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full-length bedding of barrel

stevecreastevecrea Member Posts: 486 ✭✭✭
edited August 2008 in Ask the Experts
I just acquired a used Sako AV in 25-06. It was manufactured around the late 1080s or 1990, and is known as an L61R Finnbear also.

When I dismantled it to clean it and inspect it, I was surprised to discover that the barrel appears to be full-length glass-bedded. I have heard of this, but have never had a rifle that was bedded this way. I also have a Model 75 and its barrel is fully free-floated, and that is what I expected to find on the older model. I suspect that the older model was fully bedded in an aftermarket operation, and did not come from the factory that way.

Would anyone have any knowledge of Sakos in this regard? What is your opinion about the accuracy and consistency of full-length bedding versus free-floating?

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    nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    stevecrea,

    Your full length bedding is an aftermarket process.

    Every barrel on every rifle is distinctively individual, especially considering the number of variables with ammunition and velocity. Barrels vibrate in a sine wave type of motion usually referred to as harmonics. They compress and they expand. The idea is to get to barrel to vibrate, compress and expand in the same manner repeatedly and consistently, each and every time. Load development is necessary to achieve the bullet's departure from the muzzle at the same time and at the same spot in the harmonic cycle.

    Barrels can be free floated, partially bedded, fully bedded or have a pressure point at some spot in the barrel channel that puts upward pressure on the barrel. This pressure point is the most common form of harmonic control used by the rifle manufacturers. But there is no one absolute solution that works every time, no matter what the gun writers write. It takes some experimentation.

    Common sense usually dictates that we try the rifle as it comes from the factory with known accurate loads. Then we go from there, either by removing the pressure point or removing all of the contact from the barrel channel completely as in free floating. Then if the barrel needs tuning, we add some bedding material or just a single pressure point at the very end of the forearm. If that fails, then we try a full length bedding or pressure bedding. And if push comes to shove after all of these fail, we tear the barrel off and replace it. It doesn't always come to this though. In many cases there is a sweet spot that can found with a load that has been developed for your particular rifle.

    One of the new fangled attempts to accurize the harmonics of a barrel is the Limb Saver De-Resonator. It's a rubber-type bushing that is slipped on the barrel and moved until the accuracy improves. It's just another form of tuner that the rimfire shooters are all hopped up about. Browning created one that they named the B.O.S.S. that was adjustable as an eccentric weight on the end of the barrel.

    That's the long way around the horn but hopefully it makes sense.

    Best.
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    stevecreastevecrea Member Posts: 486 ✭✭✭
    edited November -1
    Nononsense:
    Thank you for your response. I will shoot it and see how it does. I will plan to reload for it, but first I am going to shoot some HSM and Remington factory ammo.

    My objective was a longrange rockchuck gun, so I hope it will do under one MOA, if not better.
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    nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    stevecrea,

    Since this rifle is used, you should consider having your gunsmith borescope the barrel to check the condition of the throat and the bore. Clean the inside of the barrel carefully but thoroughly in order to get the best visual assessment from the borescope.

    It will be a great longer range chuck rifle.

    Best.
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    stevecreastevecrea Member Posts: 486 ✭✭✭
    edited November -1
    Nononsense:
    I cleaned it thoroughly with Hoppe's Benchrest, patches, and a nylon brush. I have not had it borescoped yet, but the condition of the rifle would at least imply that it has not been shot excessively. Further, it is my perception that Sako barrels are well finished, so excessive "break-in" may be unnecessary. However, during the time period of late 1980s or 1990 that this rifle was manufactured, it is possible that my perception is incorrect.

    I then mounted an old Leupold 4X, and shot it at 120 yards with Remington 100 PSPs. So far, so good, if not highly impressive. Three shot groups were running about 1.5 or 1.75 inches at 120 yards. It was warm, about 90 degrees, but I was careful to allow cooldown, kept the rifle in the shade, and kept the ammo in the shade. However, several rounds extracted with some "stickiness", indicating a little pressure. So I gave it up.

    I will work up a handload, and mount a higher magnification scope.

    Thank you for the input.
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    nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    stevecrea,

    "I cleaned it thoroughly..."

    Excellent! Too many of us get excited when we acquire a new-to-us rifle and immediately run out to shoot it. You don't have to borescope it but this will show you magnified details of the bore, throat and muzzle in case there is some wear that you should know about. In any case, you can use a piece of white paper held in the action while looking down the muzzle. Reflect some light off the paper and look down the bore at the paper. A vise comes in handy. You can also remove the bolt and shine a light down the bore from either end while looking through the opposite end. This is a little harder on your eyes.

    "...so excessive "break-in" may be unnecessary."

    Sako and Tikka barrels have generally had a good reputation throughout their history. If the rifle has been fired at all, I wouldn't give any thought to a 'break-in'. I don't do a 'break-in' per se. I use my load development as a break-in if you want to think of it that way.

    The lower power scopes are great for hunting but not much for assessing accuracy at 100 yards. Working up your own loads should maximize the accuracy from your rifle.

    Good Luck and let us know how this works out!

    Best.
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    glabrayglabray Member Posts: 679 ✭✭✭✭
    edited November -1
    Several decades ago we used to do full length barrel bedding on a lot of bolt action rifles. The results were mixed. On some rifles the accuracy improved dramatically while others showed little response. The most improvement was usually seen on guns with thin, whippy barrels. Apparently it reduced the amount of barrel whip on firing. Sometimes the downside was point of impact shift with temperature and humidity changes.
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    stevecreastevecrea Member Posts: 486 ✭✭✭
    edited November -1
    Thank you to everyone for the good input!

    I took the Sako with the full-length glass-bedded barrel to my gunsmith the other day, and he is going to inspect it, and give me his recommendations. He is also going to recrown it. It appeared to have some smaller imperfections on the crown, but that is such a critical area, that it is worth it to spend a little money there.

    He is also going to slick up the trigger. It was breaking at perhaps 4 lbs, and while that is not too bad, I like them closer to 2 lbs. The Sako triggers are very good, in general.

    He is also going to disassemble the bolt and clean it, as it was just a bit sticky, having been stored quite a few years, and had some congealed lube gummed up in it.

    After that, I will mount a higher power scope and work up a load for it. My objective is 5/8 MOA or better with a fairly hot load in the 75 to 100 grain range.

    If any forum members have some good, accurate loads for varminting with a 25-06, I would love to hear your input.
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    stevecreastevecrea Member Posts: 486 ✭✭✭
    edited November -1
    And I forgot to add, he is going to make "stoney point gauges" for all of my varmint rifles, which, many of you know, places the bullet very near the lands, helping to add to potential accuracy.
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