ACOG/ELCAN Questions

[Nightcrawler]

Wow,it's been awhile. Still in MS. Not much longer though.

Anyhoo, with a bit of disposable income at my...um...disposal, I've finally ordered all of the pieces I need for my totally awesome FAL carbine.


Despite humming and hawing, I broke down and ordered a 16.25" Badger barrel from DSA. Now, they're extremely backordered, but as the phone-lady was checking on the price of another part for me, the production section guy told her they were just finishing up a barrel and it wasn't yet slated for an order. So I got it. Kinda cool knowing that my part was still being made as I was ordering it. (Odd contrast, considering my current barrel is 1960s vintage.)

Now, of course, I still desire a full length rifle, but I've consoled myself by telling myself that I can always get such a rifle later.

Anyhow, I'll have the rifle. Now I need the optic. Upon the advice of some of you guys, I've given both the ACOG and the ELCAN a good hard look. I like the ACOG a little better, I think, but I have some questions about both.

First off, the dumb one, so I'm going to get it over with. What's the "BAC" on the ACOG? DSA refers to this on their ACOG sales page, but they don't actually state what it is. I'm *assuming* that it's some kind of ballistic computing cam, wherein you turn a knob or something and the reticule is adjusted for range (meaning the crosshairs will hit spot-on at 400 meters instead of 200, for example). Is this correct?

If it is, or even if it isn't, but if the ACOG does have some kind of ballistic computing cam, I have a question. What about velocity?

See, these ballistic computer cams (sometimes referred to as a camputer, which I rate right up there with calling a fudge icecicle a fudgicle) adjust the crosshairs for different ranges, basically, doing your hold-over for you, correct? Question then. If you have a short barrel and thusly lower velocities, wouldn't the whole thing be thrown out of whack? I mean, the 300 feet per second difference between the M4 carbine and the M16 rifle doesn't effect end-result all that much, maybe, but it seems that it'd be enough to throw off a ballistic cam like that.

I belive both the ACOG and the ELCAN have ballistic compensation like this. Even though they're calibrated for .308, won't the shorter barrel (and 150-180 feet per second less velocity) throw off the point-of-impact? Or am I simply not understanding how the whole thing works? (Entirely possible.)

Anyway, moving on. Does the ACOG have some kind of channel in the mount for allowing access to iron sights? I seem to remember reading something along those lines. If so, that's fine, but if not, that's okay too. I plan on getting a quick-release mount for the scope in any case.

So, then, what's the best quick-release mount for the ACOG? Is one available for the ELCAN? Holding zero despite removal is, obviously, the most important point. Also, the mount needs to be tall enough to clear the rear sight (a paratrooper-style with the protective wings). Will I need spacers for this?

What's the machine gun reticle on the ELCAN look like? I've never seen a picture of it. I've heard it has some kind of range-finder in it?

Finally, where's the best place to buy either one? So far, the best prices I've seen are about $800 for the 4x32 7.62mm ACOG and about $1,000 for the ELCAN. Surely one can do better than that? Yes, I know that quality optics are worth the cost. However, if a deal can be found, then let's find it...

Thanks for the tips.

 

[Bartholomew Roberts]

First off, the dumb one, so I'm going to get it over with. What's the "BAC" on the ACOG? DSA refers to this on their ACOG sales page, but they don't actually state what it is. I'm *assuming* that it's some kind of ballistic computing cam, wherein you turn a knob or something and the reticule is adjusted for range (meaning the crosshairs will hit spot-on at 400 meters instead of 200, for example). Is this correct?

No. BAC refers to the Bindon Aiming Concept. Trijicon named it that after one of their founders, Glyn Bindon. This refers to using the scope with both eyes open, when you swing the scope your brain uses the unmagnified view from your weak eye; but you still see the reticle from your dominant eye superimposed over the view (it is similar to the Armson Occluded Eye Gunsight). Trijicon uses fiber-optics to supplement the tritium so that the reticle is lighted day or night and BAC is easier to use. ACOGs with the fiber optic/tritium lit reticle are referred to as BAC ACOGs in Trijicon literature.

The truth is, you can use the feature with almost any reticle that is bold enough that it contrasts well with the target. Also, BAC depends a lot on your eyes... however you can use it to place hits fairly quickly at close range; but they will be off from the point of aim.

If it is, or even if it isn't, but if the ACOG does have some kind of ballistic computing cam, I have a question. What about velocity?

The ACOG has an etched rangefinding reticle. To give an example of how this works on a BAC ACOG, let's look at the TA11F with chevron reticle. On a flattop AR15 with the appropriate barrel length firing 62gr ammo, if you zero the tip of the chevron at 100m, then the inside of the chevron will be on at 200m, and the post below the chevron will be on at 300m. Beyond that, there are 1 MOA crosshairs. Each one is the wdith of an E-silhouette (19") at the corresponding distance in meters (400m, 500m, 600m, 700m, 800m). So you just place the crosshair that best matches the width of the silhouette on the target and pull the trigger and you have the appropriate bullet drop.

As you have already figured out, if you change any aspect - the height over bore the reticle was designed for, the velocity of the round, the type of bullet, you also change how well the reticle tracks with that ammo. You can compensate for this to some degree by zeroing slightly higher or lower at 100m; but for the most part it is going to be off to some degree unless you perfectly match those aspects. Under 300m, it will be a pretty small difference; but at longer ranges it will be more noticeable.

I belive both the ACOG and the ELCAN have ballistic compensation like this. Even though they're calibrated for .308, won't the shorter barrel (and 150-180 feet per second less velocity) throw off the point-of-impact? Or am I simply not understanding how the whole thing works? (Entirely possible.)

Anyway, moving on. Does the ACOG have some kind of channel in the mount for allowing access to iron sights?

Yes; but that channel is designed for when the ACOG is mounted in the carry handle of an AR15. I wouldn't count on being able to use the FAL sights through that channel.

I plan on getting a quick-release mount for the scope in any case. So, then, what's the best quick-release mount for the ACOG?

I have both the Larue and ARMS #19S mounts for the ACOG. Both are high-quality mounts; but the Larue is nicer. Either should work fine on an FAL.... the ARMS is a hair taller.

What's the machine gun reticle on the ELCAN look like?

Here are the two Elcan reticles:
http://www.nightvisionweb.com/el_m_145.htm

I've never seen a picture of it. I've heard it has some kind of range-finder in it?

It has rangefinding etched into the reticle like the ACOG.

Finally, where's the best place to buy either one? So far, the best prices I've seen are about $800 for the 4x32 7.62mm ACOG and about $1,000 for the ELCAN. Surely one can do better than that? Yes, I know that quality optics are worth the cost. However, if a deal can be found, then let's find it...

Check the Equipment Exchange at AR15.com... sometimes you will see deals there. Both scopes are used by the military and are difficult to find at times.

 

[444]

I wouldn't get too hung up on the reticle thing. Yes, changing any part of the equation is going to change the results, but will the change be enough to matter ?
The first thing to do would be to zero the scope and then actually shoot at the ranges of the various crosshairs and see just how much difference there is. If there is a significant difference, then you can use a different crosshair at that range. This also works up close. In a recent class I used a TA31F ACOG on an AR: we did headshots at 15 and 25 yards. I was clued in by a Marine officer to use the 600 meter crosshair at 15 yards and the 400 meter crosshair at 25. In other words, the crosshairs become reference points even if they prove to be somewhat off from what they are marked.
During this class we got to put the rangefinding reticle of the ACOG to use. They had steel silhouettes scattered down through a valley and we were at the top. The instructors said they would spot for anyone that wanted them to, but the guys with ACOGs could range the targets themselves. I had never done it before, but it worked great. I was using a 14.5" barrel and 55 grain bullets. I don't even know what barrel length/load the TA31F was originally designed for.

 

[Zak Smith]

On smallish targets, just changing altitude 5000' can screw it up. So don't worry about the BDC being off. Shoot some K.D. targets to figure out the dope for your load in your rifle. I have used the TA11 ACOG to make first-round hits at 500 yards on silhouettes, and 400 yards on 10" plates (heavy 223 from a 17" - ie, NOT what the BDC was calibrated for).

 

[SnakeEater]

Go here for a cool demo of BAC http://www.trijicon.com/pdfs/BINDEN.swf

 

[444]

Here is another must read ACOG thread, posted by someone you might have heard of somewhere before: http://www.ar15.com/forums/topic.html?b=3&f=18&t=229420
The stuff about the .308 is on the third post of the thread.

 

[Nightcrawler]

Ahhh...I see now. Thanks, everyone. You're right, it must not matter much. The military seems quite happy to use ACOGs on 20" M16s and 14.5" M4s, and ELCANs on SAWs with 16" and 10" barrels.

Honestly, I think perhaps this kind of bullet drop calculator, just like the graduated sights on old bolt rifles, is probably less useful and originally thought. Say, you've got a standard SAW with the ELCAN on it (or even the rear battle sight, assuming you're in one of the rare units that actually found a front sight tool and zeroed the thing properly). Unless you're in stationary fighting position with an accurate range card (or happen to have a good rangefinder on you), the compensator cam probably isn't going to be all that useful.

That's the primary reason I decided to replace my FAL's rear sight with a para type. It doesn't adjust for elevation, but zeroed for 200, a bit of hold over should do it all the way past 400, and after that...well, that's what I'm buying a scope for.

 

[444]

Actually, the graduations on the reticle as well as the sights on old bolt rifles are quite useful.
One thing that is hard to face is that for many applications of firearms: pinpoint precision accuracy is unnessessary. Let's say that your rifle/load shoots three inches high of the 200 meter scope crosshair graduation. You see an enemy soldier at what you estimate to be 200 meters based on the width of his shoulders to the width of the scope crosshair labeled 200 meters (keep in mind that this range estimate is just that: an estimate: nothing here is precision/concrete). We hold COM (again, an estimate of COM) and fire. We pull off an absolutely perfect shot: when the trigger broke your reticle was exactly where you wanted it to be. However, because of your rifle/load the bullet strikes the enemy three inches high.
So what ?
That is plenty close enough.
Same goes for big game hunting, shooting at many reactive targets, personal defense etc. They arn't benchrest matches.
The reticle will give you a good guess as to the range, which will give you something to work with that will probably result in a good solid hit.
Moral of the story: we are not talking about being off by two feet or anything. It will be off by inches, which is good enough for it's intended purpose and I may dare say that is the intended use of your short FAL.
It will be a great combination that I feel certain that you will be happy with.

If we were in a fixed position with an ACCURATE range card, we could simply dial in the exact number of clicks nessessary for a dead on hold at that range. But, the ACOG isn't that kind of scope.

 

[Zak Smith]

Ahhh...I see now. Thanks, everyone. You're right, it must not matter much. The military seems quite happy to use ACOGs on 20" M16s and 14.5" M4s, and ELCANs on SAWs with 16" and 10" barrels.

Honestly, I think perhaps this kind of bullet drop calculator, just like the graduated sights on old bolt rifles, is probably less useful and originally thought.

They call it the "donut of death" because if you can see the target through the 2MOA inside of the donut, you will hit it out to about 300 yards....