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Page AR-15 » Optics, Mounts, and Sights
AR Sponsor: bravocompany
Posted: 5/9/2003 5:50:54 PM EDT
Would some of you gent,s please be so kind as to explain the bac concept to those of us that don,t know our ass,s from a hole in the ground.(at least as far as acog,s go).thanx gent,s,
Link Posted: 5/9/2003 6:01:53 PM EDT

This ought to help. Basically it is a reticle with 2 unpowered light sources.
Link Posted: 5/9/2003 7:33:43 PM EDT
Thanx thinman.I thought it was something to do with being able to use both eye,s open.I appreciate that.
Link Posted: 5/10/2003 12:28:58 AM EDT
Did you read the tacked thread at the top?  This was my answer to that but I copied it for you in case you are too lazy to find it... [;)]

The Trijicon BAC system allows you to use the illuminated reticle from the right eye and your unmagnified view from the left eye. As you sweep to a close target the blur of motion in your right eye makes it like looking through an occluded gunsite... you dont notice it. In fact you could put a cover on the objective lens and still use the BAC system for close range. Only when you stop and the piture becomes stable will your brain automatically zoom in by using the sight picture from the right eye. With practice you can actually ignore the zoomed view and only use it when you want to. At first though its easy to use when you are swinging the scope on target but you almost cant stop yourself from seeing the magnified view once you quit moving.
Link Posted: 5/10/2003 6:01:41 AM EDT
That wae the explanation i remember reading.I thought it was new -arguy that had postef,maybe that,s why i could,nt find it last night.But when your right,your right.I guess.thanx devl
Link Posted: 5/10/2003 2:50:09 PM EDT
I always thought Trijicon advertised these as if they worked with the weapon stationay-  So I always said No- it doesn't work as advertised.

But if it was only inteded for use while sweeping the weapon- that makes perfect sence and does work. although I don't know how accurate a shot while sweeping would be.

The Armson sights work stationary or sweeping but they are not magnified and operate as scope cover closed with ACOG (of course a aimpoint is better by far than a Armson)

[b]Thanks for the post that clarifies a lot.[/b]
Link Posted: 5/10/2003 5:25:55 PM EDT
Its really designed to help getting a distnat target into the scopes field of view NOW instead of hunting for it or something supprising you at close range.  If you have time enough to quit swinging the weapon to target and aim you should just use the magnified view anyway.  However the BAC is a bit less than ideal for CQB work as I normally have to tilt the rifle down slightly and try to not use the scopes magnified view till I see something to shoot where with a dot scope you keep the rifle up and always have something sighted in (like the edge of the wall at a T intersection of hallway)  Also remember that when you are under life or death stress your pupils dialate and you lose the ability to focus near and will lock onto the threat.  At that point you will only be using the BAC portion of the scope.  At longer distances where you can relax the magnification will click in automatically.  I dont know if others use the slight tilt down method and look up slightly with the eyes for room clearing but it works for me.  If I dont do it I keep having the magnified view pop into my view every once in a while and its distracting.

This inability to hold the rifle on target while moving in tight confines is why I hope that Trijicon hurries up with a 1-3X or 1-4X power variable scope.  I used to think BAC could do it all but it slows me down because of the amount of time to bring the wepon up a few inches and the POI is slightly off in BAC mode.  A 1X setting would solve both problems.  The high power setting would still work like a traditional BAC scope.
Link Posted: 5/12/2003 7:35:47 PM EDT

What you are talking about (with the BAC in room clearing and scaning for targets) is exactly the reason I have decided to stay with my Docter/NSN set up instead of a BAC scope.  Instead of a 1X-3X variable power scope I think Trijicon should make a dual optic scope with the red dot housing being part of the occular casting.  This would help with the durability of the red dot.  Just a thought.
Link Posted: 5/12/2003 8:53:07 PM EDT
Dev, I dunno man. I've been using BAC ACOGs now for close to three years I'd say. I've used them in a lot of different environments. Light, dark, inside, outside, sunny, raining, daytime, night time, very close quarters, all the way out to 450 yards. The only time I had trouble with the BAC was when I first got it. I dont know what you mean by having to lower the rifle. I've never once had to do something like that. So long as I keep both eyes open, the unmagnified view stays in focus.

As you know, the way BAC works when you are moving around in fast paced, fluid shooting is because the magnified view is too blurry and out of focus for your brain. Therefore it ignores that image and concentrates on the unmagnified view. Think about it, in close quarters, the magnification of ACOGs makes targets and objects that are very close quite blurry. This is because they are too close to really focus on. I believe this is why I have never had a problem with BAC in close quarters. The magnified image of the walls and objects that are so close to you are never in a tight focus through the ACOG. They are too close. Therefore, for me, the unmagnified view remains constant for me.

I just ran around my place 3 times clearing rooms to confirm this. I tried moving quickly, I tried moving slowly. I tried it in lit rooms, I tried it in dark rooms. I tried it from lit room to dark rooms and the other way around. I tried it in dark rooms with no light, I tried it in dark rooms with the Surefire. I tried it with the Sirefire and blue filter, I tried it without the filter. And like I said, I never once had a problem with the magnified image distracting me.

Interestingly enough, just for kicks, on my last run of the place, when coming out of the bedroom and into the living room, I was facing my glass patio door. At that point, I searched from inside through the window to the outsie. From there I can see whats got to be a clear 300 yards out to the main street. When I came out, looked out the window, the magnified view took over. Im telling you, I love this thing.

One thing I do know is that when using the BAC, I never look "into" the scope. I never look at the reticle. I am always looking at the target area. So long as I do this, the little red donut just floats around in the unmagnified view. If I were to try and focus on the donut, things would get blurry and confusing. Thats the trouble I had when I first got it. I was trying to look into the scope, at the reticle. Once I stopped that and focused on the target area, everything started to fall into place.

The only thing I have to be aware of is my head position behind the optic. Because of the shorter eye relief on the TA31 I am using, you have to more or less keep your head locked in behind the glass. Not 100% locked in, you do have "some" room to play with, but head position on the TA31 is more critical than say a TA11 or 1.5X or 2X Compact ACOG. And *A LOT* more critical than with something like my Aimpoint.

Again, nothing is perfect, but sheesh, the TA31 sure as heck comes close. I'll deal with the tighter head position to gain all the other advantages this thing offers! As always, YMMV.
Link Posted: 5/12/2003 9:31:00 PM EDT
I dont have trouble in very tight confines but in longer indoor scenarios like very long hallways, warehouses and the like where I am moving in a slow straight line.  I maintain my cheekweld and just aim down 15 degrees or so and look up with my eyes if I dont want to see the magnified view.  Its a very slight tilt and I only use it in close but not too close scenarios where the rifle is not moving a lot.

I think the bigger issue is POA/POI for very close in shots.  You can hit center mass every time but I wonder what would happen if you tried across the room head shots while moving.  I have not had the opportunity to take a carbine class yet.  Have you tried this and what was your accuracy like Neil?
Link Posted: 5/12/2003 11:05:51 PM EDT
Sure, I've taken about 2 different classes with the TA31, and dozens of FDCC courses. Head shots and/or multiple targets while moving is not the easiest job with any sighting system, and takes a fair amount of skill. However, the only problems I have ever encountered was making quick hits within the rather small hit zone on the head of an IPSC target durring the Morrigan Consulting 3 day advanced carbine class last November. This however, was not due to the difference in POA/POI phoria may create. I realize phoria is better or worse for some than others. For me it is rather slight. And its never been so much as to cause me to miss a shot.
Link Posted: 5/13/2003 7:54:24 PM EDT
At ranges from the barrel out to about 25 feet I have no problem hitting the center of mass using the pistol grip and barrel. Just point and shoot, repeat if needed.

Beyond that out to about 100 feet (which is a really really big CQB house) the iron sights work well enough. Honestly I have actually used my iron sights out to 100 yards and beyond! No really. [:)]

Beyond 100 yards the added magnification of the scope helps. The ACOG is not meant to be used for CQB. Try a red dot in this application with their larger and brighter dots/triangles/doughnuts.
Link Posted: 5/13/2003 10:11:30 PM EDT
I disagree. BAC ACOGs are meant to be used in both CQB and longer ranges. In my opinion, its what the design is all about.
Link Posted: 5/14/2003 3:03:40 PM EDT
Also remember that when you are under life or death stress your pupils dilate and you lose the ability to focus near and will lock onto the threat.
View Quote

Considering what DevL said, I think when you are in a house or other QCB area your [I] natural instinct [/I] will be to point and shoot at the threat, no matter what type of scope you have.
Before I got into red dots and scopes I always practiced the point and shoot technique with my pistol and rife for distances 8 to 10 yards.  I would set up a target and take single snap shots at it from the ready position, then progressed to double taps and finally to triple taps.  I got pretty good. The method even works well with stick bow archery (which is where I got the idea)! Thinking about it now while trying to decide on which ACOG to buy I am torn between the TA11 and the TA01NSN/Dr Optic setup.  The only thing I don’t like about the TA01 is the short eye relief.  
The other consideration that’s leaning me towards the TA01NSN/Dr Optic setup is the fact that I will only be doing perimeter patrol or bunkered in defensive type shooting if/when the SHTF; everything else in the mean time will be dealt with a pistol or shotgun, because I don’t want to loose my expensive tactical rifle over some nappy ass burglar or thug!  Anyhoo, I have read several places that the TA01NSN is [I]the [/I] recommended optic for perimeter patrol situations.  
The crosshair is very ungainly to work with in close quarter battle because it takes too much time to pick up.  For automatic fire, it is quite distracting to see the crosshair jump about and it is very easily lost while doing this.  That is one real issue with the NSN.  It would make a really nice perimeter weapon for LE, though.
View Quote
[url=www.snipercountry.com/InReviews/Optics_Test.htm] Review on TA01NSN here[/url]
The ONLY reason I may still go with the TA11 is because of longer eye relief.  I will have to attend the fun show this weekend and annoy venders by asking to look through all their ACOG's. [:D]

BTW, Is the Dr Optic always on, or does it have an on/off switch.  Someone said the thing will go w/o a battery replacement for up to 3 years!  
Link Posted: 5/14/2003 7:15:36 PM EDT
The Docter is always on.  It has a sensor that adjusts automaticaly to the lighting conditions.  the dot dims in the dark, so if you cover the sensor with the hood that comes with the sight it wil use less battery power.  Docter is claiming a six year battery life with their 3rd generation model with the hood in place.
Link Posted: 5/15/2003 2:42:58 AM EDT

What ammo are you going to use?  If you will be using 75 or 77 grain ammo remember the TA11 comes in .308 reticle which tracks amazingly well with the 75 or 77 grain rounds.  Its also cheaper and more rugged than the TA01+Dr Optic setup.
Link Posted: 5/15/2003 6:36:26 PM EDT
DevL, I'll only be shooting the 55gr and 62gr ammo.
Link Posted: 5/15/2003 9:50:37 PM EDT
The proof is in the puddin' boys and girls. This is taken from a Marine Coprs report on how our boys liked the TA31's they just got... My emphasis is added at the end.

[i]M16A4 with associated combat optic (ACOG 4x), the West Coast’s SAM Rifle ~ All interviewed were extremely pleased with the performance and felt it “answered the mail” for the role of the Squad Advanced Marksman (SAM). [u][/b]All said the fixed 4-power ACOG sight that was included was the perfect solution. It gave them the ability to identify targets at distance, under poor conditions, and maintained ability to quickly acquire the target in the close in (MOUT/room clearing) environment.[/u][/b][/i]

The whole report is posted on this thread;

Page AR-15 » Optics, Mounts, and Sights
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