Extra Metal on Long Range Rifles

[bjlooper]

Hi
I've noticed on some of the pictures of Long range rifles, that their is some kind of extra metal just in front of the barrel. This is new to me would someone explain the purpose of said metal and what is it called.
/ubbthreads/images/graemlins/confused.gifThanks
DR B

 

[James Jones]

I'm guessing that your talking about a barrel bedding block that alot mof heavy LR guns use and alot Bench rest guns to

Its basicaly a aluminum block that has a hole drilled through it and its split so it can be bolted around the barrel , its then bedded into the stock so that the top can still be removed but the bottom it glued into the stok and doesen't move or come out , when the barrel is installed and the top half is replaced then the whole action and part of the barrel thats out of the block are free floating.
It does about the same job as glass bedding a standard rifle but eliminates any stress to the action when you have a big heavy barrel
So guys don't use a block they just glue the barrel into the stock

 

[BountyHunter]

The barrel bedding block also does a couple other things.

1. Harmonically shortens the barrel to what is extending outside the block forward. For example, 30" barrel, with 9" block (extensive testing has shown this to be the best and max length) leaves about 21" sticking out front. The theory is short fat barrels are more accurate (easier to tune) than longer barrels.

2. Easy barrel changes. Simply unscrew the top block, lift the barreled action out and change barrels and clamp back in. No rebedding of the action required. Make sure that you use a "split" block. You can use a solid block that just has a hole drilled where the barrel is glued in but that is expensive and time consuming to change the barrel. The split block is the way to go.

3. Allows a 700 action with short tenon to be used with long heavy barrel and the barrel weight not destroy the bedding. The action is actually free floated and the bedding block has the bedding for the gun. Most of the blocks are pillar bedded on the bottom.

Heavy guns often use a solid block that is split. Light guns (16.5 or 17 lbs depending on organization) use a block that often has the middle cut out of the top for weight reduction. It is hard to make weight normally with a LG in a barrel block.

BH

 

[Bart B]

[ QUOTE ]
The barrel bedding block also does a couple other things.

1. Harmonically shortens the barrel to what is extending outside the block forward. For example, 30" barrel, with 9" block (extensive testing has shown this to be the best and max length) leaves about 21" sticking out front. The theory is short fat barrels are more accurate (easier to tune) than longer barrels.

2. Easy barrel changes. Simply unscrew the top block, lift the barreled action out and change barrels and clamp back in. No rebedding of the action required. Make sure that you use a "split" block. You can use a solid block that just has a hole drilled where the barrel is glued in but that is expensive and time consuming to change the barrel. The split block is the way to go.

[/ QUOTE ]
I'm not convinced that a short, fat barrel is more accurate than a longer one that's not very fat. The smallest groups of 10 or more shots I know of fired at 600 yards have been made with medium length and weight barrels. Same thing applies for 1000 yards. I know there's been some 5-shot groups at those ranges that are pretty small and impressive.

I'm not sure that a proper epoxy bedding job has to be done each time the barrel's replaced. Having worn out three .30-.338 Mag. barrels in the same Devcon Plastic Steel bedding over an 8-year period, each one was tested for 1000-yard accuracy with 15-shot test groups; once when the barrel was new and again after about 600 rounds. The largest group was just under 7 inches.

A friend was watched check out four .308 Win. barrels in his Win. 70 based rifle one afternoon. He would remove the barreled action from the Bisonite epoxy bedding, clamp the barrel in a barrel vise, unscrew the action with a receiver wrench, put another barrel in the vise then refit the action clocking it in to the witness marks he'd put on each barrel when he fitted and chambered them. The rebarreled action was put back in the stock, all three screws torqued to 60 inch-pounds, then the rifle was clamped in the sliding carriage of a machine rest. After shooting a 20-shot test group at 600 yards, the rifle would be rebarreled and another test group was made; all using the same lot of ammo. All the test groups were from 2.5 to 3.5 inches. He put the barrel that shot the best back into the rifle.

 

[Gunflash]

Is it the muzzle end , like the Browning A bolt has ?

 

[BountyHunter]

Bart

Understand "you" are not convinced, but lot of guys that shoot little bitty groups all the time are. Until the advent of large custom actions such as the 10" BAT that is 2" in diameter, almost all the Heavy guns in 1000 yard BR were barrel block guns and still majority of barrel block guns being built especially with the longer barrels. Historically 1k Heavy guns have shot the smallest offical recorded groups of any competitions.

However, there is now a new practice coming on that is going to the straight barrels of much smaller diameter that are "slugged" for proper bore dimensions of the bore and most importantly the muzzle end (ie jug choke) and exact crown points and tuners.

You are correct, if you order the exact same contour barrel every time you can normally drop in and tighten the action screws down. That is assuming the contour is exact and it matches perfectly the bedding in front of the rcvr that most smiths use.

BH