Sunday, March 13, 2016

Making a Fixed Parallax Scope Work for CMP/NRA Highpower

Updated:  23-March-2016

The CMP's 2016 Rule 6.1.1 allows for the use of optically sighted M-16/AR-15 rifles in service rifle competition.  The optics used must be commercially manufactured not exceeding 4.5X magnification.  While this specification allows for future improvements to equipment designs by the industry, early adopting competitors are limited in their choices.

Utopia vs. Reality

The ideal scope for the game per the 2016 rule would be a 1-4.5X scope with impeccably repeatable and exactly tracking 1/4 MOA turrets coupled with objective parallax adjustment and a Euro-style finger adjustable fine focus at the ocular that can stand up to thousands of rounds per year of firing cycles.  At present, only one commercially manufactured scope meets these criteria; it also costs more than the rifle.  All remaining commercially manufactured scopes are fixed parallax articles.  Within the fixed parallax field, some -but not all - higher priced commercial models provide the desired level of turret repeatability; that is, equal to the utterly solid performance of a competition 1/4x1/4 pinned A2 rear sight.  At the lowest price points, robustness becomes an issue.  Most of these name or store branded scopes are actually manufactured by wholesaler OEM's.  They were designed around light recreational use engineering specifications; a universe vastly different from the pounding competitors place on their equipment.  What may work for the shooter coming out to shoot half a dozen CMP 200-yard Games matches a year may not last through the early-season work up for someone pursuing distinguished or more.

My assessment of the present imperfection in available commercially manufactured optics options is that it is likely to persist.  When I was at the 2016 SHOT Show, I made a special effort to visit the scope makers - as did others - inquiring about currently available scope models and, more importantly, their appetite to invest in new models to address the highpower competition market.   The answers were discouraging.  Firstly, the highpower market is a small specialized use case, make that minuscule in terms of the return on investment mathematics; the scaling potential just isn't there for convincing companies to allocate precious research dollars.  Second, the engineering required to package an idealized scope is not trivial.  Most 1-4x optics on the market have 1/2 MOA or 2/10th's MIL click steps.  The reason is because the fineness of the threads necessary to accomplish the precision tracking to 1/4 MOA in a 4X and lower magnification optic delves into new areas of aerospace class micromachining technology.  The tech exists to be sure but getting it to the firing line is what the MBA in me would call a non-trivial capital investment decision. Third, the 2016 CMP Rule capping maximum magnification at 4.5X runs counter to where the much larger 3-gun and military trends in day optical requirements are headed.  As 3-gun matches continue to increase the degree of difficulty to keep pace with the skills exhibited by top competitors, some of whom also shoot in precision rifle matches, the desired maximum magnification range in these optics shifts to the 6 to 8 power range.  Similarly, more emphasis on engagement at distance by the military, extending soldier systems into the 600-800 meter range, also pushes answers to a 6 to 8 power range optical solution. Given these factors, my belief is that highpower competitors will have to cope with existing commercial offerings for some time.

So be it; so the equipment isn't perfect; it's still usable.  The mission becomes to figure out how to drive what we have to get the most out of it.

Regardless, I believe that for bringing in shooters new to highpower, a scoped service rifle is the new fastest path to an NRA Expert classification card.  At the club level, bring that 3-gun "tacticool" looking machine with its muzzle brake or that 16-inch 1-9 twist AR whatever carbine you bought in the last gun control panic with the cheapie optic you got with it. Any optic will work.  Every shooter will benefit.  Shoot 100-yd Reduced NRA matches until you earn Expert.  You'll learn loads about improving your marksmanship fundamentals that will pay off in confidence and competitiveness in whatever other discipline you shoot.  Most people skip over this fundamental building block when first getting into shooting.  The CMP's 2016 rule innovation, with reasonable leeway by club match directors, opens the door for many, many people to pick up this essential building block without having to invest in any new equipment.  I'd encourage the entire shooting community to take a crack at it.

With that, here are my personal driving notes so far on using scopes on top of a service rifle,

Slow Fire Offhand 

Really, really, really trust your wobble.  Don't bother to dial your optic down to 1 power for offhand.  For all intents and purposes, a fixed 4X scope is probably just as good for this game.  After some experimenting, I found that keeping the scope at 4X and focusing on the reticle is what works for me.  The target will wiggle around as you wobble.  That wobble was always there even with iron sights; you just could not see it before and it's plain as day to see now.  It's like having one of those really expensive SCATT trainers the smallbore/Olympic guys use to train to reduce their wobble except, there it is, giggling at you in offhand.  Don't let the fact that you can see it now phase you.  Just focus on the reticle, relax into minimal movement as you let your NPA (natural point of aim) do the work of centering things up, squeeze with the best trigger discipline you can muster and crack it when your "chi" says TEN!  The results are delightful when it comes together and instructive when they don't.  Tickle yourself with this, an X in a highpower SR target is like hitting the letter A embossed in the A zone one or two football fields away ... standing.

Rapid Fire Sitting and Prone

This is where these scope truly shine in my opinion.  The full distances of 200 and 300 yards are well within the envelope of the factory pre-set parallax of most - if not all - scopes on the market regardless of price.  Turret movement to go from 200 to 300, if you choose to dial for it is 2 to 3 minutes - 4 to 6 clicks with a 1/2 MOA scope - at most depending on what ammo you are using so there are no issues with tracking accuracy.  Again, focus on the reticle not the target.  This actually requires mental discipline particularly with higher grade optics because the target looks so pretty in the image.  Ignore it.  This is instrument flying.  Keep your eye on the gauges.  There are some advantages with an optic.  You are impervious to light changes on the target; just hold center.  You can see coming to center as you breathe between shots better too.  With 4X magnification, if you had the discipline, you could shade for wind driving the reticle within the target's center; but if you have good repeatable turrets, dial the wind at 300 the same way you would your A2 sights. Just remember that those scope turrets turn opposite to how all U.S. service rifle sight knobs turn.  Irons drive like steering wheels; turn left to move left, right to move right.  Scopes are like bottle caps; screw in to move left, unscrew to move right.   Please remember to laugh at yourself every time you turn the wrong way at a match until you get the hang of it.  It's part of the apprenticeship process to fire a perfect tight group into the 7 ring because you dialed the wrong way.  Welcome to highpower!

600 Yards

Yeah, parallax is a problem.  The scope makers can talk about the minimal effects of optical specifications all they want but the fact of the matter is that shooter variables such as head position behind the eye box of a scope with an objective lens 500 yards out of alignment means a shooter has a lot more to get right every shot than an iron sights gunner at 600 yards.  Where the A2 shooter has the advantage of a two point of reference sighting system to manage sight alignment  - remember that being one of the axioms of making a good shot in the "litany of fear" drilled into all of us? - the scope shooter has only the single plane of the optic.  This is why parallax adjustment is so important as any smallbore, midrange or long range shooter knows.  You need to get the parallax matched to the distance to make the ocular eye box more tolerant of eye placement errors behind the optic.  If the parralax setting is off, get the position ever so slightly wrong and even the best shooters on the planet will fire corner pocket 7's and 8's at 600.

Sight Alignment

But, there are no reasonably priced 1-4X tubes with objective parallax on the market.  What to do?  The answer might be to create a sight alignment method for fixed parallax optics.  Huh?  This flies in the face of how you want to set up a "combat" optic on a gun for speed and ease of use but bear with me and ponder this.

Consider mounting the optic not at full eye relief to see a perfectly clear picture when mounting the scope but a little closer to your eye so that in prone there will be a shadow that forms if you are not perfectly centered behind the optic.  Center up to manage the shadow kind of the same way you'd keep rings of white with an aperture sight.  Voila!  Sight alignment!

Note that 600 yards slow prone is the only position you "need" this for.  Your head will be tilted a little bit more forward in prone than in standing or sitting.  If you have a collapsible butt stock, using one of the shorter length of pull notches might do the trick to get you in the zone if the standard A2 rear stock doesn't suffice.  The MagPul UBR has screw in pre-sets; might be handy for this.  You can get more rear weight in the A2 butt though and that may or may not be a consideration to you now that the 11.5 pound weight limit thing is no more.

If you use the same rifle for 3-gun, you want - make that need - a full eye relief placement of the optic when you mount the gun rapidly in that discipline.  A quick detaching base where you can reposition the scope a notch or two back for highpower shooting may be your salvation to create a dual-purpose "crossover" gun.  The best ones on the market go on and off quite well.  Probably best to use a zero degree mount so you don't induce angular shifts when moving fore and aft on the receiver rail.  Remember you are still working within the very short baseline of sight axis to bore axis and tiny changes mean boatloads down range.  Less is more.

Is this a perfect engineering solution?  No, it's coping with what we've got.  But if it works for you ... hammer it!  Nothing says we cannot use innovations in technique to overcome equipment limitations until something better comes along.  We're Americans; that's what we do.

Update on 23-March-2016

Reports are beginning to come back that the "sight alignment" trick works with fixed parallax scopes to get the gear to work at 600 yards slow prone.  People are moving both closer to and further away from the scope eyepieces to create the shadow that they are using to create their alignment halos.  Observing people on the line, it looks to me to be around 1/2" of movement different from where they say they normally place their heads on an A2.

All the people I have personally observed so far move their heads.  One person I talked to told me they intended to keep their body in the same spot and move the scope base forward of backward on the picatinny rail.  I suspect more people will to this later on after they become comfortable with how they want to shoot the halo.  One late addition to the sight alignment came in on the morning of the 24th.  This shooter says he drilled a 1/8th inch hole in the scope cap.  I hadn't thought of that one.

This finding is significant.  It means that any scope that has decent glass and repeatable turrets can be made to work for highpower service rifle competition.  This opens up a much broader selection of optics that can get people on the line.  This finding is also significant in that it verifies that a scope with objective parallax adjustment will indeed be much more forgiving of head position movement.  This will probably be an equipment separator in the future that could make a difference in what works easiest to win.


This article is a work in progress.  The incorporation of any new technology into a competitive environment always takes learning curves in unanticipated directions.  When I first heard of this pending rule in 2015, what intrigued me most was to see where it would go.  As I learn more, I'll continue to chronicle.  This story to me is the next chapter in a long book of service rifles that comes after the one headlined, "'Matty Mattel' Pop Gun Displaces Thundering Herd of NM M-1's and M-14's".


Unknown said...

I have been told by a tech at one scope company that at 4X, if parallax is set for 100 yards, that at 600 yards, the error at most is less than 1/2 MOA. Adjustable parallax was only important as scope power got higher.

Can you find any "truth" to this claim. I would assume there is math somewhere that would tell us exactly what error there would be....

Dennis Santiago said...

It is indeed true that the mathematical parallax error of the optic is minimal. The problem I've observed watching people shoot with optics is that this manufacturers computation presumes an identical fixed position of the human eye at all times. In real world shooting this simply is not true. Our heads will move around the eye box of the scope as we shoot. When you add this human element to the equation, it amplifies the error. This is exactly why scopes have parallax adjustment. It's true purpose is to create a more forgiving eye box zone behind the scope so it is more tolerant to real world position shifts by the monkey behind the glass. If you will notice, the "fixes" proposed in the article do the same thing; they help you keep your head and eye in the same spot.

Unknown said...


So with all the warts aside, Vortex or Luepold? March and Nightforce out of the picture. I have heard pros and cons of each, best of the worse is what I am looking for. Thanks.

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That is why scopes have got parallax adjusting. It really is correct goal will be to make a a lot more forgiving vision package zoom powering the particular opportunity therefore it is a lot more tolerant to be able to real-world place adjustments from the monkey powering the particular goblet. When you will see, the particular "fixes" offered inside the write-up carry out a similar thing; they will allow you to maintain your brain and also vision inside the identical area.

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Dennis Santiago said...

M. Cieslewicz,
Honestly for across-the-course anything with a repeatable turret seems to work. You're going to adjust your shooting position to get your eye behind your optic. It may take a few iterations to get comfortable with something different from your irons gun position but it'll get there and your notebook will reflect the differences in set up that work for you. That being said, people seem to drive fine with Vortex's. There are reports of turret hysteresis with some Leupolds but just as many people reporting they dial fine; it may very well be people still in transition with learning to adjust positions to get behind the glass. At the low price end Iron Sight Inc. has updated Weaver K-4's with MicroTrac turrets from Weaver T's in them. Repeatability doesn't get much better than a MicroTrac. Jim Owens also has a solution he's offering with the scope and mount bundled. The ISI and Owens are $350-$400 price point options. At the high end, it's still Nightforce versus March. I like NF 4.5X SR I'm testing so far. I used it at Perry for NRA week and it gave me 26 NRA points for my trouble.

Dennis Santiago said...

Yes having a scope with adjustable parallax eases the eyebox positioning problem. That's the attraction of the March 1-4X. Texas did very well with them at Camp Perry but the crowd shooting fixed parallax scopes and the 200-yard focused NightForces did just as well. After Perry 2016, adjustable parallax seems like a nice to have but it may not be perceived to be as mission critical an argument point as it was before nationals.

Dennis Santiago said...

Dude is that some sort of advertisement for equipment options that have nothing to do with highpower competition? None of the items discussed in the link you provided have one iota of utility to shooting XTC matches

Unknown said...


In the type of scope you would use for Service Rifle competition (one that meets current rules), when properly collimated you could expect the scope to have an aim point error of 0.15" @200yds, 0" @300yds and 0.47" @600yds. These numbers are based on a competitor moving his eye all the way to the black edge of the exit pupil; just about to where you couldn't see the image and make the shot. In other words, these aim point error numbers above are highly unlikely. I'm struggling to see why you would benefit from adjustable parallax on a scope with such low mag and small objective.

Unknown said...

Regarding the 1/8" hole drilled in scope cap: I am new to optics and bought the NightForce fixed 4.5x I did see someone with hole drilled in front cap but did not notice the rear cap--- hole in front, or both ?,Thx

Dennis Santiago said...

Personally, I'm not really sure what a small hole in the front does for one's shooting. One of the big advantages of a scope is that its light gathering power makes you light conditions insensitive. You can shoot from glaring sun to the dim light of dusk at the end of a long match and have a good sight picture. Reducing the size of the objective light gathering area seems counterproductive to this advantage. The hole in the back is for making it easier for you to consistently place you eye in the same position each time which aids better sight alignment. This is particularly important for scopes that are mounted on rings above the ideal height of 1.300" above rail height where cheek well consistency is easiest to feel. Above that height and the shape or most people's faces leads to "bobble heading" where having an additional aid to assist in consistent eye placement behind the optic should have a positive effect on points. Caps are cheap and you can experiment using black tape to see what works for you but I'd go with rear myself. The bottom line is do what gets you the most points.

Dennis Santiago said...

Jack Lapham,
I am increasingly convinced that adjustable parallax is superfluous compared to consistent head placement behind the optic coupled with learning the discipline to focus on the reticle and not through it at the target.

Unknown said...
This comment has been removed by the author.
Unknown said...

L am waiting until someone comes out with an adjustable parallax !!!!!!!!!

Unknown said...

I'm struggling to see why you would benefit from adjustable parallax on a scope with such low mag and small objective. best ar scope

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