What after market piston gas system comes close to the H & K M27 gas system in reliability and performance.  I am new to gas piston AR rifles.

I have been building up Direct Impingement AR's since approx. 1992. Everything I have build up since 92 has functioned perfectly and accurately depending on the quality of the barrel I installed.

Thinking of building up a M27 replica rifle, or as close as I can get without spending the $3,000-$4,000 cost of the M27.  Thinking about a cost of $1400.00. I have everything I need except for the piston gas system/bolt and carrier.

Everything I have read leads me to think, that at this time, it would be impossible actually replicate an exact copy of the M27.

The higher rail makes HKs very distinctive in my opinion.  Cheapest route would be a TDI upper but be careful, the HK 11" M27 rail won't fit correctly on older TDIs.

My M27 wasnt that expensive (keep in mind we're in HK land), maybe $1,900 for the rifle w/o optic.  (all parts off EE).  If $1,400 is your budget i'd recommend surveying the EE and snagging a used MR556 upper.

Attached File

Caracal has some H&K and Sig piston DNA in its' design.  M-LOK rail, made in New Hampshire, UAE company.

Caracal A2 piston upper from Rainier Arms



Full30 Small Arms Channel: Caracal 816 A2

The HK M27 gas system is very similar to the G36. The hallmark of the g36 piston design is the little nipple on the front of the piston. The nipple (how do you say nipple in German?) covers a hole in the front of the block which vents excess gas as the piston moves rearward.

I know in my internet travels I have seen a similar piston system offered commercially. I searched but couldn't find it. Maybe it didn't take off or was discontinued. Maybe someone here knows what company made it?