Thread: Zero MOA rail/base - why?

If they take the effort in making a rail/base, I see no reason why zero MOA base should still be made and sold. All rails/bases should have minimum 10 MOA. It is not like it is that hard to do. In fact, it is not even necessary that they are consistent. I would happily accept a new Ruger 10/22 with a rail that is rated between 10~15 MOA.

CMV.

ho hum....so lets pretend for one minute you have been good lad and all the stars were aligned the day rifle left factory,the scope rail is PERFECTLY aligned in both verticle and horizontal planes and your brand spanking new scope is clicked to dead centre in both planes,you put it in rings and its already pretty much spot on at 50 yards when you go to range.....and you now saying you want it to be pointing 10" low BEFORE you start......

giving you 40 less clicks of adjustment........

I suspect it's to appease a large number of buyers who do not understand why you would want to use a sloped base.

The only valid reasons are that a 0moa rail is a fractionally lower overall height for mounting, or that someone may want a highly robust mounting system to use with an optic that has limited travel available.

I would always opt for a cant/tilt in a base unless it is on a short-range bush rifle. Otherwise, if the scope is mounted on a 0 MOA base, a greater portion of the scope’s usable range of elevation adjustment will be wasted. The most common reason to opt for a 10 or 20 MOA base is because of the limited range of elevation adjustment in the scope.

Since all/most shooters don’t dial adjustments under their zero distance, the goal is to make most of the adjustment range on a scope dial-up to shoot out at targets further away. Ideally, if the riflescope has 40 MOA of elevation adjustment, 40 MOA will be available to dial up. Mounting a scope to a 20 MOA base makes that attainable.

Right, you have all missed some thing.
I have always put on a 20 moa base on every thing, until I needed a rifle for thermal and standard optic using qd mounts.
I was told by the thermal God I was better to use the 0 moa base so bought a steel ctr base of some good bugger of here and am away!


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Originally Posted by Micky Duck

ho hum....so lets pretend for one minute you have been good lad and all the stars were aligned the day rifle left factory,the scope rail is PERFECTLY aligned in both verticle and horizontal planes and your brand spanking new scope is clicked to dead centre in both planes,you put it in rings and its already pretty much spot on at 50 yards when you go to range.....and you now saying you want it to be pointing 10" low BEFORE you start......

You lost me completely.

Because some people buy red cars, some even buy Sang Yong! Some people wear jeans and some wear those ugly looking Chico things. Despite all the hype and hoopla we see in shooting forums about twiddling and fiddling with dial scopes, there is a huge section of out shooting fraternity that quite simply buy a rifle, put a scope on it, sight it in and actually go shoot shit. They dont dial, they have no need. So a 0moa base is perfectly adequate for a large number of people.

Some scopes don't have the tube length for bases particularly in a long action

Originally Posted by Husky1600

Because some people buy red cars, some even buy Sang Yong! Some people wear jeans and some wear those ugly looking Chico things. Despite all the hype and hoopla we see in shooting forums about twiddling and fiddling with dial scopes, there is a huge section of out shooting fraternity that quite simply buy a rifle, put a scope on it, sight it in and actually go shoot shit. They dont dial, they have no need. So a 0moa base is perfectly adequate for a large number of people.

Firstly, see the premise of the thread is that if one bothers to make a rail, it should be sloped. Many rifles do not come with a rail, People just mount rings and shoot, that is fine. Like you say, simple and straightforward.

Simple and straightforward is not always without problem. See the recent thread about a rifle can not zero, because scope has only 15 moa each way.

Those who end up buying a rail at all already tinker with their rifle.

Having 0-500m closer to the optical centre of the scope for better tracking and clarity.

It's hardly a concern nowadays, since glass and tracking on new scopes tends to be really good... But old habits die hard. Same reason they still make 270's.

I think the 0moa is just "safe" and probably saves gun manufacturers a lot of headaches.

Picture this, a rifle comes standard with a 10moa rail. In this case its just a regular mans rifle, not a super high end precision setup. The sort of thing that someone is probably expected to throw a cheap scope on. The cheap scope has 30moa of adjustment total. Now in a perfect world, all would be well. Without the rail he should be in the middle of his adjustment range with 15MOA up and 15MOA down, and with the rail installed he should have gained another 10moa, giving him 25MOA of upwards elevation. Problem is that never happens. A lot of the time the guy would not be able to zero the scope as it just never works out quite as it should and there isnt enough wiggle room with the type of scopes people would be expected to mount on this lower end gun.
I think gun manufactuers tolerances would have to be much higher in order to safely offer an MOA mount standard, on guns that people probably wont be putting a long range scope onto. If the dude with the 30moa scope cant get it zeroed with the 10MOA standard mount - whose problem is it going to be? The gun manufacturers, because in theory it should work, but in practice to get it to work failsafe, with scopes and rings whose quality you cant control - the guns tolerances is the one that has to be very high otherwise itll all come back to them. IMO.

Assuming we have a droop-free centrefire barrelled action that shoots 820m/s. when shooting horizontally it takes 0.12s to hit 100m. At t = 0.12 s, d = (0.5) * (9.8 m/s2) * (0.12 s)2 = 0.07 m. I.e. 7cm, or around 3 MOA, drop. On average, scopes are mounted about 5cm above the bore, measuring from the centre of the scope to the centre of the bore. At 100m, that higher difference is just under 2moa. Basically if you have a droop free barrel and perfect scope, you still need about 4~5 MOA to zero the gun at 100. Lets call this effect the "inherent slope".

The inherent slope is more pronounced on 22LR zeroing at 50m, because it takes 0.15s to reach target and drops 0.112m, i.e. 8 MOA. add the scope to barrel angle which is about 3.5 MOA for 50m you need about 11 MOA to zero the gun.

The inherent slope can be smaller if the scope is mounted lower, or if the barrel slightly points upwards (never happens by design), but it will never be negative - because you never mount the scope under the barrel and gravity always pulls downwards.

Guns where barrel is not screwed into the action, instead, is sled into the action and held by screws, such as CZ455/457 and Ruger 10/22, have the potential of barrel droop. This further increases the inherent slope.

This is why I think MOA rails is not just for dialling snobs, it is also useful to anyone who is shooting rimfire and also to those running long and/or slim scopes (that tend to have limited adjustments). sloped rail entirely removes the possibility of running out of adjustments before zeroing the gun.

Originally Posted by Ultimitsu

You lost me completely.

well thats not hard...... if your scope is centered,and your rings are centered and everything is lined up well,you dont need to use up any of available clicks to be on target...at most will use 12 clicks to raise point of impact .....and you will still have lots left....my .223 works like that. the scopes adjustment is just about dead center as the rings on it just work right.