Rifle Scopes SMOA/IPHY vs MOA

[dpilot83]

In my searching on this forum I've seen lots of threads about MIL/MIL vs MOA/MOA and I've seen descriptions of MOA vs SMOA or IPHY but I really haven't seen any MOA/MOA vs SMOA/SMOA threads.

I feel like because of my reading I pretty clearly understand the differences between the three. Based upon what I've read I'm primarily attracted to MOA because I only have to visualize dividing a MOA into 4 rather than having to visualize dividing a MIL into 10.

For some reason I used to be really opposed to SMOA or IPHY but as long as you can get the turret and reticle to match on that, theoretically it would be even easier to do the mental calculations with SMOA or IPHY than it would be to do the calculations with MOA or MIL as far as I can tell. Am I wrong on this? If not, why is SMOA or IPHY not more common? Thanks.

 

[Bedlam]

Re: SMOA/IPHY vs MOA

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dpilot83</div><div class="ubbcode-body">Am I wrong on this? If not, why is SMOA or IPHY not more common?</div></div>

No, you are correct. Early standards have inertia that is difficult to overcome with later standards, even if the later standards are superior.

It's same reason why the US still isn't metric and why the UK, although officially metric, still uses miles, gallons, stone, pints, pounds, and ounces. (It makes me wonder how they can even call themselves a metric country.)

 

[BigJimFish]

Re: SMOA/IPHY vs MOA

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">If not, why is SMOA or IPHY not more common? Thanks.</div></div>

I think that the best answer to this is that most of the people who know that the IPHY equations are as easy as the mil equations and that true MOA equations are a pain are using mils themselves.

Maybe this is because the scope they wanted was available in mils, they received mil training from the military or they just figured that mil stuff was more popular and that you might as well learn the more common system. It has probably been all three reasons to a good degree and more besides. I use a IPHY USO and I'll admit I don't think I would go with something in true MOA's. I'd sooner just switch to mil. Given the prevalence of it, I'll probably switch at some time anyway even though I range better in inches and feet than meters.

 

[jakelly]

Re: SMOA/IPHY vs MOA

Yeah these are the future in the American market. The benefits of both systems for an American mind. I just switched everything to mil/mil configuration. Now I laugh at myself because I stubbornly resist changing my LRF to meters instead of yards, which by all accounts I should. The mil system is a metric creation and works best there. My own reluctance assures me that I haven't switched for the last time, and I think the US market will again, too.

 

[sandwarrior]

Re: SMOA/IPHY vs MOA

First, I had to remind myself what SMOA was. Shooter's MOA or Inch per hundred yards.

IMO, there isn't a whole lot of difference in any of the systems as long as the turrets match the reticle and come-ups/hold values.

Nothing worse than dialing up then having to mathematically figure the error.

For ranging out to 1k you'll note there is only .47" difference in moa vs. iphy/smoa. But when you start dialing it, that 5% difference really adds up. To the tune of 16-20" @ 1000 yds., depending on what round you are shooting.

So if your calculations are in mils and you dial up in mils with no error, just follow the numbers and hit it. Same with iphy and same with moa.

The only issue I can see is with iphy, you don't start with a relatively rounded number as far as angular measurement. That's if you have to start completely from the beginning. In moa it's 1/60 => sin => x 3600(inches in 100 yds) But, if shooting metric you then need to convert metric to yds. And that is a pain in itself all over again (military maps are metric...sometimes we have to range that way).

ADDED:

This still goes back to the old axiom stated here time and again. Whatever system you have, get behind your scope and work with it, or it will be like cooking with your feet. It won't work so well.

 

[jakelly]

Re: SMOA/IPHY vs MOA

The millirad is a metric creation you can learn the history here. The millirad unit represents ten cm or one decimeter @ 100 meters. The Europeans redesignated the circle based upon trigonometry not the traditional degrees and minutes. The standard system uses 100 units divided by 3rds made up themselves of 12ths broken down further into 4ths or more commonly 16ths. The metric system uses all tenths. No you don't need to use the metric system to use mils but it simplifies the math. And no, I don't think it would have caught on so well outside of a tenths based system.

 

[Graham]

Re: SMOA/IPHY vs MOA

IPHY is very common. It's just that many scope users have no idea that they are in fact using IPHY when they dial.

 

[jakelly]

Re: SMOA/IPHY vs MOA

Graham,

Are there any IPHY reticles available?

 

[dpilot83]

Re: SMOA/IPHY vs MOA

USO's PC MOA reticle is IPHY.

 

[E. Bryant]

Re: SMOA/IPHY vs MOA

Just a quick note - radians (and divisions thereof) are not "metric" or "European". They have their roots in the physical laws of nature.

 

[scudzuki]

Re: SMOA/IPHY vs MOA

Distance calculation in mils is so f&*^ing easy.

height of target in (your units) x 1000 / apparent size in mils = distance to target in your units.

This can also be expressed as height / apparent size in mils x 1000.

What could be easier than that?

It IS NOT metric; it is decimal (base 10) which makes it super easy to do the math... divide then move the decimal point.

I do it like this;
2 yard target (a man) is 3 mils tall = 2/3 or .666, move the decimal point 3 places, 666 yards.

Joe

 

[jakelly]

Re: SMOA/IPHY vs MOA

I understand that, but the choice to divide by the radian by 1000 and form the milliradian was made by men educated in and familiar to the metric system. I don't want to raise tempers, but there is some logic to the history that will help us understand our practices today.

It would have been more convenient for the US to divide the radian by 100 to correlate directly to yards, 300 and correspond directly with feet, or even 3600 and conveniently equate to one inch at 100 yds. Then, all of the European countries would be doing an extra conversion step.

The tenth of a mil is .36" per 100 yds for you, and 1 cm per 100 meters for the European. Who do you think divided that radian?

The system was developed to help artillery fighting on metric maps with metric minds. If anyone hates the thought of using a metric scope you can move the decimal point one spot to the left and write yds over mils.

 

[Graham]

Re: SMOA/IPHY vs MOA

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jakelly</div><div class="ubbcode-body">The millirad is a metric creation... The millirad unit represents ten cm or one decimeter @ 100 meters.</div></div>Milliradians and MOA are both measurements of angles. Neither has anything at all to do with any system of linear measurement. A milliradian is an angle which subtends an arc whose length is one-thousandth of the distance from the vertex of the angle. It does not matter what that distance is measured in - inches, feet, yards, miles, millimeters, decimeters, centimeters, meters, or attoparsecs. At a distance of 1000 attoparsecs, the length of that arc is one attoparsec. So, milliradian is a term which is not metric. Sorry about that.

 

[sandwarrior]

Re: SMOA/IPHY vs MOA

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: E. Bryant</div><div class="ubbcode-body">Just a quick note - radians (and divisions thereof) are not "metric" or "European". They have their roots in the physical laws of <span style="text-decoration: line-through">nature</span> <span style="font-weight: bold">planar geometry/trigonometry</span>.</div></div>

Fixed it for you...

Added:

It was Cotes (an English mathematician) who started using the "radius of a circle" as a more natural source to measure other features of the circle. Since the ratios were always the same, it always gave the root source of measurement. The 'radian' is the actual arc distance equal to the radius of that circle. Just like perpendicular bisecting diameter chords of a circle the radian always gives a true angle. The circle is then broken into radians (6.28~something). When a distance is applied the radian can give a height. The reverse order of that mathematical sentence can take a height and with a known {fraction} radian (the milradian), a distance can be determined.

The whole point of my rant is that radians were being used before "metrics" were formalized. And, no matter what units are used to measure different pieces of the circle, the ratios are always the same.

 

[jakelly]

Re: SMOA/IPHY vs MOA

Well fellas I respectfully disagree. I won't repackage my arguements again.

To the OP, yes, IPHY can be simple and accurate because you are probably more accurate using inches in terms of guessing the size of an object than any thing else. No matter what ratio the subtensions to distance formula uses, the ability of the system to range an object accurately will depend on your ability to estimate the size of the object in your value with accuracy and your ability to estimate the amount of subtension(s) the object of "known" size occupies. With IPHY you estimate in inches and get hundreds of yards for distance, pretty precise and simple if you're accustomed to the US system. I think there is tactical/practical utility knowing the size of many everyday objects in inches when using IPHY. A 2x4 is 3.5 inches wide by 1.5 thick, a truck rim is 16", stairs are 7" tall, or a stop sign is 30" wide can all help you get a more accurate range. With mils whatever increments you want in distance you need to use for size estimation, or do the conversion math which in the US system isn't that easy.

When we as a shooting community understand that we can choose an angle that subtends a ratio that works well within our current distance formula you will see debates about IPHY vs Mils. One of the foundation stones of that inquisition is recognizing that the milli portion of the radian was devised from and works best within the metric system. So we are still a little removed from that point.

 

[para1505]

Re: SMOA/IPHY vs MOA

I just love math class

 

[Bedlam]

Re: SMOA/IPHY vs MOA

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">but I really haven't seen any MOA/MOA vs SMOA/SMOA threads.</div></div>
All you people arguing about MILs, did you even notice the OP asked about MOA and SMOA? Thanks for making this <span style="font-style: italic">yet another thread about MIL</span>.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body">IPHY is very common. It's just that many scope users have no idea that they are in fact using IPHY when they dial.</div></div>
Very common? Really? Leupold, Nightforce, Swarovski, Vortex, and SWFA all use true MOA.

USO does IPHY. I'm not aware of anyone else using IPHY, but I'd love to know who does. For something that's very common I sure have a hard time finding it.