A rifle barrel is like a tuning fork, in that it vibrates during firing, and you’d like to have the correct and consistent tone with each and every shot. In theory, anything that is either touching or putting pressure on your rifle’s barrel will affect its harmonic vibrations. A simple change in temperature or humidity with a wooden gun stock is a perfect real life example—changing pressures at different points of the stock caused by natural expansion (humidity and heat), contraction (cold weather), or whatever (sling mounts and bipods) can change barrel vibrations (barrel whip) and your ammo’s point of impact from trip to trip…or even during the same trip, depending on the volatility of climate conditions.
Whether you use a sling or not to steady your shot, a bipod or a sandbag rest, all of these conditions can change the relationship of your weapon’s POA (point of aim) versus its POI (point of impact). The majority of match grade rifles offered these days will employ some sort of free-floated barrel to increase the accuracy potential of the weapon, in conjunction with either a synthetic or glass bedded or pillar bedded wooden stock.
Free floating a barrel, where the barrel is attached to the receiver and the receiver is attached to the stock, but where no point of the rifle stock touches the barrel, usually keeps the vibrations of the barrel uniform during a repetitive string of shots. I spoke to Savage Arms Sales Manager Bill Dermody, to get some insight on the benefits of a free-floated barrel as it pertains to consistent shot placements. “The Savage AccuStock goes a long way in keeping shot groups consistent,” he said, describing their free-floated barrel strategy, “and is based around a heavy duty aluminum lattice framework. This aluminum structure is actually placed in the mold and the stock’s nylon synthetic material is then injected and formed around it. In addition to rigidity, the AccuStock provides what we call ‘three dimensional bedding.’ The action is physically secured on three planes: up/down like most other systems; forward/back; and even left/right. The space between the sides of the aluminum frame is actually slightly smaller than the width of the rifle’s steel receiver action. So as you tighten the connecting bolts, the action forces itself down between the side rails that flex outward, making for a very tight, sure and consistent fit. The result is that the barrel is totally free-floated with no external influences (like uneven stock pressure, slings, bipods, etc.) to adversely influence barrel harmonics, thereby offering the shooter greater accuracy potential.”
Another recent free-float experience that I had courtesy of a GW product review was with Mossberg’s excellent MVP Predator bolt action HBAR carbine. All Mossy MVP family members employ a free-floated barrel that is achieved via a pillar bedded action, where the beef of the carbon steel receiver is through-bolted into a pillar bedded polymer insert that is seated in the magazine well of the wood laminate stock. No part of the tube touches the stock and you can slide a dollar bill in a hollow recess under the barrel that runs from the front of the foregrip aft to where the recoil lug cuts off your path.
Photo by John N. Raguso