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BARREL BEDDING / TABOO? |
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hot30
Optics Journeyman Joined: December/27/2006 Status: Offline Points: 378 |
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Posted: August/11/2007 at 14:53 |
Have another itch to scratch. Shooting my bull barrel 7WSM the other day I noticed the " barrel sag" thing was going on. The problem is amplified due to the action being a clip loader. This type of repeater will almost always have "alot" of metal removed from the under side of the action. This leaves the receiver quite flexable. Now the "taboo" part. For accuracy its always been known that the floated barrel is the way to go. Now there is a few exceptions to this rule out there. Some that suffer this problem will resort to "barrel blocks" or bedding 6" of the barrel for support to overcome the weight of the barrel. I choose to bed the first 6" of the barrel forward of the recoil lug. Now, my barrel is 1.120 from front to rear in diameter. There is a "sweet" spot somewhere along the length of this barrel which I probably wont find, so I will bed the first 6" and see about accuracy after. The diameter in my opinion, should leave this barrel "less sensitive" to natural frequencies that occurr when fireing,but if problems arise I would slightly add to the lenght of the bedding and if this didnt give better results in accuracy I would begin to remove slight amounts of bedding until the problem was corrected.
So tell me if you might have other solutions, maybe mine is way off.? |
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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hot30, What you're describing is the exact same principle that the Browning Boss and other barrel tuners work. By changing the length of bedding against the barrel, you're changing the unsupported length to find a tuning "node." Unfortunately, this is a very "hit or miss" bedding method, and it's hard to get it right and find the absolute "sweet spot" without a lot of adding and removing bedding. It is for this reason that I don't mess with barrel bedding; results are just too inconsistent. I personally bed the action only and maybe the first inch or two of barrel next to the receiver, essentially the portion of the barrel before it begins tapering down. I have tried full barrel bedding before, and I've never had success with it. One of the problems with bedding a large portion of barrel is dealing with heat. As the barrel heats up and expands, it puts additional pressure against the bedding and your POI can shift. Sometimes, a bedding pad out at the end of the forend works well for slender "sporter" barrel profiles, but I've found that I generally get the most consistent accuracy from a fully floated barrel, though not always the absolute tightest groups.
If you want to bed the barrel, I've often heard recommendations from various smiths that you find the center of gravity of your barreled action (the balance point) and bed up to that point. Barrel blocks work very well, but they are generally only used with very heavy barrel profiles and extremely long barrels where you have a center of gravity and possible barrel sag problems.
One other solution you can try is a device called a "Bug Hole Tuner," which is really nothing more than a threaded sleeve you glue into your stock toward the end of your forend channel that has a setscrew with a saddle or wide pad at the end of the screw where it contacts the barrel. The head of the setscrew would be accessible from the outside of the stock. You simply use a hex key and slightly vary the upward pressure against the barrel until you achieve the smallest group size. You can easily make one of these or have one made. I have just such a device on a match grade Volquartsen "10/22" clone rifle. It works very well.
Edited by RifleDude |
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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RONK
Optics Master Extraordinaire Joined: April/05/2007 Location: United States Status: Offline Points: 3199 |
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I think that we sometimes look at things like this from the wrong angle. It seems to me that there comes a point when we should reconsider hanging a 3 or 4 pound barrel off the end of a 1 pound receiver. Wouldn't it just plain make more sense from an engineering standpoint, to bed that barrel firmly into the stock and let the action float free? It could still be done in a manner which would allow the barrel to vibrate or resonate somewhat freely,and such a concept may work best with a barrel-mounted scope. I would really like to see someone with more time than I have do some serious experimenting with this idea.
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Mike McDonald
Optics Journeyman Joined: September/01/2004 Status: Offline Points: 739 |
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Hot30,
Bed the barrel the way you want it and tune the load to the barrel. Don't try to tune bedding you'll go insane. RonK, Bench resters actually do this on heavy stuff. Not all that uncommon to see a 12" bedding block and a receiver hanging in space. Works well for those guys. My good rifles are bedded forward of the rrecoil lug about 4 inches. I arrived at that number becuase that's where the stuff stopped running out, and it looked good. Now that's about as un-scientific as it gets, but the rifles do shoot well. |
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Dale Clifford
Optics Jedi Knight Joined: July/04/2004 Location: United States Status: Offline Points: 5087 |
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Ronk that is pretty much what is done on AR type rifles also, 4 pound target barrel and 8 oz. aluminum receiver, with a flopply bolt carrier, and then the locking lugs in the barrel proper.
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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Exactly! Trying to tune bedding is a frustrating exercise.
Whether you bed action, barrel, or both, just make sure your bedding is stress-free. To check for proper bedding, if you have one, mount a dial indicator at the end of the forend and put the probe against the barrel. If the indicator moves more than about 0.003" when you tighten and loosen the action screws, your bedding isn't stress free, and you should either find and remove the stress point and/or skim the bedding with another coat of bedding compound and set the action in the stock without tightening any screws so the action doesn't flex while the bedding is curing. |
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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hot30
Optics Journeyman Joined: December/27/2006 Status: Offline Points: 378 |
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RifleDude, My action is currently mounted as you state in your last post. I did it this way with a lighter barrel weight before switching to this 1.120 "bull" barrel. Now I have been known to bed things just like Mike McDonald does, you know, "till the goop runs out".! Have had good like so far, but with this rifle its shows me so much potential I just want to get the max out of it. Its the rifle you know is a winner, just needs allittle polish. Mikes info about the good ones are bedded about 4" forward of the action is "good" working theory. I usually mix more goop than Mike, going out to arround 6". Now, this "bug hole tuner" perks me up a bunch.! Somewhere, cant tell you where, I recall someone building these things. Never saw any reviews on the thing so I lost track of it. Lets try this, my barrel is 1.120, no taper. I use Delrin for a lot of fixtures, so Ill build a saddle that can slide up and down the barrel channel under the barrel looking for a sweet spot. When it "groups" I will glue the thing down at that point and start "load tuning" from there. Stressing the barrel, lets say action, with this saddle is "taboo". Do have dial indicators to watch for this, and should be able to measure barrel sag be fore I start. Am I missing anything.?
Good one guys, 30 |
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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hot30, here's some info on the "Bug Hole Tuner." It's a very simple device, relatively easy to install: http://www.webspawner.com/users/bugholetuners/
Ironically, there has already been a tuning device created that works precisely as you describe, with a sliding Delrin saddle, called the Accurizer, made by a company called Aftermarket Innovations. However, I don't know whether the unit by itself is still available for sale. With this device, there's no need to permanently glue the Delrin block down, as the long screw keeps it in place, and you can tune to different sweet spots with different loads. The Delrin block rides inside a cast aluminum housing. If you have access to a machine shop, you can make a similar device pretty easily. I've installed one of these a few years ago, and it does indeed work. You mill out a channel toward the end of the forend to accept it, and drill a hole in the forend tip to access the screw that moves the Delrin block back and forth. Here is a photo of the Accurizer I installed in a stock:
However, the same company (Aftermarket Innovations) offers a stock with the Accurizer preinstalled, called the "Smart Stock." Here is the info on the Smart Stock. Click on the pic of the stock and it shows the Accurizer. http://www.rifle-accuracy.com/smartstock.htm
Some good info on barrel tuning at the Varmint Al's website: http://www.varmintal.net/atune.htm
Hope this info is helpful. |
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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hot30
Optics Journeyman Joined: December/27/2006 Status: Offline Points: 378 |
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Dude, could be the very thing I was trying to recall. I have my own shop, it used to build my race engines. Now I have all the equipment converted to gunsmithing. Right arround midnight I grab an arm full of my favorite poison and take a walk to the shop.! Its only a 75 yard stumble to the door so Im not hurting real bad when I get there.! Cant shoot out the door though.!!!!!!!!!!! Im going to strip the rifle down tonight and start the fab, lets see what happens. I recall that you shoot the 7mmWSM also. This round that we all thought was going to disappear is becomming real popular all of a sudden. Brass, dies etc. is bought up rather quickly these days. Better stock up.!! Dont get the idea that I build weapons under the "influence", but I do ..!!!!!! At least untill the goop runs out. HE, HE.!! When its all done, I will post pics. Mike will appreciate the gun Im sure, its right in line with what he does. You know how the gun slingers that like to be different are.??
Your pic of the tuner computes.!! All I need is "one" look and its a done deal..
Thanx,30 |
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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No problem, hot30!
I haven't had much success doing anything requiring skill while under the influence...but I have made the goop run out many times! So, I admire your determination and multitasking ability!
Just keep your fingers well clear of the endmill!
Keep me updated on your progress and definitely post pics. Make sure that if you have a tapered barrel contour that you tilt the tuner in the stock accordingly. Otherwise, you will increase and decrease upward pressure as you move the Delrin block back and forth across the taper. I've thought about building some "improved" versions of the Accurizer myself, but I just have too many projects going at the same time. I'm sure you understand!
Yep, I'm a fellow 7Wizzum shooter. Glad to hear that it is gaining some more fans. I only hope more manufacturers realize this and start making brass. If only Lapua would decide to play... Edited by RifleDude |
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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pyro6999
Optics Retard OT TITAN Joined: December/22/2006 Location: North Dakota Status: Offline Points: 22034 |
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i wish lapua would play too, i could use it for my 300wsm
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They call me "Boots"
375H&H Mag: Yeah, it kills stuff "extra dead" 343 we will never forget God Bless Chris Ledoux "good ride cowboy" |
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hot30
Optics Journeyman Joined: December/27/2006 Status: Offline Points: 378 |
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We all talked about the Lapua involvement on "reloading&ballistics" some months ago. At that time, I had contacted Lapua and they stated " not at this time".. The contact info was derived from " BRUNOs" shooting. I was given the name of the state-side rep and an E-mail contact for Lapua. If we all could express our interest in the WSM line-up they might move on this.?
Engineering under the influence, no need to worry.! I consider it an "edge on the competition". My imagination is opened to a new level once the everyday common clutter is subdude. |
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hot30
Optics Journeyman Joined: December/27/2006 Status: Offline Points: 378 |
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Just sent another E-mail to Lapua. Lets load the wagon on this, and see what happens.! Get to Lapua.com under marketing & sales and send them your request to please look at the WSM cartridge line-up.
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pyro6999
Optics Retard OT TITAN Joined: December/22/2006 Location: North Dakota Status: Offline Points: 22034 |
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i would be all for it, eventhough it may cost more for the brass i would gladly pay it for a superior product.
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They call me "Boots"
375H&H Mag: Yeah, it kills stuff "extra dead" 343 we will never forget God Bless Chris Ledoux "good ride cowboy" |
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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I'm in! |
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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pyro6999
Optics Retard OT TITAN Joined: December/22/2006 Location: North Dakota Status: Offline Points: 22034 |
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i sent them a message as well
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They call me "Boots"
375H&H Mag: Yeah, it kills stuff "extra dead" 343 we will never forget God Bless Chris Ledoux "good ride cowboy" |
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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Hey hot30, how is your tuner project going?
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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hot30
Optics Journeyman Joined: December/27/2006 Status: Offline Points: 378 |
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Funny you should bring that up. I liked the pic you posted, gave me some ideas. Rather than duplicate what I saw in the photo, Ive milled a .250 slot the entire length of the forearm. The delrin saddle was fashioned as a "T", where the post of the T rides up and down in the slot. Had alot of "barrel float clearence" in the forearm so it didnt take alot of material removal to make it fit. Now when I can get back to it, I will try and find that "sweet" spot.! |
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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Here's a tip I discovered with this type of tuner -- take a piece of sandpaper and work it between the barrel and tuner with the grit side toward the delrin block. Work it back and forth across the top of the block to get a nice form fit to the barrel. Sand material off the block a little at a time and see how your rifle reacts to the amount of pressure. You don't want too much pressure; just enough to dampen barrel vibrations. When you get a decent group, then move block location a little at a time to tune to the smallest group size. This is where the long all-thread screw is helpful so you can move the block without having to remove the action from the stock.
Good luck, and keep me posted on how this works for you. |
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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hot30
Optics Journeyman Joined: December/27/2006 Status: Offline Points: 378 |
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Rifledude, been awhile.. getting back to you on this barrel bedding thing. Its done and it works. After finding the node on this 6 lb barrel, took the delrin "T" out of the stock and layed in some bedding about 2" out from the recoil lug. The bed is also 2" wide at this point. Re-bed the action, recoil lug and the barrel as a unit. Oddly, I found some Federal ammo for the 7mmWSM. 140 gr Nosler BT and some Barnes 160 gr. Stopped by a buddys shop and there it was. Can you tell me if this Federal stuff is currently available or is what I found some discontinued attempt by Federal.?? I dont shoot factory ammo at all, just thought I would try these. If its current ammo, I might look at some Federal bulk brass, see if its worth anything.
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