One piece vs two piece bases

Discussion in 'The Basics, Starting Out' started by rimrockhunter, May 11, 2010.

  1. rimrockhunter

    rimrockhunter Member

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    Can u guys give me some input on advantages and disadvantages of one and two piece bases for use on my long range rifle. Am mounting up a IOR 2.5 to 10 on my 338 UM. Also, when do you need a base with built in MOA ?
     
  2. geargrinder

    geargrinder Well-Known Member

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    You need the tapered base when your scope doesn't have enough adjustment to let you zero at your farthest shooting difference.

    I don't mind 2 piece bases. My favorite are Burris Dual Dovetail with Burris Signature Rings.

    I think they are more secure than almost any other system, protect the scope from ring marks, and a cheap way to add taper.
     

  3. phorwath

    phorwath Well-Known Member

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    I believe a one-piece base is a more rugged support system than the two-piece bases. 4 screws holding one piece securely over a span of 4-5 inches of separation, compared to 2 screws holding two separate pieces with the screws separated over a span of only 1 inch. I always go with one-piece bases in order to improve the rigidity of the scope-to-receiver mounting system.
     
  4. royinidaho

    royinidaho Writers Guild

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    I agree fully with phorwath!

    I"m assuming you 10# RUM has a brake installed.

    If I'm correct a dual dove tail mounting system is the only way to go. I when with the rear windage system as that was what was handy when I mounted the scope.

    My 338 RUM also weighs 10# w/scope. First I couldn't keep the scope from sliding in the Leupold rings. The rear ring pealed the scope like a banana. Simultaneously the scope internals began to rattle. (Cabelas Alaskan Guide).

    Switched to Burris Signature rings with 20 MOA inserts. Torqued the ring screws so much that the wrench looked like it was threaded. Twisted it about one full turn. Rings have held for several years.

    However, the rear windage feature failed after maybe 30 shots. Went with the dual dove tail system with Burris Signature rings w/inserts.

    Things are as solid as a rock.

    Just my experience.....
     
  5. winmag

    winmag Well-Known Member

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    Each has its advantages/disadvantages. 1 pc tends to be more ridgid and a simple ''ramp'' for added moa of elevation. But more cumbersome for loading, and unloading and cleaning your rifle, and add more wt. None of wich I see as a pro...
    I only use 2 pc bases for the added room of loading and unloading. I havent had any problembs yet. But the 2 biggest hitters I have are the 300wby, and 338 win mag. I have leupold bases and rings on all my rifles from my 10/22 to the big stuff and all inbetween. with one exception, my 338 has 2 pc Burris rings and mounts (THEY WERE FREE, with the rifle. Cant beat that price:D). I removed a solid 1 pc base from my 300 wby and the same with my 30-06 and put on 2 pc bases because of what I see as advantages for rifle maintenence and loading.
    I am not bucking what the other guys are saying. Its obvious 1 pc mounts work well for them. They gave you the pro's of 1 pc. I gave some pro's of why I like the 2 pc. system. Personal preferance thing.
     
  6. phorwath

    phorwath Well-Known Member

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    I use aluminum 1-piece bases from Seekins Precision, TPS, and EGW. Weight is a factor with some of the steel 1-piece bases for packing rifles. One-piece aluminum bases are as light 2-piece steel bases.

    I also use Seekins aluminum rings to stay a step ahead with my packing rifles. And all my rifles are packing weight rifles.
     
  7. LongBomber

    LongBomber Well-Known Member

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    I pick my rings/bases based on what I use the rifle for. For a light weight packing rifle I like the talley one piece ring/base. Very light, and pretty solid. For a heavy rifle, or target rifle I like a rail and stong tactical style rings. Something like a Nightforce rail and rings, or a setup from Near manufacturing. Very strong, with the ability to handle more than just 2 rings if needed.

    I have a 325wsm that comes in at 6.8 pounds scoped and loaded. I got free Luepold windage adjustable bases with the rifle, the adjustment screws worked loose constantly, even with blue loctite. I broke off one screw at the range. This rifle has a very sharp recoil, not that hard but pretty quick. It ate 2 Luepold ultralite scopes with the Leupold rings/bases. I switched to the Talley lightweights and have no more problems, and it saved an extra few ounces.
     
  8. johnnyk

    johnnyk Well-Known Member

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    rimrockhunter,
    No real advantages or disadvantages to either system, only perceived. Two piece bases are just as strong as a one piece. The steel action is pretty stiff as is, and it only stands to reason if it flexes under recoil anything screwed tight to it is also going to flex.
    Aluminum weighs 1/3 that of steel. It also takes three times as much to get the same strength. Steel is much much stronger than aluminum. The modulus of elasticity (a measure of stiffness: 29,000,000 psi for steel and about 10,300,000 psi for aluminum) and the yield point (stress at which a material will deform and not return to its original shape) of steel are far greater than aluminum.
    With all that being said, I would say get what works and looks best to you. I have used the Leupold, Redfield and Burris STD and Dual Dovetails. The only failure I ever had with any was on a one piece Redfield STD base. A windage screw sheared off due to the recoil of a .300WinMag. Any of the dual dovetail bases with the Burris DD Signature rings are a nice set up.
    I have not used any of the Picatinny rail type bases and associated rings, mostly due to price. I can not conceive of paying 3-4 times the cost for bases/rings because, again, of perceived advantages, they're "cool" or Tactical has been used in their description. Like it or not, it is what it is. :) JohnnyK.
     
  9. phorwath

    phorwath Well-Known Member

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    I'll disagree. The whole issue is which scope mounting system if better able to resist forces that could cause a scope to shift position and lose its zero. I consider scope mount failures to include any time my rifles lose zero from a previous outing, and I've had that happen even with one-piece aluminum bases and aluminum picatinny tactical rings. So I refuse to return to use of two-piece bases which only increase the potential for a bumped scope to shift POI.

    The modulus of elasticity strength properties of steel versus aluminum? Are they really important when the scope tube itself is made of aluminum? Maybe so if the test is how hard one must swing a steel hammer to deform the base, rings, or scope. Are we to believe aluminum mounting systems lack the strength to fasten an aluminum scope tube to the receiver. I'm certain the thinner-walled scope will be damaged before the modulus of elasticity of aluminum bases and receivers are exceeded. The advantage of a once-piece base over a two-piece base is not related to forces that deform and destroy the base, rings, or scope, but the bumps and nudges that cause a shift in the scope's zero and subsequently result in a miss on a hunting shot. That's where the one-piece base mounted to the receiver at each end over a distance spanning 4-5 inches has the advantage over the two-piece base. Four screws holding one single base with the screws spaced 5" will resist higher force without movement much better than two screws spaced 3/4" holding the two separate bases on a two-piece base to the receiver.

    Any quality 1-piece aluminum base with aluminum rings will survive forces the aluminum scope tube itself will not, and will add less weight to a packing rifle than most any two-piece steel base and steel ring set. And a one-piece aluminum base will resist shifts in scope zero better than any two-piece base on the market that are held to the receiver by two screws separated by a distance of ~3/4 inch.

    Most custom receivers are equipped with one-piece bases. They are able to incur higher applied forces prior to shifting position on the receiver, compared to two-piece bases.
     
  10. johnnyk

    johnnyk Well-Known Member

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    So we agree to disagree? :) JohnnyK.
     
  11. phorwath

    phorwath Well-Known Member

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    Yup... I'm easy!
     
  12. johnnyk

    johnnyk Well-Known Member

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    I actually have steel one piece bases/w rings on my 700P 7Mag and a 12BVSS 6.5X284 and two piece bases/w rings on a 112BVSS .300WinMag and a M70 .243 (they're alumunum). I like 'em all! JohnnyK.
     
  13. specweldtom

    specweldtom Well-Known Member

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    All of the 1 pc. bases I can remember using (Redfield and Leupold) only had 3 screws. I started using 2 pc bases to get the 4th screw and to open up the ejection port. I have pretty much settled on the Burris Signature rings and dual dovetail bases or the Signature Z-rings and Weaver grand slam (steel) bases. I believe the Z-ring setup can hold zero better with a heavy scope than the dual dovetails. Just my opinion, no science. On the hard kickers, I drill out and tap the receiver holes for 8 - 40 screws. The holes in the bases have to be drilled out for the # 8 screws, and most bases have to be counterbored for the heads. The hardest kicker I have is a .460 Wby. With the Pendleton brake, Wby says 82 ft/lbs. I've got a 2 1/2 x 7 Leupold VX111 on it in 2 pc Leupold bases. I am going to change the whole rig to the Burris Signature Z-rings and Weaver Grand Slam bases. It's broken several of the cupped windage screws, chewed up one rear base. and rattled a 4X Leupold Compact. (Leupold replaced the scope without a whimper even after I told them what it was on). So far I've only put 18 rds on the VX111, and it's holding zero. The 4X compact had 50+ rds of .375 H & H and 112 rds of factory and handloaded .460 before it cratered. It's back on the .375 now.

    The Burris Signature rings and 2 pc bases are an easy choice for me. I like that the rings grip hard, don't mark scopes, and gimbal enough to avoid any misalignment stress on the scope barrel. The dual dovetails are neater, but the Weaver bases are sturdier. (I think).

    Just another opinion. Tom
     
  14. Boss Hoss

    Boss Hoss Well-Known Member

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    Put the Bases on like this (1 or 2 pc) and you are home free:

    First use 400 paper then steel 000 steel wool and acetone and rough the contact area of the receiver and then do the same to the contact area of the base.

    Use a cotton ball with acetone to clean any residual off of the receiver contact area and the base or bases. Set aside the base and be careful not to touch the clean areas. Use a little paste wax on the tip of a toothpick to apply into the threaded areas on the receiver. Apply a very thin layer to the screw threads and to the bottom half of the screw head. Set screws on a clean shop towel -- you get the idea.

    Now use JB Weld (regular not the quick set as it for what ever reason does not work as well) because it can be heated and removed easier should you want to remove this later on. Mix it and use just a little die if you have it to more closely match the color of the bases and receiver. After mixing on your little piece of cardboard or index card set aside for a few minutes.

    Get your propane torch and heat the contact area of the receiver and the contact area of the bases just enough to bring out any moisture that may be present on the surface. When the bases and receiver have cooled back to less than 100 degrees (this will not take long because you did not heat them up that much) using the toothpick that you used to mix the JB put a small amount on the receiver mating surface and on the base mating surface. Don't worry about it oozing now carefully place the bases lining up the screw holes as closely as possible and gingerly set the base on the receiver---immediately place the screws in the holes and get all of them started a few turns.

    Now that the screws are started give a turn to one and move to the next screw. Repeat process until they are all snug then tighten each one to its final tension. This is important-----DO NOT OVER TIGHTEN. We do not want all of the epoxy to be completely squeezed out.

    Now leave the rifle in the vise and let sit for 5 minutes or so (I use rubber inserts so that the barrel can be clamped in) and get your capful of WD 40, cotton balls and Q-tips. First use dry q tips to remove most of the excess then take a cotton ball and dip a small portion in the WD 40 and very gingerly wipe down the areas you just removed the excess JB. You will notice that it comes of very easy but make sure not to press to hard on the edges where the base and receiver meet we don’t want to disturb that line.

    Use the q tip or the tip of a toothpick with WD 40 on it to clean out any of the epoxy that migrated through the top of the screw holes an also into the openings of any of the screws.
    Now look at the underside of the bases where any excess JB could have migrated into the opening of the receiver or just on top of the receiver for example. Note where a one piece base is used it likes to hide underneath. For this area use the q tip with some WD 40 applied to remove.

    Now go off and have lunch about an hour and use the q tips soaked with WD 40 to smooth (gently) the lines where the base and receiver meet. If you have done everything correctly it should look like one piece of metal!!!

    In 24 hours or 6 using a light to position over the bases to heat them (keep under 90 degrees) you are ready to mount your scope.


    A final note here make sure to pre fit everything because it will really suck if you find out a base screw is too long and the rifle will not operate!!! Also make sure the base is level on the action---placing a base or a scope in a bind is bad juju for accuracy.

    If you ever bought a rifle from Speedy Gonzalez and had him glue on the base this is the way it was done.