Various optics for the AR-15 make for a very frequent topic on here, so I thought that a brief aside on a somewhat particular case might be in order.
Here, in the great state of New Mexico, Democrats have a super majority so by and large they do whatever the hell they want and keep on getting re-elected. Once in a blue moon, however, they do pay attention to the voters.
A little earlier this year, they proposed a set of anti-2A laws that would make Gavin Newsom cream into his g-string a little (for the politically correct out there: I have not idea what underwear the esteemed Mr Newsom prefers, but he sure looks like he's got something uncomfortable up his ass at all times), they got so much apparently explicit feedback that most of it did not make it out of the committee. Naturally, there were also a few lawsuits getting ready to go. It did, for a moment, look like AR-15s would get outlawed in out state.

Unbeknownst to me, a friend of mine decided that he should probably pick up an AR-15 while he still can. Had he told me about it, I would have built him one in any configuration he wants, but he did not tell me and I did not know he was looking to get one.

I learned about all of this well after he bought the rifle when he asked which red dot and magnifier he should get.

The primary purpose of the gun is self-defense, general purpose plinking and occasional shooting beyond MPBR. The gentleman who owns the rifle has reasonable experience with shooting. I saw him shoot and his fundamentals are perfectly reasonable. However, he has been out of it for a while and he is planning to pick this hobby back up.

I did some digging around the safe and found what I think is a reasonable solution for his needs, but the project is not yet entirely done.

There is a good chance that he will read this, so what follows in the next few sentences has a real chance of hurting his feelings a bit. I think I can live with that. I am pretty certain he can too.

The specific configuration of an AR-15 that he bought makes no sense. I do not know why S&W makes it that way. I do not know why a self-respecting gunshop would carry it. Maybe the margins are good, but given how evolved modern ARs are and how easy it is to find a better configuration, this is odd to me.

Before I crap all over it any further: it seems adequately accurate. It did not display any reliability issues during the one shooting session we had with the gun. It is a perfectly competent AR, except the configuration makes no sense.

The carbine appears to be a version of S&W's M&P Sport II product line, kinda like the MOE version here: https://www.smith-wesson.com/product/m-p-15-sport-ii-with-magpul-moe-m-lok-
except his came with a Magpul buttstock. Interestingly, the castle nut was loose and a quick look suggested that there is not threadlocking compound on it. Not sure if it came like that from S&W or if the gunshop people were messing with something.

Let's go over the highlights:

16" barrel with threaded muzzle and A2 flashhider -- perfectly reasonable

Melonite finish -- this is a good thing.

5.56 chamber -- I'd prefer an intermediate chamber, but this is not a major deal

1-in-9" barrel twist -- this one is just retarded. Why do people still do this? Most 5.56/223 loads with decent terminal ballistics will not reliably stabilize in this barrel. It will work fine with 55gr plinking ammo. It starts getting marginal with bullets heavier than 60-62 grains. It will work with some 69gr ammo that uses shorter bullets. If you want good terminal ballistics, your best bet is probably Barnes 55gr load ( https://bit.ly/3zZZFVu). 62gr TSX may or may not stabilize. Unless you are building a dedicated varminter, go with either 1-8" or 1-7" twist.

Carbine gas system -- why would you put carbine gas system onto a 16" barrel? Mid-length gas system on a 16" barrel seems pretty standard and gets you a mellower recoil cycle.

Medium weight barrel -- I am not sure what it is under the handguard, but forward of the gas block, it appears to be right around 0.7" diameter. On a fairly basic carbine not intended for distance, all it does is make the gun heavier and the handling poorer. If there ever was a good application for a pencil barrel, this is it.

Fixed tower A2 front sight -- I am not a fan, but that's a personal preference. If you plan to use optics, a fold down BUIS is a better option in my mind.

Non-free floating MOE handguard -- if there is a good reason for it other than profit margins, I'll be damned if I know what it is. There is a TON of simple free floating handguards out there with almost all of them being a better option than this. Eventually, I'll replace this monstrosity with a two piece handguard from MI (https://bit.ly/3UGqyHn) or something along those lines. I've had good luck with MI handguards, so that will likely be the way to go if he chooses to keep the fixed front sight. The gas block looks to be nicely pinned, so it might be a b@#$% to remove. I have seen some that could only be removed with a prayer and a jackhammer.

Magpul folding rear sight -- this is a perfectly reasonable budget option.

A2 grip -- other than it not being designed for human hands, there is really nothing wrong with it.

In the grand scheme of things, all of this is fixable and me bitching about is mostly a reflection of my personal preferences. It is a perfectly reasonable first AR for someone getting back to shooting. Over time, he will figure out what works for him and what does not.

So far, I set him up with optics (which we will cover next). In the next few days, I will take it apart to take a closer look at everything. After that, I will cinch everything down with loctite where appropriate and swap out the grip for something better.

The gentleman who owns the rifle has had some experience with red dot sights and, since he already has irons on there, that seemed like a good way to go. However, given that I was pretty certain he will want to stretch the distance at some point, I though that he could use a little magnification. Well, I have plenty of red dots and magnifiers here. Personally, I really like ultra compact magnifiers, but if you want to retain a folding BUIS rear, you will have eye relief issues with pretty much all of them. I do have a few full size magnifiers around. They are still pretty small, but bigger than the compacts. That means the eyepiece extends further back and we have a better chance of getting one of these to work.

In the specific case of this carbine, we set it up with Primary Arms MD-25 red dot sight https://bit.ly/3IBbPcq and PA's SLx FS 3x magnifier https://bit.ly/3UBkNuR

I do not know what exact sighting system he will settle on eventually, so it did not make sense to invest into a higher end optic. Besides, MD-25 has been nicely robust in my experience (frankly, for around $140 at the moment, it is a steal). Slightly larger optic diameter does work better with magnifiers which is important in this situation. ACSS CQB reticle, combined with a magnifier, will let him shoot at plates out to 500/600 yards depending on how we do the final sight in. The 3x SLx magnifier is quite respectable optically, so it is very doable.

If you look at the picture carefully, the magnifier is still not quite as far back as it needs to be for comfort. I think I can push it back a little further and, next time we meet, I will have him go through a range of shooting positions to finetune this a little bit.

Most magnifiers do not have all the flexible of eye relief which can cause problems as you transition between shooting positions. Collapsible stock can help with that, of course. It is not uncommon to set the stock up a click or two longer for shooting prone than standing.

We'll see how it pans out. Ultimately, the magnifier needs to be just right when shooting prone. Shooting quickly off hand would normally imply that the magnifier is flipped to the side.

If we can't get this one properly set up, I think I have a few more magnifiers here somewhere that are a little bit longer.