Barrel free-float -> vs. -> barrel block mounting

[hemiford]

Free floating the barrel usually makes a rifle more accurate, this is
commonly accepted wisdom, and it works !

When you do this, the weight of the entire barrel is cantilevered
off of the end of the action.

At some point, no, this is a gray area not a point, as the barrel
gets longer and/or heavier, the cantilever effect surely begins to
distort the action by bending the end of it downward.
This cannot be good.

So my question is: What are your experiences & suspicions as to
how heavy a barrel can be reliably free floated ?

( I know this will depend on the individual action, some designs
are indeed inherently more rigid than others. )

 

[Rich Coyle]

I used to have a 'smith who would bed 3/4" of the barrel next to the action. How would this affect the action?

 

[MudRunner2005]

I used to have a 'smith who would bed 3/4" of the barrel next to the action. How would this affect the action?

My smith usually beds the whole action footprint, the lug, and also about 1.5" in front of the lug (enough to support the barrel shank), and floats the rest of the barrel. Don't know how much that affects the accuracy, compared to the blueprinting, but whatever he's doing, it works.

 

[FearNoWind]

The weight of the barrel would have to bend the recoil lug before could affect the action. With the recoil lug solidly bedded into the stock it can't bend. Clamp a recoil lug into a suitable vise and test the amount of pressure it takes to bend one.
I wouldn't worry about it ......
\

 

[Joel Russo]

I have not experienced any issues with bedding a few inches of the heavy barreled, large caliber rifles that do not use a barrel block. In fact, I have shot consistently small groups at extremely long ranges with a few personal rifles.
Here's how I bed them. This is an 1.450" dia action with an 1.450" barrel shank that tapers to 1.350" at 30".

 

[4xforfun]

I have not experienced any issues with bedding a few inches of the heavy barreled, large caliber rifles that do not use a barrel block. In fact, I have shot consistently small groups at extremely long ranges with a few personal rifles.
Here's how I bed them. This is an 1.450" dia action with an 1.450" barrel shank that tapers to 1.350" at 30".

Looks like the bedding area in your pictures is definately NOT a Rem 700 foot print, so I agree with you.....shouldn't be a problem. The biggest BBL I have a a Rem action is a 30+ inch Rem Varment coutour. All of my heavier tubes are on BAT actions, including 1.45 x 30"+ straight taper on a 10"x 2" BAT "L".

I can't imagin screwing a 1.45 straight on any rem or Rem Clone. I think that there is a limit an action can accuratly take.

Just my .02.

Tod

 

[billm67]

For a long time the practice of bedding an action included bedding the barrel channel. I also had several Remingtons where there was a knob of walnut in the barrel channel that was a pressure point. They were put in on purpose thinking that it improved accuracy. As soon as the barrel heated up you started to have vertical stringing. Free floating came out of those older stocks and pressure points. I have seen stocks that were very stiff (think 90's Remington Varmint specials with the laminated stocks) where the barrel channel was bedded out the entire barrel channel and they shot very well. As long as there are no pressure points and the stock doesn't flex it works well. With all of the new composite stocks...they have a slight amount of flex. But you should be able to bed the first inch and a half or so in front of the recoil lug and free float the rest of the barrel. However if you have a heavy enough barrel it will still flex the receiver. But instead of it being at the recoil lug it is pushed back onto the tang.

 

[Deleted member 46119]

Simple - bed it/float it how it shoots best.
Complicated - knowing how it will shoot best before deciding how to bed it/float it.

LOL

I have a Barrel Block rifle and of course many conventional.

I've been reading about bedding and floating for 40 years. Doing it for only 5ish. It was all theory until I started doing it.

These are my observations and beliefs. If you don't agree, explain why. Failure to explain is not helpful to anyone's understanding making you a TOAD.

Engineering: Something to remember, every weight and torque on an action will distort it. How much? It would take some very sophisticated equipment to measure. Does this distortion have and effect on accuracy? Of course but how much? Yes, taking an action screw out will distort it. Putting it in will distort it. Mounting a scope will distort it. Removing the scope will distort it. Blah, blah, blah. Putting your finger on it will distort it. It it measurable? Does it impact accuracy?

The purpose of bedding is to stabilized the distortion and make it repeatable. Bedding some or all of the barrel is intended to support/reduce some of the responsibility of the action to support the weight of the barrel and transfer that to the stock. Reducing/stabilizing distortion of the action.

The purpose of free floating is to reduce/stabilize/remove distortions on the barrel from the stock. If it's a wood stock, changes in humidity cause the stock to distort. If the barrel is touching the stock, the distortion on the action and barrel will change from shot to shot. All stock materials will distort with temperature changes, causing the action/barrel contact to distort. Same shot to shot, bad. Plastic fantastic stocks flex/distort because, because what? Because they are plastic. Not very rigid stuff. Not very temperature stable stuff. Blah, blah. You can free float a plastic stock but man what a battle. I have had some success floating and bedding plastics. A tiny amount of weight on the stock say from your thumb pressing on the stock behind the tang will change the distortion of the stock taking the action with it. How much? In this case it doesn't take sophisticated equipment to measure. Enough to mess up shots, even if bedded and floated. Switching the same rifle to Laminated Wood stock, bedded and floated = less flexing = less distortion = better repeatability (accuracy).

The purpose of Barrel Block is to change/stabilize/reduce distortion of the action and barrel by taking the responsibility of supporting the barrel away from the action. A reminder, of course, the barrel is cantilevered off the action which means the the action and barrel will be distorted from the weight. The Barrel block reduces that. The action hangs off the barrel. The portion of the barrel forward of the block is the only part of the barrel that is cantilevered. It will bend at this point. How much? It would take some very sophisticated equipment to measure.

NOTE: There is one rifle I saw on AccurateShooter.com that uses magnets to push up on the end of the barrel. Reducing the weight carried by the action. I find this a very intriguing concept. It would take some pretty complicated setup to measure the effect, though not anywhere as sophisticated as without the magnet system. A reference plate (granite block) a height gauge. Some time. Hmm..

Then there is the flexing moment difference between action supported and barrel block supported barrel.... Oh wait, that is a different subject.... Some other time then....

 

[Deleted member 46119]

Oh, yeah. Just to be pedantic.

The change in spring pressure as rounds are fed from a magazine will, you guessed it, distort the action. How much.......

Think about it when you can't repeat a group that you did single feed with all things the same but fed from the magazine.

 

[Deleted member 46119]

I just can't leave well enough alone.

If all the "standard" ways a rifle is shipped cause so much distortion, why haven't manufactures changed it in the last 100+ years.

KISS.

Ruger with the RPR, changed it. It will take me a bit to come up with the wording how to compare it to bedding/floading and barrel blocks. I believe I will have to disassemble my forend first or maybe the whole rifle so I can see the load points. Then I can describe it.

Eliso (sp?) and "tube gun" makers are "custom" and not in the KISS realm.

 

[waltercrouse]

Simple - bed it/float it how it shoots best.
Complicated - knowing how it will shoot best before deciding how to bed it/float it.

LOL

I have a Barrel Block rifle and of course many conventional.

I've been reading about bedding and floating for 40 years. Doing it for only 5ish. It was all theory until I started doing it.

These are my observations and beliefs. If you don't agree, explain why. Failure to explain is not helpful to anyone's understanding making you a TOAD.

Engineering: Something to remember, every weight and torque on an action will distort it. How much? It would take some very sophisticated equipment to measure. Does this distortion have and effect on accuracy? Of course but how much? Yes, taking an action screw out will distort it. Putting it in will distort it. Mounting a scope will distort it. Removing the scope will distort it. Blah, blah, blah. Putting your finger on it will distort it. It it measurable? Does it impact accuracy?

The purpose of bedding is to stabilized the distortion and make it repeatable. Bedding some or all of the barrel is intended to support/reduce some of the responsibility of the action to support the weight of the barrel and transfer that to the stock. Reducing/stabilizing distortion of the action.

The purpose of free floating is to reduce/stabilize/remove distortions on the barrel from the stock. If it's a wood stock, changes in humidity cause the stock to distort. If the barrel is touching the stock, the distortion on the action and barrel will change from shot to shot. All stock materials will distort with temperature changes, causing the action/barrel contact to distort. Same shot to shot, bad. Plastic fantastic stocks flex/distort because, because what? Because they are plastic. Not very rigid stuff. Not very temperature stable stuff. Blah, blah. You can free float a plastic stock but man what a battle. I have had some success floating and bedding plastics. A tiny amount of weight on the stock say from your thumb pressing on the stock behind the tang will change the distortion of the stock taking the action with it. How much? In this case it doesn't take sophisticated equipment to measure. Enough to mess up shots, even if bedded and floated. Switching the same rifle to Laminated Wood stock, bedded and floated = less flexing = less distortion = better repeatability (accuracy).

The purpose of Barrel Block is to change/stabilize/reduce distortion of the action and barrel by taking the responsibility of supporting the barrel away from the action. A reminder, of course, the barrel is cantilevered off the action which means the the action and barrel will be distorted from the weight. The Barrel block reduces that. The action hangs off the barrel. The portion of the barrel forward of the block is the only part of the barrel that is cantilevered. It will bend at this point. How much? It would take some very sophisticated equipment to measure.

NOTE: There is one rifle I saw on AccurateShooter.com that uses magnets to push up on the end of the barrel. Reducing the weight carried by the action. I find this a very intriguing concept. It would take some pretty complicated setup to measure the effect, though not anywhere as sophisticated as without the magnet system. A reference plate (granite block) a height gauge. Some time. Hmm..

Then there is the flexing moment difference between action supported and barrel block supported barrel.... Oh wait, that is a different subject.... Some other time then....

I believe in the 3/4 bedding of the stock. Your barrel has harmonics ,meaning that it resinates ,each load light or heavy changes the harmonic . By supporting the barrel you reduce the amount harmonic (barrel whip). The heavier barrel the less barrel whip and lighter the barrel the more barrel whip. Meaning the lighter barrel the more area needs bedding. gun)

 

[MudRunner2005]

I believe in the 3/4 bedding of the stock. Your barrel has harmonics ,meaning that it resinates ,each load light or heavy changes the harmonic . By supporting the barrel you reduce the amount harmonic (barrel whip). The heavier barrel the less barrel whip and lighter the barrel the more barrel whip. Meaning the lighter barrel the more area needs bedding. gun)

I see what you're saying, but the fact is, the barrel will still distort, and still be susceptible to harmonics... It will just deflect in a different direction that has no pressure on it. Just like electricity, it will follow the path of least resistance.

Unless that barrel is bedded and firmly held in place 360-degrees around it the entire length, it will always be susceptible to harmonics in one way or another. That's partly why carbon-wrapped barrels are so popular, other than their weight-reducing properties. You get the stiffness and rigidity of a solid piece of stock, that is less susceptible to harmonics, but out of a barrel that weighs considerably less.

 

[Deleted member 46119]

Putting together all the aspects of action and barrel distortion in one small package with the added contributions about barrel whip has got me thinking about how much the barrel droops.

We can all understand how barrel droop would contribute to whip. Just use the garden hose. Support the end of the hose a foot or so back from the tip. Turn on the water and the hose will rise.

Of course floating the barrel is used to allow the whip to be as consistent as possible.

So the question is: can we reduce and make even more consistent, barrel whip?

Well of course. Bench rest shooters do it with thicker barrels. This also counters heat based distortion but that's another challenge.

What else can we do?

Back to the magnets idea... Thinking... Good?

 

[hemiford]

Well thank you Gentlemen. Very interesting so far.

It seems to me that there might be several angles of attack to this
goal of controlling barrel vibrations and, ultimately, making the rifle's
shots more identical.

Here's an analogy: I have built home stereo speakers and can tell you
that, if possible, you want a HEAVY cabinet that is accoustically DEAD.
No cabinet vibrations. Now, if you can somehow dampen the rifle barrel
in a similar way so it doesn't vibrate, you will increase its accuracy.
Maybe the carbon fiber wrap does this. A thicker/heavier barrel will do this.
Maybe wrapping the barrel in thick tar paper will do this. Maybe three
pounds of silly putty.
Anything to dampen vibrations.

OK, another angle of attack might be the barrel mounting, already
somewhat discussed here. I guess I can generalize by saying that
any mounting method which minimizes barrel vibrations is a good
mounting method.
This is sort of where I started the thread.

If a barrel weighs 8~~10 pounds (which by the way is part of my
evil secret plan) and the action weighs 2.5 pounds, I cannot see
grabbing the action and hanging the barrel off the end of the action.
I CAN see grabbing the barrel and hanging the action off the end
of the barrel.

The stock cannot be flexible, at all, in any case.

Working downstream, I guess I could then continue to argue that
your shoulder would be the next problem area, but at this point,
I quit the theoretical rambling.

Anyway, I started the thread to be about barrel mounting. I realize my
plan is not typical, but this barrel I'm considering will be 1.350 OD
for ten inches, then tapering to about 1.100 at 38 inches total.
Mounted on a Rem 700 clone. If I bed the full 10-in 1.350 section,
I cannot believe there is any piece of wood that would bend/distort
a 1.350 piece of steel, no matter how damp the wood gets, or what a
temperature change might do to the wood.

So, there is my current interest, but still I'm all ears about vibration
control in general, even though you might think it off-topic.