Free float or pressure points

Splatman, long heavy barrels have hung free floated from one of the least stiff, easily bent commercial actions since the 1960's. Shooting as accurate as modern single shot very rigid actions do these days with the same size barrels.

All receivers bend some amount regardless of what the barrel weighs. But it's the same for every shot fired.
 
Actually receivers bend more under heavy
bull barrels when completely floated.
Custom actions will usually be
threaded deeper to support such
barrels. Glass bedding also helps
to reduce the amplitude of the
harmonic way. Keep in mind that
that although pressure points will
mitigate the amplitude the frequency
of the wave will increase. This is
usually preferred as it makes fine
tuning a load more easily done. I
do recommend completely free
floating a wood stock since wood
swells with humidity. For fiber glass
stocks I usually free float the barrel
and then glass bed the action and
the barrel since fiber glass is
completely stable. I would treat a
synthetic stock similar to wood.

splatman
 
If you think fiberglass stocks are perfectly stable, you must not be familiar with the problems fiberglass stocks had on match grade M14's and how they bent from sunlight on one side. Zero's also changed from hot to cold ambient temperatures. They were no different that synthetic ones. Their fore ends bent enough to change the pressure on the barrel at its band the stock ferrule pressed against. But the wood stocked ones had no problem.

Both non-wood stock material types change dimensionally and structurally with temperature.

All stock fore end's bend from external pressure some amount relative to the axis of a receiver solidly fixed to them. It's the most at the fore end's tip and much less close to the receiver and it depends on the size and material, too. The axis and amount of that pressure depends on how the stock's held and steadied by the shooter. If you measure how much they do bend, you may well be surprised. There's no way any pressure point from the fore end to the barrel will remain constant in amount and axis across all shooting positions. In some postions, it varies more than others. And that variable gets transferred to the barrel so it's not going to behave the same across all positions.

So do you think a 30 caliber, 26" thick, heavy target weight 4.4 pound barrel's stiffer than a 30 caliber, 22" thin, featherweight 2.1 pound sporter barrel and the feather weight one should have a pressure pad on it from the fore end?
 
Last edited:
Bart,

Yes I agree that putting pressure
on the forearm at different locations
will affect the pressure on the barrel
at the point where it is glass bedded
thus an inconsistency is introduced.
Likewise putting pressure on the
forearm at different locations will
affect the pressure at the point
where where the stock is secured
to the action. This pressure is actually
torque caused by a force applied to
a moment arm. There is actually
more torque on an action when a
barrel is completely floated. It is well
known that glass bedding the barrel
a few inches in front of the lug greatly
improves accuracy. If you have a
heavy 1.25 inch barrel with a straight
contour and it is 33 inches long you
have some major weight to support, in
such a case I would also recommend
glass bedding a few inches at the far
end of the forearm. If done correctly
these contact spots will transfer the
energy from the shock wave into the
stock. So the bottom line is that free
floating a barrel does not alleviate
the problem which occurs when
pressure is applied to the forearm
at different locations.

splatman
 
The most accurate, match winning, record setting, receiver bedded rifles in all disciplines have nothing touching their barrels except the receiver. Their owners have oft times proved to others that bedding under the barrel causes vertical shot stringing. But if you and your stuff isn't up to the precision to show it, then you'll never understand.

If you shoot your barrel-bedded stuff into no worse than 1 inch at 300, 3 inches at 600 or 6 inches at 1000 for 20 to 30 shot strings in as many minutes, then I'll be interested.
 
Last edited:
Sorry not all the top shooters float
their barrels. I don't think you
understand... its not whether you
float your barrel or not. Its all
about consistency in managing
your rifle and your loads.
splatman
 
Sierra uses one of these to test their bullets

http://www.benchrest.com/magnummetal/

Barrel sure not free floated

In order to accomplish accuracy firing tests, Sierra utilizes our 300- meter underground testing range daily. 200-yard accuracy evaluations are conducted on rifle bullets using a precision unrestricted machine rest. We also conduct daily 50-yard accuracy evaluations on our pistol bullets using a specially designed machine rest.
 
The action is free floated. You gotta float something. It's used for just testing bullets for quality for Sierra Bullets.

Sierra's earlier rail guns were a simpler design with fewer parts. They used Savage actions earlier and Remington ones before them.

Some folks in the late '60's epoxied a 6" long near 2" square split aluminum block in wood stock fore ends clamped on match rifle barrels with the action and box magazine floating in the stock. Accuracy with .308 Win barrels was no better than conventional epoxy bedding receivers with the barrels free floating.
 
Last edited:
True, but a barrel block also produces no worse accuracy than traditional epoxy bedding, and is easier to do if you have a machine shop to build the block.

The biggest advantage of a barrel block is that you can get away with using heavier barrels than the receiver was ever designed to support, because the receiver only has to support its own mass as the barrel is supported by the block. You see this fairly frequently with Ruger 10/22s that have been tricked out with a large bull barrel and unlimited class benchresters.

Jimro
 
In gunsmithing school in the 70s we were taught to completely bed the receiver + 2" of the barrel .This for typical hunting rifles at least.
My last gun purchase was a Kimber syn/SS supposed to be free floating but wasn't .I made it free floating which dropped the groups in half ! I'll take it !

Vibration and their problems can be frustrating .A few [non-gun] problems I've dealt with defied all logic and reason! :eek:

Bart , it's spelled 'metallurgy ' :)
 
mete, I know how it's spelled. Sometimes my fingers don't double tap a key when they should.

And it's my opinion that several myths about firearms have been passed on to 'smith students be well meaning teachers who are ignorant of realities and ignore the facts that counter their beliefs.
 
Last edited:
In gunsmithing school in the 70s we were taught to completely bed the receiver + 2" of the barrel .This for typical hunting rifles at least.
My last gun purchase was a Kimber syn/SS supposed to be free floating but wasn't .I made it free floating which dropped the groups in half ! I'll take it !
Click to expand...

Mete, you learned on an M98 action?

Jimro
 
You must log in or register to reply here.
Back
Top