[ny32182]

I used the proper TA31 when building my M16A4 clone. I like everything about it, except the short eye relief. (Well, almost everything... ironically I have just located some foreign matter in it after a year of owning it, so its going back to get cleaned out... I understand this is very rare though) So, I'm still thinking about an optical sight for the XCR, and am considering a TA11F.

A couple things give me pause; that being it was designed for a 20" barrel, and an AR15 height over bore. How far off would this put me with it on the XCR? How about when switching calibers?

Bullet weight and velocity make sense, but I'm having a hard time visualizing how the height over bore really has a big effect on the recticle pattern.

 

[dont_tread_on_me]

The height over the bore isn't a big deal if it's a standard scope you mount and sight in.However if a scope is calibrated for a specific bullet/cartridge combination and is designed with a specific distance from the bore in mind,it will effect the range markings on the scope.
In other words if you have a 100/200/300 meter/yard marking,then they won't be at the exact range they are set for.By how much depends on the difference of how much more or less the optic sets off the axis of the bore.
The velocity loss from the shorter barrel is enough to throw it off even more I would think.I'm fairly certain my logic on this is sound.

 

[SigsRule]

I switch my TA31 between my XCR and my FAL without problems. Since I wear glasses anyway the eye relief isn't a big or notable issue. I checked the ballistics tables and there's not enough difference at normal ranges to worry about. Get the TA11, you won't regret it.

 

[EricCartmann]

i owned a TA01, extensively shot a TA31F, but nothing compares to a TA-11.

no acog is faster for getting a proper sight picture. that long eye relief does truly make it easier to sight in... i love it so much I plan to get another one, a TA-11E for my AR10.

 

[MrSmitty]

I was thinking of buying an ACOG later on. Right now I have 2 Elcan Spector DRs one calibrated in 5.56 and one in 7.62. But I will need another scope in the future for some new rifles I should be getting the next 1-2 years. I was thinking the TA648 for one of the 7.62 rifles I will have.

 

[ny32182]

So if I were shooting, say, M193 from the XCR (which I read is the ammo that the TA11F is calibrated for from a 20" flat top AR), does anyone know how far off each of the range markings would be, in theory at least?

 

[dont_tread_on_me]

You need a ballistics program ,that can also allow for hight from bore.You may be able to find one online that's free.

 

[EricCartmann]

It is about 100fps difference between 20" and 16" so up to 600 yards. Difference is really negliable.

Up to 300 yards you are talking fraction of inches

@ 400 yards it is only 2 inches

@ 600 yards it is only 4 inches

@ 800 yards it is like about 10 inches

We are talking inches here, so you can pretty much aim dead center up to 600 yards, at 800 just aim for the head. ;D But then again, at 800 yards it is really not going to matter as windage can be very tricky at that distance, this goes for all scopes and all distance shooting. Unlike bullet drop, wind is very unpredictable. It could be 15mph to the right where you are standing but 0 mph downrange. It can come and go just like that.

You can use any ACOG for any rifle, you just have to learn the particuliar BDC and how it affects your rifle. BDC is just a questimation anyways. Also it is not like targets will be exactly 300, 400, or 500 yards away or your range guestimation will always be spot on.

Here is what my XCR looks like with a TA-11F. I since moved this optic to an AR.

 

[ny32182]

Thanks for the info guys; nice pics Cartmann. The body of that thing appears to be significantly longer than that of a TA31.

Sounds like the barrel length will be fine for my purposes then... do you know how the height-over-bore plays in?

I guess I should get a ballistics program sometime.

 

[ny32182]

Also, do you know if it can use the same LT100 mount as a TA31?

 

[dont_tread_on_me]

Here is an online ballistics calculator...http://www.eskimo.com/~jbm/calculations/traj/traj.html....If I had all the parameters I could have done it more precisly for you.

A 55 grain 224. bullet driven at 3250 fps optic placed 1.5 inches over bore http://www.eskimo.com/~jbm/cgi-bin/jbmtraj.cgi

A 55 grain 224. bullet driven at 3150 fps,optic placed 2.5 inches over bore http://www.eskimo.com/~jbm/cgi-bin/jbmtraj.cgi

As you can tell it's not a significant differance,but you won't be able to aim for the skillet at 800 yards,as the bullet drop is somewhere around 20 feet

 

[EricCartmann]

it's 20 feet from dead center, what we are talking about is the 800 yard BDC hash mark on the TA-11F. It will be 10 inches off from that.

 

[dont_tread_on_me]

I knew what you meant,I was just yankin your chain a little.

 

[EricCartmann]

Thanks for the info guys; nice pics Cartmann. The body of that thing appears to be significantly longer than that of a TA31...

yeah it looks kinda awkward the first time you see it, but the longer ACOGs actually grow on you and eventually you will think all ACOGs should look like that.

Below is how the a TA11F and a TA01NSN (same body as the TA31F) compare side by side.

 

[ny32182]

Well I just ordered one. We'll see how it goes ... Actually I bet it will be here before my TA31 gets back from Trijicon.

The XCR will finally have some decent glass on it.

 

[ny32182]

Its here. Looks nice. Now if my lower would just get here I could go shooting tomorrow.

 

[TEXAS SOLFTAIL]

THAT WAS FAST, DID YOU GET IT OVER NIGHTED?

 

[ny32182]

It took four days from the dealer I ordered from...

I don't know if it is just me or what, but I've now had two of these things and both have had minor issues.... the chevron in the TA11 looks like this:

Since I have just bought it I think I will call the dealer on Monday and see if they will just exchange it for another one. I sent my TA31 to Trijicon recently after seeing some foreign matter inside the housing.

 

[SigsRule]

All I have to say is I'm jealous if you can actually see the black on the bottom of the chevrons. My 61 year old eye's have to look hard just to see the chevron clearly. That doesn't mean I can't see the Chevron and hit accurately with it, but to my eyes unless my glasses are perfectly aligned all I see is the orange point. But I checked with my best glasses and my Chevron is perfect on my TA31.

 

[ny32182]

It depends on the lighting and the background as to how apparent it is, but under the right conditions it is pretty obvious. My TA31 definitely doesn't look like that. Hopefully the dealer will take care of it for me.