish work to complete its upgrade. These steps must obviously be followed by the correct military-grade phosphate plating (DOD-P-16232F Type M) to refinish the entire barrel assy. (SS800) This SE barrel in the above photo is nearly ready for plating.
After plating and lubrication - ready for assembly
ONE ongoing problem for us here at SA: Requests to install numerous muzzle devices from other manufacturers – SureFire, AAC, Knight Armament, Daniel Defense, etc, etc. While these are great companies with many fine products, here is the DILEMMA – Most of these items are made from exotic materials and various types of stainless steel, which cannot be phosphate plated (US military finish) – that means they will turn completely SILVER. (Special welding is often required too). Most of these parts have been finished using a variety of nitride methods. Our company has no problem installing special muzzle attachments onto short barrel rifles (SBR’s) and select-fire weapons, although special machining is sometimes necessary.
BTW – the US military crush washer is also made from stainless steel, type 17-4. This is actually a corrosion resistant aircraft part (NSN: 5310-01-475-9652) with a special black-oxide finish. (It is called, “washer, recessed”). No, we are not installing these on pinned-&-welded barrels either. Don’t ask. Yes, we made a SMALL run of hardened tool steel shims that looked exactly like the real crush washer, for a few projects. We are not doing them again – the $100, multi-faceted, precision-ground, washer has gone out of style.
All Finished – Colt M4A1 SOCOM upgraded with the RP – Fire 4 Effect