Scope mounting: how close is too close?

matt308

Well-Known Member
I am about to put a 50mm objective scope on my 308.

The Leupold rings I have only leave 1mm between the scope and the barrel (which is varmint/heavy profile). You would think any gap was enough gap but I recall seeing a slo-mo of a rifle being fired and the barrel flexed at the moment of firing which would mean it hitting the scope. This will at best disturb the harmonics but more likely damage the scope, so I don't want to risk it. On the other hand I don't really want to have to buy more rings and it would mean keeping the same cheek weld/position if it works.

Am I worrying unduly? It's only a 308 after all, and I use a pretty mild load with 150gn heads, if that's relevant.
 
That gap should be fine with good rings firmly attached. Just ensure you keep the gap clear and clean regularly - especially when out in the wet as it will hold a water droplet and rust spot your barrel and scope.
You could always shim the rings slightly to give you a marginally bigger clearance if you remain unsure. Photo negative cellulose film works well.
 
I have tried to find some footage to confirm either way. Seems I may be worrying over nothing though. Thanks Eric.

​The scope is a Vortex so has a no quibble warranty. If nothing else it might let me see how that works in practice.
 
I think that further down the barrel the whip may be more pronounced but so close to the thicker part by the chamber I can't see it moving that much.. But its not my scope
 
I have ended up with a .005" gap on a .223rem
Never caused a problem, but as ETR said make sure you dry it off on wet days.

Neil. :)
 
was about to post another thread on this when I saw it has been covered.

I have however been thinking....
Having just swapped scopes to a target turret version I have a knats todger (its an official SI unit!) of a gap between a 50mm Obj and the barrel on my 300WM

now having seen this:


OK its a 50cal and a poorly designed mount but the flex is bound to be present to some degree in both barrel and scope

I am now wondering if it may touch under fire
 
I think you can rule out the barrel and action flexing that much (considering heat expansion too). Even the tip of the barrel wouldn't whip that much imo. The only bits that would flex more would be the scope body and scope mounts, and I think any decent scope and mounts are way too stiff to flex anywhere near that extent.
 
Surely the most flex will be at the unsupported ends of the scope tube and barrel muzzle rather than the supported mounts.
i think you will be surprised how much the barrel whips especially on slimline sporter barrels
the muzzle on mine is barely 15mm wide with a 7.62mm bore
thats barely a 4mm wall
 
I get what you mean, bewsher. The most movement will be at the end of the scope tube, but the flex/stress will be greatest just in front of the front mount. The biggest component of recoil is rearwards, effectively pulling the barrel, scope etc forwards. How much of the recoil is translated into muzzle flip? I think that the vertical loading (and therefore deflection) on barrel, scope etc are small compared to the loading along the axis of the bore.

I agree that the most movement when loading a cantilevered object (barrel, scope) is always at the end of said object.

I suppose only hard facts will clear this up.

Nice to have something engaging to mull over for a change.
 
I've just had a look on youtube to see some barrel whip videos. I think I stand to be corrected - some funny harmonics at play that I don't know anything about.

I still don't think that there will be that much movement around the scope area.

I do agree with you, bewsher, that the muzzle will probably move around the most.
 
I've had a 50mm objective scope set in low rings on my Tikka .308 and previous .243 both varmint now for over 6 years without any issues. It's set so close I had to cut a section out of the scope cover as it wouldn't slide between the scope & barrel.
Wingy
 
I also have 2 rifles with scopes not touching, but a lot less than 1mm gap; no issues, other than have to cut the butler creeks.
 
Good morning all, I know this is an old thread but I have just put a scope on a new rifle I have acquired and wondered your thought on if the scope is too close to the barrel or not. I can just about get a peice of paper between them. Many thanks.DSC_0656.jpg
 
Back
Top