BRINGING THE HEAT.
Our new SPR-E barrel builds on nearly 30 years of use seen by the Special Purpose Rifle and makes a few tasteful modernizations to improve on that legacy.
It begins with a precision-drilled, button-rifled 416R Stainless Steel blank. From there, each barrel is turned to a modernized, tapered profile based on that of the traditional Mk12. There are three main alterations that have been made. First, the chamber support has been extended by 2.75". The step after the chamber support has also been smoothed out into a lengthy radius rather than the traditional chamfered step to improve the harmonics of the barrel. Second, the muzzle is cut with 5/8x24 threads rather than 1/2x28, which is more common for .22 bore barrels. Similar to the changes at the chamber support, this is done to reduce the size of the step at the last point of the barrel through which the projectile travels. The larger diameter of the threads also adds a significant amount of material at the muzzle, which reduces potential bore constriction from muzzle devices being torqued down and improves overall heat dissipation. Lastly, the chamber is cut with a shorter freebore and a tighter leade, improving the consistency of the initial engagement of the projectile with the lands and grooves of the rifling. This "5.56 Match" chamber is paired with a faster 1/7 twist rate that excels at stabilizing heavier grain-weight projectiles. Bulk 55-grain loads will still shoot just fine, but this barrel is purposefully designed around using the more precision-oriented loadings with 69-grain and heavier bullets.
One last effort we made was to reduce the size of the gas port from the NAVSEA spec 0.101" down to a much more conservative 0.093". As suppressors increase in ubiquity among the public and stocks of cheap, inconsistent steel cased import ammo dry up, we wanted to ensure that rifles using our barrels will function optimally under the prevailing use case of today's modern shooter. The port is optimized for use with 5.56 NATO spec ammunition. For buffer recommendations, click here. Whether using a modern low-backpressure or traditional baffle stack can, you will not encounter issues stemming from dramatic over-gassing such as excessive component wear or arduous double-feeds when using a standard fixed gas system. Should you be using weaker loads, there is still enough flexibility to step down to a lighter buffer or spring to ensure reliable cycling.
The standard configuration comes with polished feed ramps and a single dimple stack opposite of the gas port that is compatible with low-profile gas blocks with set screw centers anywhere between 0.430-0.500".
The SPR-E barrel is designed from the ground up to capture what made the Mk12 so effective with modernizations to suit the needs of today's precision shooters.
