Thoughts on Optic Bias

[win&legend]

I often hear people say the bias of the optic does not affect the accuracy, even including the optics manufacturers. This is only partially true. It does not affect technical precision or accuracy, but it does affect practical accuracy. Below is an illustration which clearly shows the reality of the physics of the placement. For reference, I am defining Technical accuracy as something that is independent of the user / operator's ability such as bore precision, cartridge consistency etc. where piratical accuracy is what affects how a human interacts with and takes advantage of the technical abilities of the fire arm.

35724

I did some searching, spent a couple of hours really, looking for photos of Army Special Forces and other various elite units, I noticed there was a common but not universal theme, almost all of them had a rear biased mounting position of their optics, not forward / scout, which to me suggests they are geared towards close quarters. Speed and endurance are the two advantages to a rearward mounting position. The disadvantage is precision as the same motion of the muzzle results in less detectable movement of the reticle by your eye, making precision shots at longer ranges more difficult. I've used both positions and confirmed this reality, but I'm torn between loosing that longer range precision vs the speed and endurance gains. I'm interested in everyone thoughts and even real world experiences of veterans on the practicality of one other the other and what level of precision one would typically really need. The application is a defensive rifle, the environment is urban country (sprawling urban neighborhoods, a 1950's country suburb, right on the edge of vast open farm fields).

I think it's quite apparent you can't have your cake and eat it too so to speak. There are trade off's with either position. Also for reference, when I say scout position of the optic, I am referring to a forward bias such that the entire optic (an EOTech 512) is centered between the front of the receiver and the back of the gas block, meaning the optic is entirely on the rail and not the reciever. By rearward bias, I mean the hood of the optic is centered over the mag well or just just slightly back of the mag well. Thanks all.

[Eurodriver]

Hell of a 15th post! I'll be watching this with interest. Good stuff.

[sua175]

Since you want the input from a veteran I will give it. I think you are over thinking in your analysis.

First, the majority of guys in SOF units do not mount their optics forward of the upper receiver for two main reasons.

first, it is commonly felt that the actual receiver is a more stable platform than a bolted on rail that has the potential to shift or move and thus affecting the zero of your optics.

Second is that the rail is used for auxiliary equipment such as lights, lasers, leaf sights, so not a lot of rooms for optics, not to mention making the weapon front heavy.

Now when talking about non magnified optics such as a eotech or aim point, I as well as most guys prefer to mount then as far forward on the receiver as possible.


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[Failure2Stop]

As pointed out above, mounting the optic to the handguard of a rifle that does not have the handguard as an integral part of the receiver reduces the precision of the optic for a few reasons, and can show POI shift with different pressure applied to the handguard.
Most folks place optics on the upper receiver because it is the most rigid place to put them.
Aimpoints and EoTechs tended to migrate forward to the front of the upper receiver, and even further out with cantilevered mounts, to permit getting a magnifier behind them.

[TAZ]

I am no High Speed Low Drag kind of guy so YMMV on my opinion. Folks mount optics to receivers many cause they are the most rigid and stable items available. On bolt rifles you had the barrel or the receiver. Between those two the receiver is the obvious choice. Plus you don't get the goofy harmonics issues with hanging odd weights of a barrel. Jump forward to the AR platform and you have the receiver and the snap on hand guards. Not much choice there. Heck even most free float tubes aren't designed for precision optics mounting. Id bet if you asked some high dollar hand guard engineers they's tell you you're better off mounting to the receiver. Far more rigid, far better control over concentricity to the bore and far more consistency. And in long range shooting consistency is king.

WRT shooting, Ive shot Scout rifles, Red dots and decision optics (standard mounting) and my experiences are the opposite. The further out the scope the faster I was on target, but I was far more accurate with standard optics mounting locations. Its not a fair comparison, as the scout was a 4x and the precision was 10x or 22x. Definitely NOT apples to apples. Personally, at range I had no issue with noticing my heart beat move the reticle about. I also wonder what the physics behind making something like a 22x scout the scope would be.

As for your dilemma of a defensive rifle in urban sprawl; the question to be answered is what are your goals. Minute of man or making head shots at ranges past Ft. Dix? If you're talking plane jane defense then a red dot with a magnifier for target ID or a low power variable should work fine. Best thing to do IMO is figure out what you will realistically need to accomplish using todays equipment and then go about making that happen. Understand that you'll make compromises to attain your goals. You won't have a sniper rifle be effective at CQB nor will you have an SBR be a sniper rifle. Also understand that technology changes and in a few years you may be able to make changes that will shrink the compromise window a bit.

[win&legend]

Thanks for the input everyone. One point I did not mention but had pondered was POI shift, but the Samson rail I have on there is very secure, it would take one heck of a knock to shift it, but it's certainly in the realm of possible. What I liked about the optic being mounted on the rail was how naturally I felt the rifle pointed (in terms of reticle movement relative to my arm movement). I agree, it did seem faster on target, but also seemed more accurate because I could detect muzzle movement more easily (see image above) having not so great eye sight. Going back to the POI shift, I did encounter one very strange problem during a V-tac drill, I couldn't hit a thing until I realized I was flexing the barrel or rail, I couldn't tell which was flexing but I'd guess the rail given the barrel is a reasonably hefty gov profile, so that may very well have been the issue (I originally suspected a loose barrel nut but found that wasn't the cause).

After having tested the scout position out with a plate carrier and armor I found what was mentioned about front heavy to be the case. Technically the rifle isn't front heavy, it's balance point is right at the front of the mag well which is about mid length on the overall rifle, I can literally balance it on a fine edge, but the reality is that we want more of the weight to be concentrated in the rear which facilitates ease of use (like a bull pup), especially when it comes to endurance. I had read an army study (1997) proving at the very least that keeping the mass of the rifle closer in to the body (they were experimenting with shorter butt stocks) facilitated less muzzle movement, this was more dramatic the longer the time frame as fatigue significantly increased the muzzle movement off target.

I can confirm that after having run some box drills, that my support arm (shoulder and back) became fatigued very quickly having to drive that extra 3/4 lbs that far out, which is much more cumbersome and difficult when wearing armor, even with a good plate carrier like a Crye JPC and 5 lb ceramics. As I became more exhausted it just became that much more difficult to keep the rifle on target regardless of how naturally it did or did not point. All of the sudden I didn't care for the scout position so much and was wishing for something less "cumbersome"! It's quite a amazing at how often an idea may seem plausible and practical in the mind's eye yet the application of it so often proves the fiction of it. Here's a photo of SF training Hungarian troops if memory serves correctly. The second man on the line has a flat top receiver and his 516 isn't pushed as far forward on the receiver as he can get it, in fact his is about mid receiver, similar to how many Russian optics are mounted on AKs (having had a 74M, there are lots of side mount rails that allow mounting of optics anywhere over the dust cover, but still most I see are mid or rear receiver). With the AK weight is more of an issue, so it makes absolute sense there, but this appears to be the case with the AR as well which was my primary reason for switching. It's lighter, but not that much lighter that I can get away with certain things and as mentioned there are other caveats like POI shift from the rail.

35740

"That is the trouble with many inventors; they lack patience. They lack the willingness to work a thing out slowly and clearly and sharply in their mind, so that they can actually "feel it work". They want to try their first idea right off; and the result is they use up lots of money and lots of good material, only to find eventually that they are working in the wrong direction. We all make mistakes, and it is better to make them before we begin." Nikola Tesla

[mkmckinley]

Don't take what one guy does as gospel. I've seen some "cool guys" with some pretty jacked up weapon configurations. Maybe he's just trying that mounting position out for shits and grins when that picture was taken.

Mounting toward the front of the receiver is the best compromise between weapon balance, fields of view both through the optic and around it, and use of rail estate for different add-ons. Also consider that precision shots can be aided by placing the red dot on top of the front sight post. Finally, some RDS mounts overhand the front of the receiver slightly. This can help keep the handguard in place on some handguard designs which keeps the IR laser zeroed.

[win&legend]

Don't take what one guy does as gospel. I've seen some "cool guys" with some pretty jacked up weapon configurations. Maybe he's just trying that mounting position out for shits and grins when that picture was taken.

Mounting toward the front of the receiver is the best compromise between weapon balance, fields of view both through the optic and around it, and use of rail estate for different add-ons. Also consider that precision shots can be aided by placing the red dot on top of the front sight post. Finally, some RDS mounts overhand the front of the receiver slightly. This can help keep the hand guard in place on some hand guard designs which keeps the IR laser zeroed.

Agreed, because one person does it does not mean it works, on the contrary, because everyone does does not mean it works either, or that there isn't a better way. That is not however a lone instance, I've done several searches with simple combinations of nouns like Army Special Forces or Marine Special Operations and the majority of photos taken where EOTechs are used have the optics placed about mid receiver. There are some who do place the optics all the way to the front of the receiver even if they don't have a magnifier on there, but if I had to guess, from my own training under Marine instructors, hence why I"m doing V-tac drills etc. is that fatigue for me is a big issue over time. I could imagine the effects stress have on the body when it's not just a clock your trying to beat.

I'll have to experiment and see what I actually shoot better with, I've used the forward receiver position before and it was good, which is why I decided to push the concept further by going onto the rail in the scout position (similar to what I did with AK's and the Ultimak rails, but those rails were locked into place to the trunion), but I've yet to try mid receiver positions. Here are some more examples, just a collection of photos showing a common theme (but also the outliers):

3574535746357473574835749

[win&legend]

3575035751

One of the photos has some XPS's on the forward most part of the receiver, but XPS's are 1/4 lb lighter in weight than the older 512 series which is what I have and seems to be the most common due to it's low cost and use of widely available AA's (I use Lithium AA's so run time is double a single CR123). Obviously using a magnifier would require a forward receiver position simply due to receiver space available and some of them are rear mounted due to PEQ's etc but others have room in front. It's interesting to see that even when they could mount them more forward. I'd bet my bottom dollar it's due to endurance reasons which is in my opinion the bigger advantage of bull pup designs than their compact size (IMI Tayvor, Styer AUG etc.).

[Inuvik]

This is the Precision Semi-Auto Rifle sub-forum. The Eotechs in all of your sample photos would not generally be considered a precision optic, and the way they are mounted is usually quite different from a variable-powered scope. Based on the description on your first post, I would have expended you to be looking at examples of Mk12 or Recce rifles instead of the carbines you are evidentially looking at as examples. The photo sticky at the top of this sub-forum may be a good reference for you as well.

[win&legend]

This is the Precision Semi-Auto Rifle sub-forum. The Eotechs in all of your sample photos would not generally be considered a precision optic, and the way they are mounted is usually quite different from a variable-powered scope. Based on the description on your first post, I would have expended you to be looking at examples of Mk12 or Recce rifles instead of the carbines you are evidentially looking at as examples. The photo sticky at the top of this sub-forum may be a good reference for you as well.

I guess we all interpret precision differently. I could consider a precision rifle to be reasonably effective beyond close quarters (0 to 100). So mid range, 100m to 500m, in my opinion is still considered precision as it's not easy to make real world shots at those distances. While unlikely, they are not impossible conditions a person could expect to encounter, especially if you live in open country or are very near open country (like me). But thanks for the pointer, I'll take a look.

[prdubi]

I have a heavy bias against Night Force because of their past warranty for several customers that had their product and they refused to fix it under warranty.

My personal favorite was that acts of God are not covered on the warranty. Then they had the audacity to charge for looking at it.
I hear they are different now....but I'll stick with optics that back their stuff no matter what.

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[T2C]

I have a heavy bias against Night Force because of their past warranty for several customers that had their product and they refused to fix it under warranty.

My personal favorite was that acts of God are not covered on the warranty. Then they had the audacity to charge for looking at it.
I hear they are different now....but I'll stick with optics that back their stuff no matter what.

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What happened to the optic that was damaged from an act of God?

[Failure2Stop]

I have a heavy bias against Night Force because of their past warranty for several customers that had their product and they refused to fix it under warranty.

My personal favorite was that acts of God are not covered on the warranty. Then they had the audacity to charge for looking at it.
I hear they are different now....but I'll stick with optics that back their stuff no matter what.

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I'm not following how this post is relevant to the discussion.

[Failure2Stop]

I had to re-read your original post, as there are a few ways that one could come into this topic, but I think that you are missing out on some fundamental aspects of rifle/carbine marksmanship.

The cheek/jaw should contact and remain on the stock from presentation to the completion of the shot string. The distance of movement is irrelevant, as the head moves with the gun as a single unit. Lack of this "cheek weld" and the resulting "chin weld" or "floating cheek" from using an optic that is mounted too high (such as common with piggybacked optics) is what causes most users to shy away from them, as precision presentation is severely lacking and tracking the dot during a shot string is more difficult.

When it comes to iron sights, you have two points that occupy the extremes of possible placement as outlined in your original post. The fact is that trained people do not have an issue with either sight showing excessive movement when being used.
Why? Cheek weld. The head is attached to the rifle as an integral part of the sighting system.
The head/eye is moved only to achieve correct eye relief and sight alignment.

Are there advantages to moving the optic fore or aft on the gun?
Yup.
And yes, accuracy is one of those.
When the optic is moved away from the eye, it is easier to center the dot in the "smaller" aperture of the optic. Since glass induces parallax at all but one distance, shooting with the dot out of center will cause shots to move away from the point of aim. It's not a whole lot, but it is a measurable affect.

Moving the optic toward the eye will give the shooter a greater "field of dot", as the aperture will appear larger. This becomes advantageous when using optics with smaller tubes/windows in unconventional positions where achieving perfect head position behind the optic is difficult or time consuming.

So, while moving the optic does play a part in accuracy, cheek weld is what ties everything together.

[win&legend]

I'm not following how this post is relevant to the discussion.

That makes two of us, not sure how that started on this thread lol.

[win&legend]

Right, but cheek weld isn't the issue here. We are talking about the same rifle, same optic and same user including same hand positions. The only change is the optic location. What I am really after is the optimal balance of correlation between arm movement and reticle movement in relation to fatigue from the shift in weight. If you go to the first page and look at the simple diagram i posted, we can see that moving the optic changes the amplification effect of reticle movement from the shooter's perspective. This translates in to a "feel" and affects brain / arm coordination, although I'd argue this can be trained over time, what doesn't feel natural, if practiced well can become natural.

While the same arm movement is necessary to get the rifle on target, the reticle will appear to be further away but move faster in the scout position (un-dampened response), while in the rear position it will appear close to the target but move slower (dampened response), again given in both scenarios all other things are equal. Now in the real world we also contend with the weight being shifted more to the support arm, which increases the rate of fatigue, which in turn decreases accuracy and precision. I was curious as to what others thought to be the most practical optic position for close quarters.

[pyrotechnic]

Reticle movent in relation to the target as percieved by the shooter will be the same. Although the optic will physically move more distance the further forward it is mounted. F2S's points on centering the dot in the optic and percieved field of view are really the only changes, and as he stated consistency in POI is dependant on consistency in cheak weld. When talking about magnified optics with set eye relief, the point is kind of moot as eye relief will dictate optic placement.

[Failure2Stop]

Right, but cheek weld isn't the issue here. We are talking about the same rifle, same optic and same user including same hand positions. The only change is the optic location. What I am really after is the optimal balance of correlation between arm movement and reticle movement in relation to fatigue from the shift in weight. If you go to the first page and look at the simple diagram i posted, we can see that moving the optic changes the amplification effect of reticle movement from the shooter's perspective. This translates in to a "feel" and affects brain / arm coordination, although I'd argue this can be trained over time, what doesn't feel natural, if practiced well can become natural.

While the same arm movement is necessary to get the rifle on target, the reticle will appear to be further away but move faster in the scout position (un-dampened response), while in the rear position it will appear close to the target but move slower (dampened response), again given in both scenarios all other things are equal. Now in the real world we also contend with the weight being shifted more to the support arm, which increases the rate of fatigue, which in turn decreases accuracy and precision. I was curious as to what others thought to be the most practical optic position for close quarters.

So, if the question is really a simple matter of leverage working against the shooter, I'd recommend a small, light optic such as the Aimpoint T1. Its weight is pretty negligible, regardless of placement. I recommend placing it somewhere on the upper receiver, or if using something with a truly continuous top rail, somewhere within a few slots of the magazine well back to the iron sight.

I have some time with an AK with an UltiMak rail with a T1 just forward of the rear sight and found it to be a little further out than I prefer. Not due to weight, but rather that the tube didn't "disappear" as much with both eyes focusing on target like it does when on the upper receiver of an AR. I like my T1s just forward of the rear sight. This position doesn't let me mount a magnifier behind it, but the smaller tube closer to my eye is worth it to me. Frankly, the weight isn't a factor. I grew up in the military carrying SAWs, M16s with M203s, MK 11s, and the like, all with lasers, lights, etc. bolted to them, that are all significantly more heavy than modern 5.56 carbines. In application, the gun isn't held in a standing position staring through the RDS all that long. Shooting solutions when standing tend to resolve pretty fast or a more stable/supported position is utilized. I recommend choosing an optic position that best permits a rapid presentation and the ability to be used when crunched into an uncomfortable position.

[sua175]

I always laugh at the guys who freak out over fraction of ounces for their pow. If you are worried that your personal weapon is too heavy then your training priorities are ****ed up. I guess it is easier for some to spend more money to make a light gun even lighter as opposed to hitting the gym and stop stuffing thy face!


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[win&legend]

Right but the T1 costs 2x as much. Holographic sights also allow for better precision shooting due to the finer reticle size and the fact that they are truly parallax free from their focal distance (100m in this case) to infinity, there is some parallax with a reflected reticle of a red dot, but the further the distance the less the effect. I previously had an Aimpoint Pro on an AK and I had several inches of shift in the POI from the POA at 100+ if the reticle wasn't centered in the tube vs. the holographic didn't have that issue at 100 and beyond, the reticle tracked in a 1:1 relation with the target as advertised.

Now perhaps that's an unrealistic comparison as I was shooting for the tightest three shot groups I could manage, prone supported, but it bothered me enough to switch. I figured it's hard enough to hit a real target under stress, why add to the probability of a miss. My father had the same issue with one of his T1's on a rifle barreled Mossberg 1100, because he didn't have a good cheek weld (like the AK it was more of a jaw or chin weld) he couldn't zero the darn thing because he couldn't consistently keep the dot centered in the tube so he stuck the T1 on his AR and put an XPS on the 1100 and is happy with both.

Now I have an AR so with a proper cheek weld that would be a non issue (forgive my ramble), but I kept the 512 when I switched so that's what I have. If the statement about short lived standing engagements is generally true, perhaps the weight isn't much of an issue as I would be forced into a supported position, so perhaps I'm just over thinking this whole thing...as I stated previously, I'll give the different positions a fair try through a couple of 8 hour rifle courses, so I guess ultimately I'll find what does and does not work. If my 512 ever goes belly up, I"ll give the cheaper H1 a good look as a replacement. Thanks for the input guys.

[win&legend]

One more thought, some one mentioned previously that the rail is probably not a stable enough platform for mounting optics. I can confirm that, I can flex the rail quite a bit and visually see it move several mm. Although it returns to it's position, I did try the optic out on the rail one class out of curiosity and during a v-tac drill I couldn't hit the gong at 50 for the life of me. It was embarrassing, until I realized I was pulling down on the rail with the barrel supported by the cutout, thus causing my optics POA to shift. Once I figure that out I was careful not to do it as much as possible, but there were positions where it was difficult not to have some pressure on the barrel and rail. This goes to show why optics or even iron sights should not be mounted on rails! I thought at first it was a loose barrel nut or my optic came loose, but it wasn't until I got home and checked those that the realization came to.

[win&legend]

I always laugh at the guys who freak out over fraction of ounces for their pow. If you are worried that your personal weapon is too heavy then your training priorities are ****ed up. I guess it is easier for some to spend more money to make a light gun even lighter as opposed to hitting the gym and stop stuffing thy face!


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Yes and no. Weight matters, buy only to a point. With all of the accessories people put on, it often seems to create a new problem which then requires another addition to solve. This is particularly true with traditional quad rails (which I'm stuck with because nobody makes a key mod rail yet for piston AR's, at least not in the 12" length that I'm aware of), as they are not comfortable to hold and add weight but allow the addition of useful components such as grips, lights, lasers etc. But all that adds weight so the lightweight AR is no longer light weight! No matter how strong you are though, you will fatigue and a lb can make a drastic difference when its over hours length of time or when your exhausted.

I can tell you from my carbine classes after doing timed qualification's and having to sprint that trying to shoot with a heavy rifle while breathing hard even at 25m is not that easy. The lighter the rifle the easier it is to use when your fatigued or winded. That was one of the whole design concepts behind the original M16 (other than the small caliber higher ammo capacity), it was much lighter in weight than it's bigger caliber brethren. But, yes, I think it's quite silly to spend hundreds of dollars to shave off only an ounce or two of weight. Maybe for 8 oz it would be worth it...

[sua175]

In a military sense, you are limited by the equipment you are required to run, if a already super light commercial ar15 with a modern light weight rail is already too heavy then yes you have a fitness problem. I have never take a civilian class, but if you are "fatiguing" from doing flat range drills even in body armor, then yes you have a fitness problem.

My perspective is a little differenct because where I come from, you are only as good as your slowest guy which in a fire team will always be the AR/saw dude. I just love all the people who spend all the money on gear and weapons training but spend little to zero time physically training, as far as a combat and defensive situation is concerned your fitness could be the most important factor to surviving. If you can shoot your gun like a OG standing still but can't run a mile with it and then effectively engage, you might be training wrong. There is nothing wrong with quad rails. I have carried a RIS II and Knights RIS up many a mountains and never felt my weapon was limiting me because it was too heavy, and I guarantee my work gun with LA5, optic, light was heavier than %90 of commercial ar15s that people have.


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[sua175]

Yes and no. Weight matters, buy only to a point. With all of the accessories people put on, it often seems to create a new problem which then requires another addition to solve. This is particularly true with traditional quad rails (which I'm stuck with because nobody makes a key mod rail yet for piston AR's, at least not in the 12" length that I'm aware of), as they are not comfortable to hold and add weight but allow the addition of useful components such as grips, lights, lasers etc. But all that adds weight so the lightweight AR is no longer light weight! No matter how strong you are though, you will fatigue and a lb can make a drastic difference when its over hours length of time or when your exhausted.

I can tell you from my carbine classes after doing timed qualification's and having to sprint that trying to shoot with a heavy rifle while breathing hard even at 25m is not that easy. The lighter the rifle the easier it is to use when your fatigued or winded. That was one of the whole design concepts behind the original M16 (other than the small caliber higher ammo capacity), it was much lighter in weight than it's bigger caliber brethren. But, yes, I think it's quite silly to spend hundreds of dollars to shave off only an ounce or two of weight. Maybe for 8 oz it would be worth it...

And I was not talking about the progression of technology, I was strictly talking about modern light weight carbines


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[sua175]

Delete

[win&legend]

In a military sense, you are limited by the equipment you are required to run, if a already super light commercial ar15 with a modern light weight rail is already too heavy then yes you have a fitness problem. I have never take a civilian class, but if you are "fatiguing" from doing flat range drills even in body armor, then yes you have a fitness problem.

My perspective is a little differenct because where I come from, you are only as good as your slowest guy which in a fire team will always be the AR/saw dude. I just love all the people who spend all the money on gear and weapons training but spend little to zero time physically training, as far as a combat and defensive situation is concerned your fitness could be the most important factor to surviving. If you can shoot your gun like a OG standing still but can't run a mile with it and then effectively engage, you might be training wrong. There is nothing wrong with quad rails. I have carried a RIS II and Knights RIS up many a mountains and never felt my weapon was limiting me because it was too heavy, and I guarantee my work gun with LA5, optic, light was heavier than %90 of commercial ar15s that people have.


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Your assuming that I take no time to physically train when that's quite the opposite. I spend at least an hour three to four days a week to keep in good shape. I also have 30% less lung capacity than a normal male due to scar tissue from pneumonia when I was a child, cardio intensive movements are difficult for me. And no, my rifle is not what one would call super light, it weighs 9.7 lb fully loaded, which is just a light, 12" quad rail with AFG2 and the optic, which is about what I see most people running including military and LEO's. Yes there are ultra light rifles that use T1's, super low weight skeletal rails and pencil barrels that are well over a pound or more lighter but I didn't have those options with a piston AR (nor the money) due to the larger gas block so I went with a Samson STAR-CXR quad rail that weighs 16 oz. Moving that 3/4 lb EOTech 512 onto the rail centered between the gas block and front of the receiver is what shifted the weight enough that I started to feel fatigued when pushing myself, I never had an issue with it mounted on the receiver.

The original purpose of my post was to get some thoughts on how much of an advantage or disadvantage it was to have it mounted in a more extreme scout position vs how long I would typically need to be able to shoot unsupported. Ultimately I've had to abandon mounting it on the rail as I encountered accuracy issues in certain situations where I need to put pressure on the rail (different supported positions such as in a V-Tac drill), causing it to flex and throw off my POA so I guess it's some what of a moot point now. And no there's nothing wrong is quad rails, I never said there was, I just find them to be very uncomfortable to grip without accessories like AFG's, VFG's or rail panels which adds even more weight. Weight does matter, because you didn't encounter a situation where it didn't doesn't mean you won't ever, but it also doesn't mean you will. Everything is just a hedge against the odds to some degree, some hedges are better than others though.

[trinydex]

Speed and endurance are the two advantages to a rearward mounting position. The disadvantage is precision as the same motion of the muzzle results in less detectable movement of the reticle by your eye, making precision shots at longer ranges more difficult.

i think the advantage of the forward mounting position that you describe is somewhat mitigated by the "floating" nature of red dot and holographic sights. if you have a fixed reticle then the motion of the reticle can easily be seen. the harder it is to keep the reticle still, the more inherent accuracy will be produced. this is similar to sight radius, the harder it is to keep the front sight in the middle of the ghost ring or the notch, the more error is reduced and the solid angle of deviation is minimized. this is not exactly the case for red dot or holographic sights.


the closer the red dot is the more the shooter is shooting through the tube, the further it is the more the shooter can see around the tube. the further the red dot is away the more the shooter has to stabilize the tube to see the dot, however, i'm not convinced this inherently reduces error and hence solid angle of deviation. the head can move and the dot would follow, it's all about putting the dot on the target. it's not any harder to place the dot on the target (project the dot) when the dot is close or when it's far.


feel free to disagree, but i'm not really convinced the same mechanisms are at work here.