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Bedding under the barrel... yes or no?

Discussion in 'Gunsmithing and Repairs' started by Newtosavage, Mar 15, 2017.

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Bedding under the barrel - yes or no

  1. I bed under the action, and the first inch or so of the barrel

    14 vote(s)
    51.9%
  2. I bed only under the action and free float the entire barrel

    10 vote(s)
    37.0%
  3. I don't think it matters

    3 vote(s)
    11.1%
  1. 243winxb

    243winxb Member

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  2. Bart B.

    Bart B. Member

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    That's another first for me. Never heard of it.

    My post 64's never did. The couple hundred Winchester Palma rifles made for the Int'l Match at Camp Perry in 1976 didn't have them; just plain free floated barrels without shims. In fact, people on that team I know said they all had to ensure there was at least 1/16" clearance from all around the barrel to the fore end; a few did not and the wood was relieved. Nobody shooting best scores wants anything between the stock fore end and barrel to press against the barrel with different external pressures on the wood fore end.

    It's interesting that none of the M1 nor M14 match rifle's wood stocks warped in storage enough to matter. Even though their barrels had a few dozen pounds of down pull by the stock ferrule on the lower band. They all held zeros quite repeatable.

    Please explain the physics as to how a wood stock warps without a plastic shim between fore end and barrel but not if the shim is in place. Which of the five warp types is most common?
     
    Last edited: Mar 18, 2017
  3. Bart B.

    Bart B. Member

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    What matches, targets, rifles, ammo and scores were used; specifically?

    Of course, that was common in the early to mid 1900's with M1903's, M1917's, Winchester 54's and 70's. Highest scores were shot on big targets with 3 to 4 MOA high scoring rings with 2 MOA match ammo/rifle as the norm. That all changed in the 1960's when 2 to 3 MOA target high scoring rings came about and 1 MOA ammo/rifle was needed.
     
  4. Dog Soldier
    • Contributing Member

    Dog Soldier Member

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    Now that is interesting history. :rofl:
     
    Bart B. likes this.
  5. Newtosavage

    Newtosavage Member

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    Sorry this turned into a whizzing contest. I think I know who to believe now though. LOL Did I mention I shot a sub-MOA 6-round group the other day without waiting between shots, all after I relieved the bedding epoxy under the chamber of my 77? :D
     
  6. Bart B.

    Bart B. Member

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    Yes, I think you did.

    I didn't mention that full length sizing of fired cases has been the standard in benchrest events for several years. And done right, dozens of reloads per case is easy with maximum loads.

    I'm awaiting an answer about shimming the barrel in front of the bedding pad to prevent barrel droop:
    What prevents the barrel in front of that bedded section from drooping after that shim is removed?

    Better yet, isn't the barrel drooping from the shim forward while the epoxy cures?

    243winxb, where are you?
     
    Last edited: Mar 19, 2017 at 10:14 AM
  7. LoonWulf

    LoonWulf Member

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    My understanding was that shimming the barrel infront of your bedding during the curing process then removed, was mostly to keep the barrel from "drooping" (makes me snicker thinking about a sad barrel) and touching the stock, not actually supporting the barrel. This would be instead of, or in addition to opening up the barrel channel more.

    Otherwise i assume a pressure pad at the front of the barrel channel, or bedding the full length, would used if one were actually try to create pressure, support, what have you, on the barrel.
     
  8. Bart B.

    Bart B. Member

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    That would transfer all external pressure on the stock fore end directly to the barrel. Those forces vary with how the rifle's held and rested. The barrel would bounce off of it as it vibrates in all directions while the bullet goes through it. Vibrations have amplitude.

    Bad idea.
     
  9. stoky

    stoky Member

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    Even at lower altitudes, there are sticks and leaves and entomological wonders. Some folks take their rifles other places than from the SUV to the mat on the firing line.
    ymmv
     
  10. shootstraight57

    shootstraight57 Member

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    I am surprised that nobody is talking about consistent barrel flex with a free floating a barrel? This is one of the advantages of a free floated barrel. When bullet travels down a barrel you get harmonic vibrations. You want these to be consistent shot after shot. Just my opinion.
     
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  11. stoky

    stoky Member

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  12. Bart B.

    Bart B. Member

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    Those vibrations start when the firing pin smacks the primer. They get bigger when the round fires. There are several different frequencies involved. They quit after the bullet is past the muzzle.
     
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  13. Newtosavage

    Newtosavage Member

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    I don't think anyone is going to argue with Bart. I know I'm not. LOL Esp. after the results I saw. From now on, it's bedding the action only for me. Plus it saves me epoxy! Maybe Larry Potterfield should change his glass bedding video to show bedding only the action so as to not mislead too many folks?
     
  14. Bart B.

    Bart B. Member

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    He won't change the video. Some people believe barrels bend only in the chamber area; they're always straight forward from that so an epoxy pad past that bend point keeps the barrel straight.

    I've asked dozens about that as I did twice in this thread different ways; nary an answer came forth.
     
    Last edited: Mar 20, 2017 at 6:35 PM
  15. murf

    murf Member

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    It has nothing to do with barrel "droop" and everything to do with tuning the barrel for tiny groups. The same way you tune a pre-64 model 70 using the barrel lug screw.

    murf
     
  16. Bart B.

    Bart B. Member

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    Ah, yes.... Winchester's early fore end screws threaded into the lug under the barrel. Their first National Match Model 70's had that as well as their sporters. All the folks shooting best scores with them took that screw out and opened up the barrel channel to free float the barrel. I've reworked a few that way myself.

    That was a carryover from their Model 52 rimfire 22 target rifles. The early ones had a barrel band clamping the fore end to the barrel. Smart folks took that off because it transferred external pressures to the fore end to the barrel. Winchester finally got smart and left it off the Model 52C, D and E models that competed equally with the Anschutz rifles with their free floating barrels.

    Remington got permission from All Freeland to put his barrel-tuning screws in their first Model 40X rimfire 22 target rifles. Angled diagonally from the fore end tip to the barrel at 45 degrees up from both sides, they were supposed to "tune" the barrel vibrations for best accuracy. A battery connected to a light through the barrel and a screw was used to set each screw to zero as it barely touched the barrel. Top classified competitors tried that but gave up quickly; better scores were shot with totally free floating barrels. Point of impact changed quite a bit across standing, kneeling, sitting and prone with those screws transferring external forces to the barrel. Several thousandths spread across the zero point for each screw happened across different ways the rifle was held. Fore ends bend; honestly, they do.

    I remember when the first synthetic stocks came out for M14NM and M1A match rifles. As they laid in the sun and heated up, their fore ends bent in different directions. Zeros attained early in the morning were no good in the late afternoon, They changed a couple MOA; or more. Different pressure on the barrel from the fore end as it was clamped to the barrel by a band and ferrule. Garands had the same problem. Finally, synthetic stock makers used more temperature stable materials. Those shooting bolt guns with free floated barrels with a lot of clearance to those early fore ends had no problems.

    Accuracy/precision requires reducing all the variables to zero; or so darned close it doesn't matter. First thing one must learn is what causes those variables. Then learn how to correct for them.

    Next.
     
    Last edited: Mar 21, 2017 at 11:05 AM
  17. murf

    murf Member

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    Ah, the things done to improve accuracy. my Ruger no. 1 has an accurizer screw in the fore end (doesn't help accuracy, but was fun to install and play with). the pre-64 model 70 has the barrel lug screw removed and has the stock relieved under the lug (barrel free floated) for best accuracy.

    the reason for bedding is to stress relieve the action. Putting any uppward pressure on the barrel adds stress to the action. I think the fore end pressure point is used on production guns to make up for poor fit of the stock to the barreled action.

    free floating the barrel is the way to go imo!

    murf
     
  18. Bart B.

    Bart B. Member

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    All actions (receivers) epoxy bedded have stress and are slightly bowed upward in their mid section by the free floating barrel weight. If the barrel is full contact bedded in the fore end, the receiver may not be stressed until the round fires; then it will be stressed.

    Therefore, I disagree with that premise. I've measured receivers bending and short, skinny barrels don't bend them as much as long, heavy ones. It's all simple physics and mechanics.

    Receivers wiggle and bend just like barrels after the round fires. Bedding them makes them go back to the same place for every shot. They also twist from barrel torque; moreso with round ones compared to those with flat bedding surfaces.
     
    Last edited: Mar 21, 2017 at 1:18 PM
  19. murf

    murf Member

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    all actions, regardless, are under the stress of gravity. I don't consider that stress in this context. there are those that wrap the barrel with electrical tape (about half way down the fore end) before bedding the action. does that take care of the stress on the action? I doubt it. to me, that would be as bad as using a fore end shim.

    gravity is a constant and should not be "adjusted for" in this context (imo, of course). like bart b. is saying, the barrel will come back to its "drooped" state every time. just try to take care of the "man-made" stresses on that action.

    murf
     
  20. Newtosavage

    Newtosavage Member

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    So with all this in mind, what's the best way to secure an action in the bedding compound while it sets?
     
  21. Bart B.

    Bart B. Member

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    One way is to put O rings on the barrel to rest it in the fore end channel while the receiver floats in the epoxy.

    Another is to put a cofferdam in front of the receiver to support the barrel as it and the receiver go into the epoxy then tighten the tang stock screw until the barrel is raised up then centered in its channel.
     
  22. Newtosavage

    Newtosavage Member

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    See, I've never even heard of those two methods.
     
  23. murf

    murf Member

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    here is the pre-64 standard model with the barrel lug screw removed and the stock relieved underneath. the barrel is, as i remembered, free floated its entire length:

    0324171915.jpg recoil lug recess bedding

    0324171914a.jpg barrel lug stock relieved

    0324171925.jpg barrel fully free floated (dollar bill is touching the front of the reciever)

    and a custom pre-64 with a shilen barrel that has a bedding pad under the first four inches of the barrel.

    0324171931.jpg the custom rifle was built in the late sixties/ early seventies and bedded in the normal way (support that heavy barrel!) chambering is in 220 swift improved tightneck, fwiw. i have another stock pre-64 chambered in 220 swift (fully free floated barrel) that will out shoot this one. go figure.

    murf
     

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