Thread: Zero MOA rail/base - why?

also a level base is in effect just a piccy rail........ plenty of reasons for fitting one,like has been said often times it makes eye relief and scope positioning easier on a long action....lots of modern scopes dont fit a long action well,with stuff all wiggle room so eye relief or speed to acquire sight picture effected.

Just going back in time, like pre 90's when there were probably not even 5 companies worldwide making sloping rails. Everybody was using 0 Moa mounts. Worst case they would shim the rear to gain a bit of elevation ( at the risk of bending the tube).
The demand has evolved and so has the industry and there must be at least 20 to 30 companies if not more that offer inclined rails and some with all the options in between.

If machining a 0 Moa rail is resonnably strait forward ( more or less), as soon as you make a canted rail you multiply the number of operations.
Take a tikka rail for exemple:
At 0 Moa: top and bottom are parallel, and the screw holes and screw head recess are straight and 90 degrees to those parallel surfaces.

At 20 Moa ( or any other angle): your screw holes and head recess are drilled at 90 degrees to the bottom of the base , but all your picatinny slots are milled on a different plan parallel to the angle of the top surface. Which can involve a few more operations depending on what cnc set up is run.

Just that makes the price go up, or the manufacturer does not want to bother and just make and sale 0 Moa rails only and that is it.

Originally Posted by Friwi

If machining a 0 Moa rail is resonnably strait forward ( more or less), as soon as you make a canted rail you multiply the number of operations.
Take a tikka rail for exemple:
At 0 Moa: top and bottom are parallel, and the screw holes and screw head recess are straight and 90 degrees to those parallel surfaces.

At 20 Moa ( or any other angle): your screw holes and head recess are drilled at 90 degrees to the bottom of the base , but all your picatinny slots are milled on a different plan parallel to the angle of the top surface. Which can involve a few more operations depending on what cnc set up is run.

Just that makes the price go up, or the manufacturer does not want to bother and just make and sale 0 Moa rails only and that is it.

But the majority of rails on the market are the same price for 0 MOA and 20 MOA.

It is cheaper if there is no rail and only built in dovetail or 2x weaver base.

Canted rails angle the objective closer to the barrel, which may mean you have to go to higher rings to get clearance.


Sent from my iPhone using Tapatalk

A 20 moa rail has a difference of height of about 1mm over 200mm of length.
So hardly more than a couple of mm for the longest scopes at the front objective end.
Sometime just by switching the brand of rail you can get that 1 or 2 mm extra of height and keep the same low rings for clearance Over the barrel.

A while ago I did a bedding job for a fellow member and when he dropped the gun of he asked if I could remove the 0moa rail and fit a 20moa. "You just keep it, maybe you can use it someday.

Bought a Delta Stryker for competition and thought "what the heck, why by a new 20MOA, I've got a rail, 0moa but still, it was free".

Much to my surprise I'm able to dail out to 1400m with ease.

Maybe I just got lucky, I dont know, I recon its made possible by the Deltas huge elevation capability.

Originally Posted by Jaco Goosen

A while ago I did a bedding job for a fellow member and when he dropped the gun of he asked if I could remove the 0moa rail and fit a 20moa. "You just keep it, maybe you can use it someday.

Bought a Delta Stryker for competition and thought "what the heck, why by a new 20MOA, I've got a rail, 0moa but still, it was free".

Much to my surprise I'm able to dail out to 1400m with ease.

Maybe I just got lucky, I dont know, I recon its made possible by the Deltas huge elevation capability.

Delta Stryker has 100 MOA of dial, that is 50 on each side. Assuming perfect parallel action and barrel, you would had about 45~MOA left to dial after 100m zero. 45 MOA would take a 6.5 Creedmoor to 1450 yards. With extra 20MOA, 6.5CM can go to 1750 yards.

It's best if possible to be near the scopes optical centre at the most common long range to be shot.
Also barrel indexing in a factory rifle is a lottery. It could end up at 6 o'clock ish which would mean some available elevation is lost.
And don't expect factory barrels to be perfectly straight in profile or bore centre to outer. Nor some custom barrels.
At least with a custom barrel fit it can be indexed to 12 o'clock which will aid elevation and give a best harmonics outcome.

Zero angle bases are easier and cheaper to make. Most centrefire rifles are never used beyond 300 metres and .22's beyond 100 metres so there is absolutely no point in fitting an angled base as those ranges are well within the adjustment range of all 'scopes. In the past I have made adjustable elevation bases for special applications but they were very few. Long-range shooting is really the only use for angled bases. Plain and simple works for professionals and bling sells well to the amateurs, a rule of thumb that applies to all technology-based endeavours.

Ah, bling...

Originally Posted by gundoc

Most centrefire rifles are never used beyond 300 metres and .22's beyond 100 metres so there is absolutely no point in fitting an angled base as those ranges are well within the adjustment range of all 'scopes. In the past I have made adjustable elevation bases for special applications but they were very few. Long-range shooting is really the only use for angled bases.

Oh I have seen scopes that would not shoot to 100m on a 22lr. Scopes with less than 40 moa adjustment already unable to guarantee that it would zero at 50m, going from 50 to 100 meters neds about 9 moa which many scopes would run out.

While cheap guns are more prone to this problem, better guns and scopes are not immune.

I have a Zeiss V6 5-30 mounted on an anschutz 54ms. This scope has 60 MOA of travel. With 50m zero and a 30 MOA one piece mount, I have 40 MOA adjustment left. This means if I didnt have the 30 MOA mount I would have only 10 MOA left.

I have a Weaver GS 4-16 on my Lithgow. It's rated at 40 MOA E and W. With a 50 yd zero I have no trouble getting to 100 yds (Up 7.75) and still have elevation left. Haven't quantified how much though.
150 yds would be a test. Need ~ 9 MOA to get from 100 to 250. I can also use the reticle grid if needed.
And then another maybe 10 MOA to get to 200 yds. Mmmm, I don't think so for me.

Originally Posted by Ultimitsu

Oh I have seen scopes that would not shoot to 100m on a 22lr. Scopes with less than 40 moa adjustment already unable to guarantee that it would zero at 50m, going from 50 to 100 meters neds about 9 moa which many scopes would run out.

While cheap guns are more prone to this problem, better guns and scopes are not immune.

I have a Zeiss V6 5-30 mounted on an anschutz 54ms. This scope has 60 MOA of travel. With 50m zero and a 30 MOA one piece mount, I have 40 MOA adjustment left. This means if I didnt have the 30 MOA mount I would have only 10 MOA left.

Clearly there is a horizontal alignment problem between the receiver and barrel with your rifle to have to use that much adjustment to get a 50 metre zero. 10 MOA is enough adjustment for 230 metres so the angled base is needed in your case to correct the misalignment. The alternative would involve bending the barrel very slightly to achieve correction (it sounds drastic but is the proper way to do it, subject to having the knowledge and equipment).

Yeah.. this is an Anschutz from 1995, shoots like a laser, so, I am not going to bend it.

My point is that many rifles have this "problem", if you call it that. Even the good ones.

My KIDD supergrade (first version) also has eats up a lot of adjustments before it is zeroed. This one is different to normal 10/22 in that the barrel is threaded into the receiver and the rail is part of the receiver (milled form one single piece of aluminium). so it doesnt even have the usual 10/22 droop.

I was shooting a Anschutz 1712 today, its owner complained that the scope only had 6 Mils left with a 50m zero. It is a Viper PST Gen 1 which has 20 Mils in total, 10 on each side. Zeroing it ate up 4 mils, which is about 14 MOA.

for 22LR shooting match ammo going from 50m to 230m takes about 33 MOA. I know cos I was shooting it just today. here is a video, excuse the bad quality it was shot with a phone (one with 5x optical zoom, crazy!)

https://youtu.be/Xiiz_wqnrMc