How many MOA is needed?

[koiloco]

Hi all,

I have a 50 DTC with a 36" barrel and a scope with 65 MOA total elevation adjustment. My goal is :

1. Zero at 100 yards
2. Be able to reach out to 2000 yards by dialing up.

How many MOA would I need in the base cant to achieve this? Is what I want to achieve even possible?

Thx for your help. I am new to long distance shooting.

[JMP]

65 is about the bare minimum you need; it might not be enough to hold center at 2,000. You'd need a cant that is as large as possible, but still allows a 100 yard zero. You need the full 65 to dial up, but that isn't a guarantee. If you can't make it, you can hold over with the reticle. Personally, I'd get a scope with more elevation.

[Switchbarrel]

Hi all,

I have a 50 DTC with a 36" barrel and a scope with 65 MOA total elevation adjustment. My goal is :

1. Zero at 100 yards
2. Be able to reach out to 2000 yards by dialing up.

How many MOA would I need in the base cant to achieve this? Is what I want to achieve even possible?

If you know your velocity & intended bullet, you can get a pretty good idea plugging the numbers into a ballistic calculator like JBM or some of the others out there.

For example, JBM says a 750gr. A-Max doing 2600 fps (69* & 900' Elev) would need about 79.6 MOA to reach 2000 yards from a 100 yard zero. I don't shoot a .50 cal so I'm only guessing at the velocity.

I've shot my .284 out to 1800 & the numbers were pretty darn close.

-Rick

[btm]

Just curious, why a 100 yard zero? You are giving up a lot of adjustment.

[LynnJr]

Your cartridge us very capable but your right on the edge with your scope and a solid base.
We shoot at around 4000 feet of elevation and with the 750 and 800 grain bullets you need right around 65 moa to hit the gong.
If your shooting the 660 grain full metal jacketed bullets you need about 85 Mia to hit the gong from a 100 yard zero.
A new scope would solve the problem but it would also cost you $2000.
You could try a 30 MOA base and see if it works and if not get a 40 MOA base but only with the solid bullets.
Your cheapest option is still $400 but it will get you to 3500+ yards.
The MOAB or Cold Steel base runs $400 and comes in either 150 MOA or 300 MOA.
I would get the 150 MOA base and the extra long adjusting nut for $60 more. That lets you leave your current base alone without any alterations.
You dial it dead on at 100 yards and when you want to shoot at 2000 yards you twist the knob to 60 moa and dial anymore with the scope.

[kcstott]

Speaking as a complete rookie, 1 I would need to play with a Moab to see how repeatable it is. I'd be worried about slop and potential windage issues. but I've never had one in hand so i can't say,

two If i were to build my own ELR rifle It would be set up for a minimum range of something like 1500 meters then everything would dial up from there.

A quick run of the numbers for a 408 w/ 400 gr doing 3000 FPS shows 10 mill high at 100 meters and zero at 1500 and 52 low at 3500 meters

10 mil high at 100 meters is not a bad compromise. and you could take a 19" string with a heavy ball hanging from it, use that as your point of aim and hit 39.3" above it.

I mean do you want a daily driver or do you want F1? cause you can't drive a F1 car to work you have to choose 100 meter zero within the usable range of the scope or just know that anything close is going to be a hold under.

[ShaunBrady]

Speaking as a complete rookie, 1 I would need to play with a Moab to see how repeatable it is. I'd be worried about slop and potential windage issues. but I've never had one in hand so i can say,

I bought one after my first URSA match and sent it straight back. With your background, I think you'll do the same.

Specific Complaints are:
The rail mount works by pinching the solid base piece rather than having a separate piece that pivots or slides to clamp the dovetail. I couldn't get the one I had to tighten on several of the rails I tried. Even if it had, that's not really the clamping action you want on a scope mount.
The tensioning screws are used for the rail recoil lugs. Those really should be square.
The front pivot was a threaded piece rather than a precision pin with a threaded end.
The elevation screw has play in the vertical direction.

It looks like airsoft level technology and is in no way a substitute for even a cheap scope erector mechanism.

I had to suffer through a mil spec speech and chase him around for awhile to get a refund, so ordering one to try wasn't without its overheads.

The windage issue isn't trivial either. Aside from spurious windage from loose or shifting components, getting it mounted so it tracks perfectly vertical or at least with the reticle is a trick that would be difficult to solve. You're stuck leveling your hold to the travel, you can't just rotate the scope in the rings to get it tracking vertical for the way you hold the gun. And that level is determined by the clocking of the mount screws. It's not something that is closely controlled during manufacture or easily adjusted.

Custom bases and 100+ moa vertical travel scopes are a better solution. Having the 100 yard zero is an advantage for development, but it doesn't need to be centered in the reticle if there are hashes above center. 100 moa of vertical travel isn't uncommon with decent 30mm scopes these days.

[kcstott]

I bought one after my first URSA match and sent it straight back. With your background, I think you'll do the same.

Specific Complaints are:
The rail mount works by pinching the solid base piece rather than having a separate piece that pivots or slides to clamp the dovetail. I couldn't get the one I had to tighten on several of the rails I tried. Even if it had, that's not really the clamping action you want on a scope mount.
The tensioning screws are used for the rail recoil lugs. Those really should be square.
The front pivot was a threaded piece rather than a precision pin with a threaded end.
The elevation screw has play in the vertical direction.

It looks like airsoft level technology and is in no way a substitute for even a cheap scope erector mechanism.

I had to suffer through a mil spec speech and chase him around for awhile to get a refund, so ordering one to try wasn't without its overheads.

The windage issue isn't trivial either. Aside from spurious windage from loose or shifting components, getting it mounted so it tracks perfectly vertical or at least with the reticle is a trick that would be difficult to solve. You're stuck leveling your hold to the travel, you can't just rotate the scope in the rings to get it tracking vertical for the way you hold the gun. And that level is determined by the clocking of the mount screws. It's not something that is closely controlled during manufacture or easily adjusted.

Custom bases and 100+ moa vertical travel scopes are a better solution. Having the 100 yard zero is an advantage for development, but it doesn't need to be centered in the reticle if there are hashes above center. 100 moa of vertical travel isn't uncommon with decent 30mm scopes these days.

Yeah that's what i was afraid of. I can do trig in my head and know that .001" variance over 4" is roughly 1 moa so this thing needs to be made like a Sine bar. and that takes a good amount of knowing WTF you're doing.

Something tells me i can make one better then i can buy
wouldn't be the first time.

[JMP]

For the OP, there are plenty of options for what you describe as most 34mm+ scopes will have 90 or more MOA of internal travel. You indicated 2,000 yards, which shouldn't be a problem if you have such a scope on a 45 MOA canted base. A scope as simple as a Vortex Razor 4.5-27x will get it down. If you want 2,500, 3,000, and further, then it becomes a lot more problematic.

[ShaunBrady]

Yeah that's what i was afraid of. I can do trig in my head and know that .001" variance over 4" is roughly 1 moa so this thing needs to be made like a Sine bar. and that takes a good amount of knowing WTF you're doing.

Something tells me i can make one better then i can buy
wouldn't be the first time.

The ERA mount is a multi sided sine bar.

I started down that track, but am mixing the ballistics into it now.

[LynnJr]

KCScott.
If you know the distances you will be shooting at you can have custom bases made in all dovetail design and just add what you need.
I understand what Shaun is saying about the front pin but most of us have already gone to heavier hardware and have solved that issue.
Put a Davidson base on your action with whatever hardware you feel is stout enough then add a 60 moa rail for 2000 yards a 85 moa rail for 2500 yards and a 120 moa rail for 3000 yards. The dovetail to dovetail bases run $75 each so you can get to 3000+ for $225.
The EraTac mount is more expensive and only has 70 moa in it. That will get a 338 Lapua to 2000 yards but it falls short at 2500.

[kcstott]

KCScott.
If you know the distances you will be shooting at you can have custom bases made in all dovetail design and just add what you need.
I understand what Shaun is saying about the front pin but most of us have already gone to heavier hardware and have solved that issue.
Put a Davidson base on your action with whatever hardware you feel is stout enough then add a 60 moa rail for 2000 yards a 85 moa rail for 2500 yards and a 120 moa rail for 3000 yards. The dovetail to dovetail bases run $75 each so you can get to 3000+ for $225.

And stack error too. No thanks. one base at a time, if it takes more range time so be it. but i'm not stacking bases like lego's. mil spec is just that, mil spec, meaning close enough is good enough. well not for me. If i'm paying $400 for a sine bar with a pic rail it better be ground in.

i make custom bases and rings, I just don't make Pic rail bases. stuff I make goes on African big game rifles. talley dove tails

so what with those bases? No recoil stops?

[DarkSoul]

On my Cheyatc I have a Leupold Mk8 (which has 90 MOA vertical adj) sitting on a 40 MOA rail with a 1 piece Spuhr mount (no cant). I am zeroed at 100 and can hold center at 2000. At 3000 I have to dial up almost to max the elevation and then hold over some 15-16 mils (if I recall) I would need to go get my DOPE book. Regardless, as was mentioned by many others, a scope with more elevation and a 40 MOA rail will be the ticket.

[JMP]

I use the ERA-TAC, not because of the adjustable design, rather they are one of the few makers of 36mm mounts and 70 MOA is right where I want to be with my scopes.

[kcstott]

Here's an example of what i make.



Rings too



And a Tactical style integral base for a 1" scope with built in 20 MOA machined from solid 7075. That is the only pic rail mount I've made