Rifle Scopes Elevation and canted rail question

[Whitshot]

Ok so I’m researching and I’ve got a couple simple questions. 1st when a scope is spec’d as having x elevation adjustment. That is total correct? So if I got an scope with 35mils of useable elevation, I’m going to be somewhere in the middle of that 35, for my 100 yard zero. Correct?

If that’s so, what’s your best guess as to where?15up and 20 down? I’m trying to figure out how much rail and ring/mount can’t I want. I assume you don’t want so much cant that you almost bottom out the turret? I will still spend a lot of time between 0-8mils on this rifle. Although I’ve had to hold over past 1600 yds because I’m bottomed out at 19mils (swfa 5-20 with 20moa rail)

Thanks

 

[diverdon]

That is the reason why we buy inclined rails and or one piece mounts with inclination built in.

Choose your flavor 0 MOA 20 MOA or 40 MOA, one of the above should get you a 100 yard zero with most of your adjustment still available.

 

[Engineer260]

If that’s so, what’s your best guess as to where?15up and 20 down?

should be split half up and half down as long as zeroing doesn't take much.

if the 0 MOA isn't giving you enough adjustment, the 20 MOA or 40 MOA scope base or scope mount will get you what you need as @diverdon recommended.

 

[Glassaholic]

OP, as a general rule you can go up to half the MOA of the total travel of the scope. So if your scope offers 80moa total travel then theoretically you can go up to 40moa of cant; however, I say theoretically because not all scopes are created equal and some don't do well when bottomed out. The "happy" compromise is typically 20moa, but if you're maxing that out with some shots at 1600yds then you'll either need a different rail offering more cant or get a mount that offers cant to double up with the rail cant - so a 20moa rail plus a 20moa mount equals 40moa of total cant which will max out your 80moa scope. Granted, if your scope does more than 80moa then you're golden.

 

[TheOE800]

The "happy" compromise is typically 20moa, but if you're maxing that out with some shots at 1600yds then you'll either need a different rail offering more cant or get a mount that offers cant to double up with the rail cant - so a 20moa rail plus a 20moa mount equals 40moa of total cant which will max out your 80moa scope. Granted, if your scope does more than 80moa then you're golden.

All of my scopes have ~27 mils or more of travel, but I typically stick with 20 MOA of slope. How many of us typically fire that far on a continuous basis to need that much? We’re shooting some pretty flat cartridges these days. My issue is being at the bottom of erector travel, you’ve got quite a ways to go to optical center where image is optimal. I’m sure there’s nothing wrong with my Minox at the far ends of adjustment, but when shooting to 1000 yards is most of my time, why worry when that’s only going to take 8 mils of adjustment?

The S&B literature recommends 40 MOA of slope to get all the elevation adjustment possible out of their 5-25x56 PM II for instance, so they must be pretty damn sure their product is fine at the ends of adjustment...but it seems unnecessary if you’re not reaching out a mile or further.

 

[Whitshot]

All of my scopes have ~27 mils or more of travel, but I typically stick with 20 MOA of slope. How many of us typically fire that far on a continuous basis to need that much? We’re shooting some pretty flat cartridges these days. My issue is being at the bottom of erector travel, you’ve got quite a ways to go to optical center where image is optimal. I’m sure there’s nothing wrong with my Minox at the far ends of adjustment, but when shooting to 1000 yards is most of my time, why worry when that’s only going to take 8 mils of adjustment?

The S&B literature recommends 40 MOA of slope to get all the elevation adjustment possible out of their 5-25x56 PM II for instance, so they must be pretty damn sure their product is fine at the ends of adjustment...but it seems unnecessary if you’re not reaching out a mile or further.

Understood, thanks for the replies. I should have included my current rig:

RPR with factory 20moa rail
JP 0moa mount
SWFA 5-20 HD with 30mils of elv spec

So this setup is not getting me past a mile. I've shot 1675 and had to hold over. Your point's are all well taken. I think your right, it's better to have the lenses more centered in the tube. However I'd like to be able to shoot everything I would like to say 1800 yards without having to hold over. I'm curious now where I'm at on my setup. I should just dial down and figure out how far up I am at 0.

It's making sense. Thanks guys

 

[TheOE800]

If you were zeroed at perfect optical center you’d have ~21 mils of upward elevation adjustment (30/2 = 15 + ~6 = ~21) in the turret with just the RPR rail. A 20 MOA mount (40 MOA total) would get you another ~6 mils before needing the reticle.

 

[Gunfighter14e2]

Ok so I’m researching and I’ve got a couple simple questions. 1st when a scope is spec’d as having x elevation adjustment. That is total correct? So if I got an scope with 35mils of useable elevation, I’m going to be somewhere in the middle of that 35, for my 100 yard zero. Correct?

If that’s so, what’s your best guess as to where?15up and 20 down? I’m trying to figure out how much rail and ring/mount can’t I want. I assume you don’t want so much cant that you almost bottom out the turret? I will still spend a lot of time between 0-8mils on this rifle. Although I’ve had to hold over past 1600 yds because I’m bottomed out at 19mils (swfa 5-20 with 20moa rail)

Thanks

In a perfect world if you have 35mills of total, in the scope, an if the barrel is clocked perfect, an if the base an rings are in perfect alignment with the barrel, then you subtract your drop to 100yds,then the way it was explained is correct. However I've never seen a perfect set up no matter who built it. Remember as you bottom out the erector you have very little windage adjustment. So based up on all the factors you need to be careful when choosing your rings an base set up. Just FYI if your shooting a 308 you need about 4 minutes of up just to get to 100yds based upon the std mechanical off set for a 40-50mm objective over the bore. Other calibers take a little more an others slightly less.