The traditional wisdom goes: Lightweight or “pencil” profile barrels can shoot great – just so long as you don’t get them hot. After a mag or two of heat is dumped into your lightweight build, your point of impact (POI) will probably shift by several minutes of angle. If you don’t like it, then you’d better go for a thicker profile or learn your holdovers, because that’s just a fact of life with pencil-thin tubes.
Or is it?
Faxon Firearms claims their stress relief process frees thin profile barrels from the uneven stresses that cause POIs to shift when a barrel is put under thermal load. Ian and Karl of InRange TV chose Faxon barrels for “What Would Stoner Do?” project to reduce the weight of the modern fighting AR-15, on the basis that if Faxon’s claims were true, it would allow them to reduce the weight of one of the rifle’s heaviest components – it’s barrel – without compromising its rapid-fire performance. Yesterday, the duo published their test of the WWSD rifles and their Faxon barrels on YouTube, and the results were extremely surprising:
Faxon, it seems, knows a thing or two about barrels. Ian and Karl’s test proved out Faxon’s claims, with the WWSD rifles experiencing significantly less thermal shift (possibly none) than the legacy SP-1’s M16A1 profile barrel. Truth be told, I was extremely surprised, since thermal shift is something that has plagued lightweight barrels for decades. Thermal shift during extended or rapid strings of fire is the primary reason why heavier barrel contours are now favored for military applications, for example (the other, less important reason is raw thermal load – barrels will eventually give out under too much heat, and heavier barrels have more mass to absorb heat than light ones). A lighter barrel that maintains its POI during and after rapid fire would potentially allow a significant reduction in weapon weight, to the tune of half a pound.
With the Battle of Wanat and experiments demonstrating the structural failure of lightweight barrels under extreme heat loads still fresh in the minds of many, the likelihood that the next infantry rifle will have a super-thin pencil profile barrel is probably fairly thin. For the civilian shooter looking for a lighter weapon, though, pencil barrels that do not experience thermal POI shift should be extremely interesting.