• Watch Out for Scammers!

    We've now added a color code for all accounts. Orange accounts are new members, Blue are full members, and Green are Supporters. If you get a message about a sale from an orange account, make sure you pay attention before sending any money!

ELR Scope, rail, mount specification calculation

FromMyColdDeadHand

40X Mafia
Full Member
Minuteman
Jun 19, 2008
696
669
CO
So I pulled a table for 22 out to 100 yards.
1618554984242.png

Realistically, and it sounds insane, I'd want a set up that would handle 550-600 yards max.

How do you calculate what mix of rails, mounts and scope adjustment needed for subsonic? I run MIL/MIL scopes.

So for 500-600yards, you'd need 30-40MILS/100-130MOA.

Scope mounts and rails would be additive, but when it comes to scopes, the internal adjustment is the total range that it will move. The zero you use will place the reticle in that range. The longer the zero range, the better the placement of the reticle?

So if you have a 30MOA base, a 20MOA mount is 50MOA or 14.5MIL. If your scope has 30MIL of vertical adjustment, does that mean that there is 15 (half) mils of elevation to use? So a total of 14.5+15, or about 30MILS of vertical to use That would get you close to 500 yards- and then you could go down the reticle to get more mils? at 25-30x on a scope, how many MILS of a reticle are visible 4-5?

BUt that is really using all the adjustment to get max range- your zero would be in a limited range of possible values? And if you had to dial in some wind, you might not be able to get the max elevation?

I've never had to play at the edges of the sighting systems before. I'm just looking for a way to calculate what is needed.
 
Yeah nothing there looks wrong so I'd say you are on the right track. If I was doing it from scratch I'd look at a 30 or 40 moa base if possible and a Era-tac adjustable mount now that they have a 0-20 mil model out. Simply to avoid maxing out elevation with whatever scope you choose.
 
With a 34mm scope in around 5-25 mag range with a centre fire you are looking at about 25MOA cant for zero so for a 22lr it's probably closer to 30MOA or more. For this application I would run a 60MOA rail with a 0-20MIL Eratac, this will put you safety inside the elevation range of a tactical style scope while giving you most of it's internal elevation range to play with on top of the 20MIL from the Eratac elevating mount. Depending on magnification and field of view 5 MIL or 6 is probably visible at max magnification on most of those style scopes.

So from 100 yard zero you would probably have 20MIL Eratac, 25ish MIL internal scope and 5 recticle hold or 10 if you wind off magnification for a total of 45-50ish MIL but this relies on getting a your rail angle correct for your zero to be near the bottom of scope elevation range.
 
I have two scopes set up for long range rimfire-

S&B 5-25: 28 moa rail allows all 26 mils of adjustment w/50y zero.

Kahles 624i: 40 moa rail allows only 22 of 26 mils if adjustment w/50y zero.

So, the advertised elevation adjustment varies by scope brand. S&B has more than the advertised 26 mils. An Era-Tac adjustable mount as mentioned is a solution to account for this variability, so you can in fact use all of a given scopes' elevation adjustment.

Obviously after dialing 26 or so mils of elevation, 5-15 mils of holdover would be necessary to get to 5-600y.
 
  • Like
Reactions: CBeck
What is ’overdoing it’? What would put a reasonable zero in jeapoardy?

Personally I'd say 60 moa rail is over doing it but it really depends on what scope you are going to use. 40 moa rail with 20 mil Era-tac mount with something like a S&B 5-25 PM2 will allow you to dial and shoot to almost 700 yards (obviously this is conditional.) while also allowing whatever zero you choose. Basically it should create a 0-700 yards .22lr setup.
 
And keep in mind that in addition to a rail, one can use Burris XTR Signature rings that has various incerts allowing one to set up to an additional 40 MOA.
 
Here are the details on my setup with my Vudoo

Trijicon Accupower FFP MIL 4.5-30 x 56
MPA BA Scope Mount, 0 MOA, 34MM 1.25" - able to dial 27 Mils with 40 MOA base

With Center-X at 1100 FPS. I was 30 Mils to 500 yds and had to hold over 3 Mils in the reticle which is not too bad of a holdover. I have a Charlie Tarac Micro on order that will give me another 30 mils which should be good to 750 yds (in theory)


 




Realistically, I'm running a scope with 25 mill adjustment and a 10 mill reticle, on a 20moa rail. I can just get to 500 maxing the dial and holding 7-8 mills.

If I changed to a 40moa rail I'd get a little more, but it's realistically running out of steam so quick I'm not going to bother. For 99% of my shooting I can simply hold in the reticle.
 
I was looking at the Charlie TARAC Micro, versus the Eratac mounts and decided to go with the Eratac mounts for my Vortex HDII. That should get me to about 500 yards. The TARAC is interesting, but gets expensive- but I can see that the ability to swap between rifles makes that a bit easier to swallow. But if I'm going to have to buy a mount for scopes anyways, the ERATAC ins't that much more expensive than a regular mount. I can see for really long range, the TARAC is the way to go.

That scope is on my CF bolt gun, and I just wanted to try the concept and might get another scope eventually.
 
I finally got in my Charlie Tarac Micro and it is awesome... nobody at the range knew what the hell that space looking box on the front was. Your drop table at the top is on for 400 - 20 Mils, 500 - 28 Mils, 600 - 37 Mils with Center-X. Below 400 looked a little strange to me, but maybe that is a 100 yd zero. 22LR is a fun round to try to stretch out.

IMG_3890.jpg
 
I finally got in my Charlie Tarac Micro and it is awesome... nobody at the range knew what the hell that space looking box on the front was. Your drop table at the top is on for 400 - 20 Mils, 500 - 28 Mils, 600 - 37 Mils with Center-X. Below 400 looked a little strange to me, but maybe that is a 100 yd zero. 22LR is a fun round to try to stretch out.

View attachment 7650905
So how does the micro work? I was reading their website and got confused. I though the micro had only one fixed come up?

You use a 100 yard zero? I guess that could work for a dedicated ELR22, but for a standard gun I'd like a 50yrd zero.

So your scope dials up to say 20Mils, how do you get to 20, 28 and 37. Get a micro set for 20MILS and then dial the scope to 0mils for 400 (for 20Mils total), 8 mils (for 28 total) and 17......

So you get a rail that gives your scope the most up to dial for long range, and then get the mirco set up for when the dialing stops. Then past that, add a micro set to around your max elevation, and then dial back to zero and have the add of the micro.

Can a micro be sent back to them to be 'reset'?
 
The micro is a simple, but perfectly calibrated tool - there are no moving parts, just 2 mirrors. You buy the micro set at a fixed angle, mine is 30 Mils which basically corresponds to my 500 yd data. The big charlie tarac is adjustable using some set screws, but the micro is fixed.

With a 50 yd zero, I have the ability to dial 27 mils which gets me to almost 500, so every distance before that I don't need the micro, I just dial. Starting at 500 and beyond I put the unit on the rail and it changes my 50 yd zero to essentially a 500 yd zero. Any distance past that I simply dial my scope just like you would normally. 600 yds, I dial 7 mils which is on top of the 30 the device gives me. So now with the unit I have 57 mils that I can use and not have to hold over in the reticle... 30 mils from the unit + 27 from dialing.
 
So 457 with the fast twist 1x9 barrel with a 20MOA rail and an ERETAC 0-20MIL scope adjustment, set at 20MIL. I got to the range and the gun shoots way high at 50 yrds. Vortex RAZOR scope and I adjust it all the way down. Much better, but still about 5MIL high. Take the ERATAC and dial from 20 to 15 and that seems to be a good 50yd zero- but I don't have any 'down' left.

So that means I have all of the Razor II HD vertical adjustment to play with PLUS 5 more MIL on the ERATEC.

So, in hindsight- the more opitmal set up would be to get as much onto the fixed rail as possible to keep the 50 yard zero and the ERATEC at 'zero' cant, and then be able to dial up the ERATEC mount 5-10-15-20MIL for longer range shooting.

So if I'm using 20MOA rail and 15MIL, I could use up to a 70MOA rail and then an ERATEC or TARAC to get the longer range. I wish the ERATEC was 0-10-20-30-40MIL.
 
Had same quandary but a bit loathed to bolt on more crap than needed to the rifle, just another thing to have kicking round in between times.

Went with the ERATEC in moa as that's the increments in the scope - the 22rf setup is a clone of my Dasher. Tested the ERATEC at 100 yards, put 40moa on and the change in impact was 41.75" and the back to zero so it's good re. repeatability. Does not add too much re. scope height on the rifle

Tried my first distance shoot on Sunday, 300 yards and very interesting. Both rifle and distance new to me so see a bit of a learning curve;

bisley 300.jpg