Bedding & Barrels; Total Free Float Barrels vs: Some Fore End Pressure Points

[Bart B.]

I'm curious as to folks' opinions as to what's best.

Some feel there's a need to have some bedding under the barrel in the stock's fore end putting pressure on the barrel in at least one place.

Others think nothing should touch the barrel anywhere except the receiver it's screwed into; totally free floating.

Has anyone ever measured how much a stock's fore end bends relative to an epoxy-bedded receiver axis in different shooting positions and holds such as benched, standing, sitting, prone with and without a sling? Or with the rifle held vertical with no force at right angles to the bore axis then with the rifle horizontal and its fore end tip resting on something and the toe resting on the benchtop or something else? When I did this, my jaw dropped!!!!

How many top-ranked benchresters have pressure points to their barrels from bedding pads in their stock's fore ends?

 

[Larryh128]

Some factory barrels will like the forearm contact but about every stress relieved barrel is going to shoot better free floated. I have floated some very light barrels with excellent results. The big problem with forearm pressure is that the pressure can change with the weather conditions. Wood & even composite stocks will shrink/expand with temperature changes which would give you very inconsistant pressure on the forearm which will result in impact changes.

 

[shortgrass]

The amount of fore arm pressure could be an infinate number. I think most factory rifles probably have too much. One stroke with a barrel channel tool would be less, two strokes would be even less. Most just go with free floating, either because it's what they heard or read, or it's become the excepted norm. Every rifle would be different, in my opinion. When it comes to bedding (and alot of other things concerning rifles) there's alot of variables, each of which would have an effect. No set rules,, lots of generalizations.

 

[Grimstod]

Bedding the barrel is like trying to tune the barrel with a tuner only you can't adjust it. It's really hit and miss on if it will help. Sometimes it does sometimes it's doesn't.

All the above that I have said is for people who shoot factory ammo. If you do load development then you free float all the way and you will ALWAYS get better results. A stock pressing on the mid section of a barrel if it changes presure by even an oz it will have big change on POI. I have a friend with a bull barreled gun that refuses to free float and every time the temperature changes his POI changes. He scratches his head and wonders why it happens. I try to tell him that since he is doing load development he needs to free float but he won't listen. Some people never learn. One more thing pretty much every precision gun manufacture freefloats their barrel now. Only cheap guns or older ones will have stock pressuring the barrel.

When I get my laptop to a wifi spot I will try to post the calc formula to determin barrel deflection.

 

[shortgrass]

Grimstod, a pressure point can be adjusted. All it takes is sand paper or a barrel channel tool and some sealer, if the stock is made of wood. Pressure points are intended to be placed, evenly, near the end of the forearm. A "pressure point" anywhere else in the barrel channel is just poor inletting. Heavy barrels are, generally, floated. The idea of the pressure point is to stabilize harmonics on lighter weight barrels, like sporter weight. A 'tuner' as part of the stock instead of on the barrel. Sometimes it works, sometimes not. When I took stockmaking, 20 yrs. ago when in gunsmithing school, we built wood stocked sporters from blanks, by hand. The instructor insisted on a pressure point. If it was too heavy, it could always be lightened or removed. That instructor retired 18-19 years ago, just to give an idea of his age. He had learned to make stocks as a teenager from his father. I'd call that close to two life times of experience. 'Glass' was frowned upon, a cure for sloppy craftsmanship. Today, most all want the "cure all",,,,, as fine tuning a pressure point by a real stockmaker is expensive.

 

[Macropod]

I would always free float a barrel. Even rifles that I have that originally had barrel bedding ended up being free floated... One had 'O'Connor' barrel bedding in a modern incarnation of a No.4 Enfield action - it was ripped out and the rifle is now a much better shooter than previously. ;D

Weatherby rifles are interesting in this respect. The Mk 5's often had upward pressure in the fore end yet the 30-378 Accumark I have is free-floated.

I've found it much more reliable to free float. Much more consistent, but then I reload.

 

[Grimstod]

Grimstod, a pressure point can be adjusted. All it takes is sand paper or a barrel channel tool and some sealer, if the stock is made of wood. Pressure points are intended to be placed, evenly, near the end of the forearm. A "pressure point" anywhere else in the barrel channel is just poor inletting. Heavy barrels are, generally, floated. The idea of the pressure point is to stabilize harmonics on lighter weight barrels, like sporter weight. A 'tuner' as part of the stock instead of on the barrel. Sometimes it works, sometimes not. When I took stockmaking, 20 yrs. ago when in gunsmithing school, we built wood stocked sporters from blanks, by hand. The instructor insisted on a pressure point. If it was too heavy, it could always be lightened or removed. That instructor retired 18-19 years ago, just to give an idea of his age. He had learned to make stocks as a teenager from his father. I'd call that close to two life times of experience. 'Glass' was frowned upon, a cure for sloppy craftsmanship. Today, most all want the "cure all",,,,, as fine tuning a pressure point by a real stockmaker is expensive.

I totally disagree that this is practical. You cannot adjust it without taking the gun apart. If you switch from one type of ammo that likes a certain amount of pressure to another type of ammo that likes, lets say more pressure on the barrel you can't adjust it on the fly. By contrast tuning your action screws is something that can be done without taking your gun apart and does not require you to add material to the stock to increase presser or to sand material away to remove it and lessen pressure. You should read about tuners and how they affect your groups and ammo selection here.
http://www.accuratereloading.com/hoen4000.html
and here for tuning the action
http://bulletin.accurateshooter.com/2012/12/tuning-savage-actions-using-action-screw-torque-settings/


Now for your retired gun stock maker he is old school. This is the 21st century. Not the 20th. Gun smithing and gun technology has come a long way since then. I used to be a believer in pressure points but now I am not because I did my research and the math. It is only good for factory ammo and it needs to be adjustable. Letting the wood(plastic) touch the barrel is not adjustable. If you want to do harmonic tuning with your stock then put a bolt under the barrel in your stock and tighten it like on this rimfire stock that has a built in tuner that applies pressure to the action. http://www.accurateshooter.com/stocks/rimfire-stock-with-built-in-tuner/
There is also a manufacturer called Archangel that makes a stock for mosins that has a tuner in it that allows you to put pressure on the barrel at the end of the stock much like your friend did but it is adjustable with an allen wrench.

As for how much it affect POI here is the formula to determine just how much the end of your barrel will move when you press on it. A .001 or even a .0001th of an inch will have a big change in POI down range.

Y= maximum deflection at free end in inches
P= load exerted at the end of the barrel. Us pounds
L= length of barrel in inches
r sub o= outside diameter radius
r sub i= inside diameter radius of boar
E= modulus of elasticity. Use 414 for steel and 410 for stainless steel. There are more numbers out there for other types of steel but these will get you close.


In conclusion just free float the barrel and do load development. If you shoot factory ammo and want accuracy for competitions then your asking for the most part, the imposable.

 

[shortgrass]

yep! I'm old school , too. Still make at least one stock every year from a blank by hand. Light barreled huntin' rifles. Not everything revolves around the "machining". Which, by the way, I've spent since '74, and has made me a decent living. Wasn't hard to find a machine shop in 'need' of some part time, experienced help while I was in school. I'm not much of a "button pusher", but I don't need a set-up man and I don't need a programer for the ones & twos that come through the shop, either. My main work, today , is making the jigs/fixtures and tooling selection for the 'line'. I'm the "tool" guy/trouble shooter. My hunting rifles only get "one load". It's not practical to have half a dozen when one is all thats really needed. Components, you say? When I find the "one " I like, I lay in a supply. I haven't wanted for a thing with the current components crunch. Craftsmanship and and hand work still matter to some people. They tend to pay much better than the younger guys do, anyway. Quality, not quantitiy. Don't confuse a "competition rifle" with a "hunting rifle". A hunting rile is ment to be carried at 5000 ft. without being a 16+ lb. 'burden'. It needs to be able to put 3 shots in the 'kill zone' at the distance the hunter is capable of. Many times a 'tuned' pressure point is what's needed under that #2 contour barrel. But, do it any way you'd like.

 

[Bart B.]

'Tis my opinion that there's no way a pressure point on a barrel from something on the stock's fore end will remain constant in direction and amount across all ways the rifle's held and fired.

As it's very easy to see exactly how much both thick and flimsy fore ends bend in different shooting positions, it stands to reason that whatever external forces there are on the fore end will transfer directly to the barrel.

Accuracy, in my opinion, is the reduction of all variables to as close to zero as possible. The only way I know of that ensures constant and repeatable barrel position relative to the line of sight is totally free floating it with enough clearance to the fore end that in extreme conditions, the barrel still touches nothing but the receiver.

Barrels whip and wiggle exactly the same way for every shot as long as nothing interferes with them. A pressure point on them is interference and there's no way it will remain constant. Remington tried adjustable pressure points 90 degrees apart angling 45 degrees up from the fore end tip to the barrel on their 40X 22 rimfire match rifles. While the idea impressed 95% of the competitors, the remaining 5% shooting the best scores proved those things hurt accuracy. While they sometimes improved accuracy from benched rifles with poor bedding around their receivers, zeros on the sights were not consistant across different shooting postions. And unless the screws were "clicked" to some amount from just barely touching the barrel while in a given shooting position, in another position they had different pressures because of external forces on the stock not being the same.

In contrast, Winchester 52 rimfire rifles originally had a barrel band holding the barrel to the stock's fore end tip. After complaints from competitors who got better accuracy with that band removed and totally free floating those heavy barrels, Winchester did the same thing and totally free floated their barrels.

Measure how much a stock's fore end bends relative to the receiver's axis across all sorts of positions. It's an eye-opener for most folks.

And 22" long 30 caliber featherweight hunting barrels are usually just as stiff as 26" long 30 caliber medium weight target barrels. Both have the same resonant frequency and harmonics thereof as they whip and wiggle when fired. I don't quite understand the reasoning that the lighter one would benefit from a pressure point and the heavy one would not.

 

[oldroper]

yep! I'm old school , too. Still make at least one stock every year from a blank by hand. Light barreled huntin' rifles. Not everything revolves around the "machining". Which, by the way, I've spent since '74, and has made me a decent living. Wasn't hard to find a machine shop in 'need' of some part time, experienced help while I was in school. I'm not much of a "button pusher", but I don't need a set-up man and I don't need a programer for the ones & twos that come through the shop, either. My main work, today , is making the jigs/fixtures and tooling selection for the 'line'. I'm the "tool" guy/trouble shooter. My hunting rifles only get "one load". It's not practical to have half a dozen when one is all thats really needed. Components, you say? When I find the "one " I like, I lay in a supply. I haven't wanted for a thing with the current components crunch. Craftsmanship and and hand work still matter to some people. They tend to pay much better than the younger guys do, anyway. Quality, not quantitiy. Don't confuse a "competition rifle" with a "hunting rifle". A hunting rile is ment to be carried at 5000 ft. without being a 16+ lb. 'burden'. It needs to be able to put 3 shots in the 'kill zone' at the distance the hunter is capable of. Many times a 'tuned' pressure point is what's needed under that #2 contour barrel. But, do it any way you'd like.

You are right when I shot BR we glued our action in and rail guns action/barrel was clamp in.

My hunting rifles I have bedded forward of the recoil lug and could care less about 10/15/20 shot groups and lot depends on who's barrel,contour/stock. I put same effort (money) into that build as I would a BR rifle.

I spend more time /money on a hunting rifle then I did on BR rifle because first shot is what counts and has to do with hunting ethic vs shooting paper.

 

[Bart B.]

oldroper, what if a match was fired and no sighters were allowed? All 10 or 20 shots in a string of fire were done with a cold barrel and every shot fired counted.

Would not folks shooting them also be concerned about where that first shot from a cold barrel went as well as all the subsequent ones? Especially if some of the 10-shot strings are shot in 60 seconds instead of about one minute apart like the others.

And the thing they're trying to put all their bullets into is often smaller than the "kill" zone on big game

 

[oldroper]

oldroper, what if a match was fired and no sighters were allowed? All 10 or 20 shots in a string of fire were done with a cold barrel and every shot fired counted.

Would not folks shooting them also be concerned about where that first shot from a cold barrel went as well as all the subsequent ones? Especially if some of the 10-shot strings are shot in 60 seconds instead of about one minute apart like the others.

And the thing they're trying to put all their bullets into is often smaller than the "kill" zone on big game

Bart, I haven't seen rules that require sighters to be fired at a match and far as I know that shooter's choice.

 

[Bart B.]

For NRA high power matches, sometimes sighters are stipulated in the program and may or may not be fired depending on the match program. In a lot of team matches, no sighters are allowed except in long range matches. In long range matches when a cease fire is in effect, if the delay is long enough, shooters may take another sighting shot before shooting scoring ones. And in many CMP individual and team matches, no sighters are allowed.

Info on sighters is in:

http://compete.nra.org/documents/pdf/compete/RuleBooks/HPR/hpr-book.pdf

 

[oldroper]

For NRA high power matches, sometimes sighters are stipulated in the program and may or may not be fired depending on the match program. In a lot of team matches, no sighters are allowed except in long range matches. In long range matches when a cease fire is in effect, if the delay is long enough, shooters may take another sighting shot before shooting scoring ones. And in many CMP individual and team matches, no sighters are allowed.

Info on sighters is in:

http://compete.nra.org/documents/pdf/compete/RuleBooks/HPR/hpr-book.pdf

To save time tell me what section refer to sighter and match programs in your prior post which I post below


"what if a match was fired and no sighters were allowed? All 10 or 20 shots in a string of fire were done with a cold barrel and every shot fired counted. Would not folks shooting them also be concerned about where that first shot from a cold barrel went as well as all the subsequent ones? Especially if some of the 10-shot strings are shot in 60 seconds instead of about one minute apart like the others."

 

[Bart B.]

After downloading the rules, search the document for "sighting shots" and they'll be found. That's the quickest way. Acrobat Reader has its own search function.