Re: PWS MK214
Whoa Boy... BM, you went down that rabbit hole... LOL
I am by NO means a GUNSMITH, or a GUN EXPERT, or even a COMPETITIVE SHOOTER. I'm just a guy that has done a butt load of tactical shooting, and hard use on top of a lot of training. So, what follows is my own observations... and not the bottom line.
Ok, here's MY take on it, and my experience... your mileage may vary. I have shot AR's for the better part of 25 years in my Military Career. I have trusted my life to the M16 / M4 series of rifles on multiple rotations in both theater of operations, and the "free float" issue has never been an... er... issue.
Handheld rifles are just that, hand held. It isn't until you start getting into prone / bipod type shooting that barrel harmonics come into play.
As a cartridge is fired, the gas expands, pushing the projectile down the barrel. Have you ever watched a rifle being fired in very slow motion? Some barrels look like noodles...
I won't go into the math, or equations, but lets just say, the shorter the barrel, or the FATTER the barrel, generally, the stiffer it is. This in terms of harmonics.
While there are a number of factors that determine the accuracy of a rifle barrel, one of the more critical elements is its stiffness or rigidity. Obviously the larger in diameter a barrel is, the stiffer it will be. Almost as obviously, as the length of a barrel increases it becomes more limber. I call this the "noodle factor".
So, there is a trade off of sorts if our goal is a stiff barrel, and as a result a potentially more accurate one. If we are limited to a barrel of a certain weight, as we are with a varmint or hunter class rifle, the compromise becomes length verses diameter.
In the case of an AR platform, even a Direct Impingement rifle has a gas block stuck out on the barrel somewhere. This is a necessity for the rifle to function. You must divert the gas back to the bolt, to drive the action. Even with a piston gun, you have to divert the gas to drive the piston. So, we can not escape this metal out on our barrel.
The gas tube also contacts the upper reciever. This is of little consequence... but, it can still have some effect in harmonics.
On a bolt gun, I can see the need for a bedded action and a free floating barrel. To an extent. You want to make sure the barrel is FAT enough, and SHORT enough to be able to withstand the noodle efect of the round passing through it. A 30 inch floated barrel will oscilate more than a 20 inch floated barrel of the same diameter. This is a non disputable fact.
When a cartridge is fired in a chamber, the barrel undergoes many stresses. It begins to vibrate when the firing pin starts its fall and these vibrations increase dramatically from then on. During recoil and while the bullet is still in the barrel, the barrel will whip vertically. This happens because the thrust axis of the rifle is above the centerline of the stock. During recoil the barrel comes back and up. Minutely, of course, but the movement IS there...
The muzzle will lag behind the rest of the barrel in this movement and the vertical whipping motion is set up. While these vibrations of the barrel are very small, they do exist. The stiffer a barrel is, the less the muzzle will jump around. This brief description is of course an oversimplification of the dynamics that take place, but they do point out the type of barrel movements occurring and why a stiffer barrel is more accurate. Hence the inception of the "bull barrel".
Now, is free floating tubes a MUST when it comes to accuracy on an AR platform? Yes and No. We are limited to the overall diameter of the barrel on our AR's... because WHO wants to carry around a 20 pound AR? So, in all things equal, an M4 profile barrel, will oscilate the same no matter if it has a floating tube on it, or the US GI Issue KAC rails that I humped over the mountains for many moons.
Where floating tubes DO come in to play, is barrel torque being induced by loading the bipods. Let's say we are talking about a 24" barrel (INSERT NAME HERE) AR-10 style platform. You have a heavy contour match grade barrel in it, and it has a rifle length free floating tube on it. In terms of shooting prone, you can load into that bipod heavily, and since the torque will be transferred into the reciever via the barrel nut, induced torque will be minimal.
In the case of the PWS series rifles, they are intended to be hand held battle rifles. I am shooting mine off of bipods, and find that they are every bit as accurate as I expected them to be. They are using a very quality barrel, with a chamber cut to tight tollerances that still afford reliablility. The gas block on the PWS rifle is HUGE, and this is due to the size of the piston / op rod that lives in the upper gas tube. They wanted to keep the upper rail standard with all other AR type accessories, and not give a wonky cheek to stock weld.
It is very possible to load the MK2 series rifle with a bipod, lean into it, and cause the groups to open up. But, knowing the cause and effect of this, compared with the absolute softest recoil I have ever felt on an AR-10, lack of muzzle jump, there is no need to load the bipod that I have found.
Knowing that, you can glean enough accuracy out of this rifle to be competitive, and rely on it to shoot when you pull the trigger.
Knowing is half the battle.
I hope this is clearer than mud, and these are my own findings. Not to be taken as the gospel.
I do emplore you though... find someone that owns a GAP Bolt gun, or an Accuracy International... and ask them to let you clamp a nice chunk of medal about 14" down the length of their barrel... see what they say to you.
Bolt guns that are bedded and floated, make sense. AR's... well, that's apples and oranges.
Cheers!!!
