Scope Bell To Barrel Clearance?

Discussion in 'Long Range Scopes and Other Optics' started by ZSteinle, May 27, 2012.

  1. ZSteinle

    ZSteinle Well-Known Member

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    How close is too close is basically my question, my scope is very close! Hard to get a good picture but the gun shoots great but just a little worried about it in extreme weather conditions (conditions that I have not shot it in yet with the scope this close). It has an easy .005 of inch maybe a little more, no feeler gauge to measure though.

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  2. Gene

    Gene Well-Known Member

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    I would not want it that close - the heat from barrel expansion after a shot or so could cause it to touch; not good.
     

  3. ZSteinle

    ZSteinle Well-Known Member

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    Thanks gene. Went and purchased a feeler gauge and it was only .002" moved the scope forward a bit to get .015". I'm thinking that should be plenty
     
  4. Bart B

    Bart B Well-Known Member

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    That barrel won't expand enough from heat to touch a scope bell 2 thousandths above it. If barrels really expanded that much, their bore and groove diameters at that point would be large enough to cause serious accuracy problems. Folks shooting 26 to 30 caliber magnums once every 20 to 30 seconds for 20 to 30 shots get barrels very hot in long range matches. All bullets fired shoot well under 1 moa. There's more barrel and scope bell movement at that point from both whipping up and down when the rounds fired than any barrel expansion from heat will cause.

    I'd get at least 1/16 inch clearance and more may be best on a hunting rifle. That way, if the rifle bangs around and something smacks the scope front bell, it will bend a little bit and still be usable after sighting in again. Otherwise, with near zero clearance, the bump may break the objective lens and then you get to use iron sights or buy the dream scope you've always wanted.