I'm curious, is there a particular reason why reflective telescopes aren't really used for precision rifle optics?

Yes.

I have a somehow related idea. Instead of putting it on sideways, you could put a periscopic sight this way on a rifle. This could significantly lessen the distance between the barrel and the scope without making it any less comfortable. And it's also true for the red dot.

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This is now a navigation thread.

Would you be able to navigate using only a watch, the sun and the stars?

I could see that useful for long ops. Eye fatigue is a bitch and can play with your perception.

Anyone here have experience with spotting scopes? I want to get one that can see a 22lr shot at 200 yards, but have no idea on what to buy. The range I go to doesn't have steel targets, so I have to use paper.

In that case why not mount a very hi-def camera as the sights on your rifle and link it to a video eyepiece/glasses?

You just redesigned the Leopold DEVO.
It may have issues with thumb over bore shooters but for say an AK on a side rail mount that design would be awesome.

Northern hemisphere yes, no skills in that regard on the other side of the equator.

honestly, id just get a decent set of 10x60 binoculars that can be mounted on a tripod. probably more versatile than a spotter scope, and id think it would be more than adequate for sub 300 meter shooting. especially if youre just using it at the range, and dont really need the angled eyepiece. though if you have the money to burn, the larger aperture a good spotting scope provides is nice.

FÉLIN did that to an extent. I don't know how it performed or if it was even used, though.

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So at that point he'll be shooting 1.5 MOA at 25 yards and 7 MOA at 26 yards, right?

It's been done sporadically since WW1. Even in realm of trench warfare it only had marginal usefulness, you can imagine in modern warfare using stuff like that is a complete waste of time and money. It may be useful in police force, on account of there not being any pressure to accomplish the task as quickly as possible at expense of personnel safety, but to a soldier that thing is nothing but hindrance.

Could that have been a problem caused by lack of training? The periscope rifles they built in the trenches on the Western Front of WW1 were DIY hack jobs, everything else has been some kind of hyper-specialised prototype that soldiers have tried to use after X years training with conventional sights. A soldier who has trained since day 1 in doctrine and tactics designed around using that system would preform far better, and if nothing else would be able to return fire accurately with practically none of his body exposed to fire.

I have often wondered this myself. The larger amount of light coming in would allow for a larger, brighter, clearer picture. Better fine detail at very long range. The size is probably the only issue, Newtonian telescopes are typically larger diameter than conventional rifle scopes, but it would make an excellent spotting scope.

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Human limits of accuracy.

Does it outweigh the ability to keep both eyes open, giving you magnified sight and a superior FOV?

This bothers me too. Mirror optic has no chromatic aberrations and by design has inherent advantage in sharpens and resolution.

Despite common misconception optics cant amplify light. Even more: curious physics fact: passive light amplification device would be perpetual motion machine of second kind.

Light amplification device - device that increase contrast of image aka making bright parts more brighter comparing to dark parts.

As far as im aware, the "light amplification" is simply the result of a larger aperture concentrating onto the same area. Less amplification, more concentration of available light. But really, i dont notice any difference in brightness from 5x20 kiddy binocs and zwisse optics 10x80s that couldnt be put down to lense clarity. Not that ive really paid much attention, mind you.

You mean aside from price, weight, fragility and the fact that vehicle mounted "fire control units" are basically telescopes? Most aren't even portable and those that are take a long time to set up properly.

I want to make a giant magnifying glass and burn you off the face of the earth.

But that would just prove him right, because the glass isn't amplifying light, but concentrating a wide dispersal of energy onto a single point.

And you aren't an idiot, your cognitive capacity is just about two thirds below the mean.

Here is the thing. You can't transfer heat fro teh cold object to teh hot. Right? Wait but all objects with temperature above 0 kelvins radiate heat. What if we build huge ass magnifying glass and concentrate heat radiation thousands and thousands times from cold object to the hot? And by doing in that we make perpetual motion machine of second kind and solve energy problem forever. What is wrong with such idea?

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There is no "light amplification". Optics allow to see in dark better because their magnify objects. Larger objects (that appear to be closer) are better visible in the same lighting condition ( light levels and contrast ). Then why to have large objective for night? Well exit pupil diameter = objective diameter/ magnification.

30mm scope x8 magnification. 30/8=3.75mm. Pupil of military age male (18-27 yo) can dilate up to the 7-8mm in the night. So as you can see optic in our case BLOCKS potential light that can enter into eye. for x8 magnification objective lens should be as big as 65-70mm (8*8=64mm plus error margin of eye off center position) to illuminate entire area of the pupil. Past 70mm there would no increase of night time vision (for x8 magnification).

But here is the thing: no magnification (passive) optical system can not provide any increase of night vision no matter how big its objective is. Because it can't increase light intensity and contrasts.

P.S. Old people pupils dilate max to 4-5 mm so they can be satisfied with smaller objective lens scopes/binoculars during night comparing to the real soldiers (and obviously old people have about 2-3 times less nigh vision capability)

20%

because fuck my life

Assuming that you could 'solve' power requirements, could you mount a radio telescope as a sight on a rifle (however specialized)?

Nigger, just look at that fucking thing. It makes the gun entirely useless beyond periscope-mode plinking. Are you gonna carry two guns, one for trench shooting and the other for normal shooting? Are you gonna mount and unmount that huge piece of shit every time you need to switch mode of operation? Are you gonna entirely abstain from exposing yourself to the enemy, thereby compromising on priorities and putting everyone in danger? There's a reason why something as simple and obviously "effective" as a periscope have been made since WW1 but haven't seen wide adoption ever.

50%. The odds of any individual toss is always 2^-1 i.e. 50%. The odds of any specific sequence of tosses is 2^-n. So there's 1/1024 chance to toss heads 10 times in a row, or toss alternating sides 10 times in a row, whatever specific sequence you have in mind. But every individual toss is 50%.

I know you're fucking trolling but I'll bite. You can indeed transfer heat from cold objects to the hot but that requires power input. Otherwise, both objects will radiate at each other until their temperatures match. Heat flows from where it is hotter to where it is colder so your "energy concentrator" setup is actually an energy dissipator, it distributes energy from your central hot object to surrounding cold objects.

As you should know, radio telescopes have exactly 1 output pixel to work with. So it might not be as useful as you'd imagine.

A Finn developed something that could maybe work. But it still seems to be very impractical, especially because you'd need a gunshield for it to work propelly. And if your rifle has a shield on it anyway, then you are better off leaning out and aiming normally.

My point exactly. The only way it could be practical is if it had a micro camera on the siderail that sent picture to the helmet display. But that will only give you any advantage for so long, because the enemy will learn to abuse explosives and anti-material weapons to get you behind cover, and then you'll be in deeper shit than you could ever imagine.

You're forgetting about the possibility of it landing on edge.