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July 10, 2006

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The Facts About Bedding a Rifle Barrel

A while back the subject of bedding a barrel came up, and was shunted aside for something more glamorous. But it’s important, and here’s some stuff worth knowing:

When a rifle is fired, its barrel twangs; I’m told by an engineer who has studied the subject that if you could watch it in slow motion, the tube would appear to appear to shimmy like a snake (waddle like a duck; that’s the way you do when you do the huckle buck).

Anyway, the purpose of bedding the barrel is to make sure the damn thing shimmies exactly the same way for every shot. The easiest way to bed a barrel is not to bed it—free-float the sucker from where the chamber swell tapers down right out to the end. Then let it do whatever it wants. Most factory rifles are made this way because it’s cheap and usually works very well.
Melvin Forbes of New Ultra Light Arms beds his fore-ends so they just touch the barrel. There’s no pressure, but there is a dampening effect. Melvin is able to do this because his Kevlar-graphite stocks are as rigid as I-beams, and once they’re bedded they stay put forever.

Top-line custom gunmakers who work in wood have long believed in full-length bedding (you need good, dry wood and a lot of skill to do this), and some of them like to shape the fore-end so it puts upward pressure on the barrel, although there are people who will tell you that wood being what it is, there’s no real way to achieve this.

Reinhart Fajen, the stockmaking company of yore, used a variation on this system. They’d free float the barrel except for two little bumps that sat 45 degrees apart about 2 inches back from the fore-end tip. This system was supposedly immune to the problems of full-length bedding, but had the same overall effect.

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Comments

mike shickele

Just to play the devils advocate; even if a fiberglass stock is as rigid as possible, would it still not move enough to change POI? Even my fiberglass stocks are free-floated to ensure thatthey don't move with extream weather changes. The problem with any barrel bedding is that there has to be NO movement period in the stock for it to work.

Dave Petzal

Mike: It depends on the stock. I had one synthetic stock back in the 80s when they were pretty primitive that shifted a foot on me. However, a good synthetic stock will not budge. I have both fiberglass and Kevlar stocks that haven't moved in 10 years.

Mark

Beddings! Know just enough to have dangerous opinions.

My ex-father-in-law…who got me into building rifles, loading, and varmint hunting…had one of those fore end gadgets that were adjustable to put fore end pressure on the barrel. The guy was always fiddling with the gadget’s adjustment screws.

I read somewhere…maybe from a J. Carmichael essay in that OTHER MAGAZINE…barrel weight tended to flex and bind Mauser and Enfield actions when free floated. To counter this I always glass bedded my barreled actions up to the first four or five inches of barrel. This tact has been very successful for me since I’ve yet to fall for synthetic stocks.

- I got into the habit of shredding a steel wool pad into the glass bedding mixture to strengthen and stabilize the bedding.

-I always clear the bedding from the front of the recoil lug with a narrow chisel, too.

Later.

Gary

Shucks, I bed all the actions and flaot the barrels on my varmint rifles. And as of now, it has proved to be an improvement on each one. Some years ago I went overboard and bedded the action on my .22 Remington (it was a long winter)and this proved to be of no value at all.

Rick

Bedding was intended to stabilize the reciever to the stock. With the bedding being done at the front barrel screw and recoil tab. Approximatily 2 inches behind the screw if posible and 2" to 2 1/2" infront of the recoil tab. If the front trigger guard screw is the front barrel screw, then it needs to be bedded also. This will give a solid screw platform and barrel bedding. Then free float the barrel by having the stock approximatily 0.005" to 0.007" away from around barrel. Starting at the front of the bedding to the end of the stock.

Think about it, I have seen factory stocks, not bedded, both wood and synthetic, that are tight on one side then the gap is on the other side when the weather changes. So the stock is constantly moving around in different weather changes. If you do not believe it, then take a rifle with a factory stock that has not been free floated and try to run a dollar bill between the barrel and the stock from the forearm to just before the reciever at different times of the year in different humidities.

Engineers say they have seen as high as 30 pounds of pressure on a barrel in extreme weather. If you have intentionally preload a pressure on the forearm tip, just think how high the pressure could be during the extrem conditions. That is why I bed at the recoil tab and do not allow the forearm of the stock to touch the barrel. I'm very satified with the 5 shot 0.39" groups at 200 yards.

Roger Swalls

What can I use for a good release agent. and what to use for color pigment in epoxies.




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