How many sheets of printer paper between floated barrel and stock?

[ChrisBCS]

...to keep the stock from contacting when the barrel heats and "walks around" (as I've read it anecdotally put)?

 

[Qualicum]

0?

 

[bjay]

Dollar bill...is good enough

 

[Cordova13]

If you have a stock that has flex in it then maybe use a little bigger gap

 

[DirtMerchant]

^ if you've got a stock that flexes that much, you should replace the stock

 

[david8989]

a dollar bill is the standard measurement

 

[TOP PREDATOR]

depends on how thick the paper is

dollar bill is good, a benjamin is even better if taking pictures.

i personally would rather have the gap of a quarter if on a flexy (or for that matter any) stock, silver dollar if taking pictures.

just realized even "air space" costs in this sport

 

[DirtMerchant]

The rifle don't care how much space there is between the stock and barrel,...
Take a look at the air space between yer floatin' rail and the barrel on an AR,..
The main thing is you don't want the stock touching the barrel.

 

[Bill Larson]

Floating the barrel is not an end to all accuracy problems..on lite barrels stock pressure is a good thing....??

 

[LRShooter101]

IMHO, the old "Dollar Bill Test" is some wonderful "Urban Legend" stuff.

Multiple issues that come into play here, so contrary to popular belief there is no short simple answer.

Barrel Profile - will have a lot to do with how your barrel behaves, and you can't just use a blanket statement to cover all of them. Per above, some thinner profile barrels are intentionally setup with pressure/tension on them to improve performance. Medium profile barrels may need some substantial free floating. Heavier profile barrels may do just fine with the dollar bill clearance.

Barrel Whip - this is more of an issue the lighter the profile, though just about every barrel will actually whip to some degree. Per above, to combat this some thinner profile barrels are actually supported to reduce or control this issue. Medium profile barrels may actually require some substantial clearance so that they can whip without making any stock contact. Heavier profile barrels may not whip enough to have any interaction with the stock.

Barrel Walk - depending on a number of factors (profile, stress, heating, etc) a barrel may shift or move, and once again a stock may be designed to try and control or limit this, or the stock may be floated enough to not allow any contact.

Personally, I run a stock with enough clearance that there is no possible way for the barrel and stock to contact/interact with each other.

This subject is misunderstood, and IMHO needs a lot more research and education.

The video below brings up a lot of questions:
https://www.youtube.com/watch?v=KZvRIVorJAI
You have a barreled action duct taped by the barrel to a "2x4 stock". Needless to say this flies in the face of things like free floating the barrel and bedding the receiver. This barreled action uses a Teludyne Barrel which is supposed to eliminate any issues like whipping or walking of the barrel.

 

[DirtMerchant]

There's a whole lotta of redneck in me that'd say "Hail yes!" if asked "do yah wanna shoot it?"

Lets take a look at the system,.. It's a tensioned system not unlike many battle rifles pre-civil war thru Korean and Vietnam. Mosin Nagant, K93, Springfield '03, Garand, Lee Enfield,...

If you break down precision shooting into a series of equations we end up with a crapton of variables. Some we can control, the rifle system, body posture, ammunition, many we can't environmentals,...
However we can predict the outcome,...

If I can torque the stock on my precision rifle to point I make contact with the barrel, I have now added another variable to the equation and it will affect the accuracy of the shot.

The redneck tensioned system made of a 2x4 & duct tape is going to become less stable over a series of firings, the accuracy will degrade.

back to the original question: As LRS stated there is no simple answer, some of it's personal preference and some practical. The air gap of the stock to barrel on my rifle is a bit over 1/16"

 

[LRShooter101]

. . . SNIP . . .

The redneck tensioned system made of a 2x4 & duct tape is going to become less stable over a series of firings, the accuracy will degrade.

. . . SNIP . . .

Not sure that you are up to speed on the Teludyne Straight Jacket Barrel System?
StraightJacket Barrel System guarantees sub-MOA accuracy, MoszillaTeludyne | Game-Changing Barrel Technologies
It is a lot more than a rifle barrel, and as such, this setup is a lot more than a rifle duct taped to a 2x4.

You can also look at things like Barrel Block technology:
https://www.google.com/search?q=barrel+block+rifle&espv=2&source=lnms&tbm=isch&sa=X&ei=Wx4CVLjCL87oggTxw4GQDw&sqi=2&ved=0CAYQ_AUoAQ&biw=993&bih=446

Barrel Block on Savage-Action F-TR Rig within AccurateShooter.com

Both of these concepts make you question many of the traditional accepted practices. Teludyne addresses things like barrel harmonics & heating, and the Barrel Block systems addresses things like the barreled action and stock interface.

Sorry for the sidetrack, but there is a lot more that goes into how all of the components of a "rifle system" go together and interact. Some research is being done, and we are understanding more, but IMHO the world of Precision Long Range Rifle shooting still has to many urban legends that are accepted as scientific fact.

 

[DirtMerchant]

Not sure that you are up to speed on the Teludyne Straight Jacket Barrel System?

Actually I did do some research on the Teludyne there was some interesting stuff.

I found this article/review from 2012

The StraightJacket Barrel System - Shooting Reviews

I also followed a number of the links in the article, one of the links was a review where the system was shot to failure. From the sounds of the after effects they're using some type of fluid jacketing to draw heat away from the barrel and chamber. Sounds like this jacket has some vibration damping qualities as well.
Cost effective?

Actually as systems go I'm liking the tube gun chassis,...

LRS - not lookin' to start a pissin' contest

 

[LRShooter101]

Not looking to start a pissin contest either, just looking to stimulate some discussion on the topic.

Different strokes for different folks, and different ways to achieve goals. In this case the question is, how many shooters really understand the goal and what it really takes to get there?

I have watched plenty of people sliding a dollar bill between a rifle barrel and stock, thinking that if they had that clearance, then everything was guaranteed to be good to go, when that is not necessarily the case. How many of them really understand barrel behavior (harmonics, whip, heating, etc), how many of them really understand the interactions of the various components (barrel, receiver, stock, etc), how many of them really understand what actually goes into producing results?

I hope that more "brains" will push the knowledge base, more shooters will learn from them, and that overall the shooting sports will move forward!

It kills me when I still see shooters showing up for one of my precision long range shooting classes with a rifle, ammo, optics, etc that are all based on outdated technology, theory, and knowledge. I then usually end up spending hours trying to debunk all of the "urban legends" that are thrown around all over forums like this as if they were hard well proven scientific fact.

Back to the original topic, what is the real hard science that says that if you can slide a dollar bill between a barrel and stock that you are good?

 

[DirtMerchant]

Back to the original topic, what is the real hard science that says that if you can slide a dollar bill between a barrel and stock that you are good?

None that I'm aware of,...

 

[SOC308]

You know what's funny is I had the owner of Teludyne on the range one day in summer of 2012, and the only rifle of his that would shoot worth a damn was his personal rifle, which he professed started off w/ a Bartlein Barrel in a McMillan A5 w/ a Zeiss scope... He provided a straight jacketed barrel to a friend of mine on his ruger 308 hunting rifle... We all shot it, the best group they could get it to print with MANY different types of match grade ammo was 1.5-2 inches at 100 yards. I invited the guy out to our sniper golf shooting competitions and nary heard a word back from him. My buddy is a sponsored shooter and he's since shooting a teludyne barreled POF, but it shoots just like my POF and just weighs more. I don't see the benefits.... Sure I can take a 2'' straight barreled action, strap it to a 2x4, and it'll probably shoot too. Its great technology, but all the claims they make.... please

To the original question... there is no magic about being able to slide a dollar bill under your barrel and it'll automatically decrease the size of your groups. what it does is remove a variable from the equation and makes it easier for us to find a reasonable solution to the problem. if you're constantly putting varying pressure into a system how do you account for it in your equation? By simply taking it out of the equation you are removing the likelihood of it interfering with your results.

 

[LRShooter101]

Teludyne - to clarify, I am NOT singing their praises! I do not own one, and based on the research that I have done, I can't say one way or another if the claims they make are well substantiated. I posted the reference to them because they came into the conversation via the "Rifles Only 2x4 Demo", which flies in the face of many hardcore precision rifle urban legends such as you must have a rifle with a bedded stock and free floated barrel for any level of accuracy. I also mentioned them, because they have not accepted the standard practices of age old barrel design, but instead have tried to address many of the issues that are known to impact accuracy. Whether they have done that 100% successfully at this point, I am not 100% sure, though I can agree with their theories/methodologies.

Dollar Bill Gap / Free Floated Barrel - not allowing the stock and barrel to make contact, can remove a variable from the equation of trying to make any rifle shoot consistently & accurately. That being said, not all barrel profiles are stiff enough, not all stock designs are stiff enough, and not all stock & receiver mounting options are tight enough, to prevent the barrel and stock from contacting one another with a gap that is only the thickness of a sheet of paper. If one of those situations exists, nothing has really been accomplished (variable has not been removed) by being able to slide the dollar bill between the barrel and stock.

EDIT - go on Youtube and do a search for Barrel Whip or Barrel Flex, and I think that it will amaze most people how much a barrel can actually move during firing:
https://www.youtube.com/watch?v=cpTzr4yZvtc

https://www.youtube.com/watch?v=BgD6MtSBfzM

https://www.youtube.com/watch?v=_9ULBtsnkR0

There are plenty more to look at.

Once you see and understand that this amount of movement can exists, then you can appreciate why a gap the size of a sheet of paper may have no significance. Obviously the amount of whip/movement that exists depends on a number of factors, and for some designs, that gap may be all that is needed.

Per my comments above, you have to look at the "full big picture", take everything into account, and determine what really impacts consistency & accuracy in your particular setup?

 

[damoncali]

Any movement from heat is going to be way less than the movement from vibration/recoil. A dollar bill isn't enough to prevent contact, and it's not a given that contact is bad. We float barrels so we know what we're getting - no contact. If there is contact, and it changes, it throws another variable in. But having something touch the barrel is not automatically going to make it shoot worse. It might actually shoot better.

 

[M40_A1]

How many sheets of printer paper between floated barrel and stock?

for a field bolt rifle, however many sheets make up about 1/8" works for me.

 

[NV Ranger]

Usually right around a half a ream "borrowed" from the office ensures a proper free float.

 

[Forgetful Coyote]

Varmint Al's Fluted Barrel Stiffness Analysis

See here to watch the myriad of ways barrels twist and turn during firing. Obviously the proportions are multiplied a huge amount for visual purposes; with a big ole HV benchrest barrel, most of these movements will not be detectable by the human eye, or if any then it will be very small amounts. Varmint Al does a great job with his modelling, but the conjecture and "his own ideas" are stuff Id take with a grain of salt.

"Rifle Accuracy Facts" by Vaughn is the be-all, end-all sources of everything mechanical/technical about rifle accuracy. Varmint Als modelling shows a lot of what Vaughn talked about.

Far as the Teludyne system, dont waste the money. See Joel Pendergraft`s former record rifle:

Joel Pendergraft Sets New IBS 1000-Yard Heavy Gun World Record « Daily Bulletin

Dave Tooley experimented with compression barrels at one point in time. From what I know they shot well.

Tensioned barrels have been well known for a while in BR.

1000yd Heavy Gun competitors have experimented with most everything under the sun. Sleeve with tension, sleeve with compression, sleeve with neither, tensioned sleeve with water cooling, etc and they all shot essentially round groups.

Its been boiled down to a pretty basic formula after all this experimentation, the most accurate rifle will be a rail gun in SR BR and a Heavy Gun(usually) will be the most accurate in LR BR - likely because rail guns aint allowed. Yes I know a light gun holds the record for 10 shot 1000yd group. Just talk to someone like Bill Shehane who has experimented with all manner of accuracy contraptions. More often than not, the most accurate rifle we can currently come up with is a 1.25" to 1.45" barrel(no need to go bigger, tuning becomes a bit more difficult much bigger than those, or should I say you stop seeing advantages past 1.25" straight cylinder contour) either free-floated or set in a barrel-block that is usually mounted quite close to the action. All these methods and devices are reaching for the same goal, tuning the barrel. Barrel blocks are preferred when allowed because one can easily fine-tune the barrel by moving the barrel forward/backward in the block a bit.

In LV/HV short range BR, the same thing is trying to be accomplished by every competitor: tuning the barrel to what it likes best. However, they dont have a high enough weight limit to use barrel blocks(unless you get creative ala Speedy Gonzalez`s "Bedding Isolation System": New stuff we are playing with in the F-Class game

One that I plan to pick up soon is Tony Boyer`s book(the king of short range benchrest so to speak). The best practical method for an accurate rifle one can come to is a fully free-floated barrel, with the action glued into the stock. Thats how its done in short range BR. If you want to stick with one load, like rimfire guys have to, a good idea would be a barrel tuner, which allows one to tune the barrel to the load, instead of the other way around.






Please correct me in any of this if you feel Im missing the target so-to-speak.