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Thread: Really [dumb idea] short eye relief ACOG

  1. #1
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    Red face Really [dumb idea] short eye relief ACOG

    A few years ago I picked up a compact ACOG TA-50 in a trade, and I’ve been trying to figure out what to do with it ever since. I like everything about the sight except the phenomenally short eye relief: 1.4” What was Trijicon thinking when it designed this 3X scope?

    It usually winds up on one of my range rifles, almost always on a Franken-rifle one that has other parts I am experimenting with. It is fine for that purpose, but the short eye relief is a pain. It barely works as a CH scope with a collapsible stock. Mounting it in front of a BUIS (I insist on a backup) takes away at least two slots, usually three, on a flattop. (The only way to shorten the spacing to two slots is to raise the scope and chop the mount, and those mods bring their own problems.) But, what if I placed the ACOG all the way to the rear?

    I have two questions: (1) Why did Trijicon design this thing with such short eye relief and without mounting it to the rear as with the TA-31s?

    (2) Although I am probably not the first (or the last) to do this, is there anything really wrong with the setup below (backup in front of the ACOG and backward)? Both the Magpul MBUS and the ACOG are boresighted and I plan on taking it to the range in a few days. I would like to get the consensus of the M4C crowd. Being laughed at is not big concern.

    Last edited by Amicus; 04-06-11 at 15:33.
    'That whole effort was held together by sweat, shame, and a tiny bit of pride.' -- Son of Commander Paisley

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    Sell it.

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    Without having tried it, I'd question whether or not the aperture on the MBUS is okay to be used backwards. Pretty sure you'll have no problem, but it'll take shooting to confirm that. Front MBUS, backwards is no impact, but that's not germane.

    Does it only fit under the objective if backwards? Since you'd have to ditch the ACOG annyway, that's the only reason I can think of to mount it backwards.

    If you had a mount that required a tool to remove, I'd opine that there's little point having a BUIS at all. Not the case, here.

    Other than that, if the eye relief gigs you, I'd also say to sell/trade it.
    Contractor scum, AAV

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    How 'bout $50.00 for the ACOG?

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    Quote Originally Posted by Scotty View Post
    How 'bout $50.00 for the ACOG?
    That's the price for the MBUS. The ACOG costs a bit more.

    The TA-50 is not really a problem. It just has shorter eye relief than I would prefer and, once one finds a usable setup (stock length, mount, sight placement on the upper), it's use in unconventional or expedient shooting positions is less-than-optimal. On the whole, its advantages outweigh its disadvantages, at least for me.

    Also, the sight sits upon a shortened ADM QD mount which will permit rapid removal of the sight if necessary. Whether placed before or behind, the flip-up will be unusable, unless the ACOG is removed, due to the 3X magnification.

    With this in mind, the anticipated problems with mounting the MBUS (or, BUIS, I've tried several from the box o' spares) forward of the sight are:

    1. Shorter sight radius -- obvious.
    2. Many apertures have concave surfaces around the aperture that can distort the image or create a reflective "ring" around the aperture that can be distracting. (NOTE: There does not appear to be a lot of rationality involved here; with normal use, some manufacturers have a concave surface facing the shooter, some do not.)
    3. The increased distance from the shooter's eye to the rear sight effectively shrinks the size of the aperture. Both apertures are usable, but a small mental adjustment will be necessary.

    Have I missed anything?
    'That whole effort was held together by sweat, shame, and a tiny bit of pride.' -- Son of Commander Paisley

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    As a NTCH shooter I, as in 'me', find compact ACOGs work well when mounted on a detachable carry handle.
    Familiarity breeds contempt -- and children.

    Mark Twain

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    Damn, that ACOG is so sexy...

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    Quote Originally Posted by LettersFromEarth View Post
    As a NTCH shooter I, as in 'me', find compact ACOGs work well when mounted on a detachable carry handle.
    LFE: With the exception of this model, I would agree wholeheartedly. If I had not just boresighted the scope for a range trip I would illustrate the problem. (Maybe later this week.)

    Simply put, the TA-50 works well in a "normal, right in front of the BUIS" position on a flattop, but my nose better be right on the CH to get optimal eye relief. If I have to assume an odd position, or use an A2 stock or a collapsible stock extended beyond NTCH lengths, then the unforgiving eye relief is a pain. In the position pictured, it is too far back, but just now I am trying to figure out problems with mounting a MBUS/BUIS forward of the optic.

    Optimally, I am trying to configure this scope for use with an A1 stock. In the end, I will probably put it back in its "normal" configuration, but I would prefer it to be placed one slot further to the rear. Problem with that? I must either raise the sight about 1/2", or, machine off part of the ACOG base, or, extensively modify the back up sight.

    Without trying to open up a can of worms, I will say that I am a bigger fan of this scope than of the TA-33 with chevron.
    'That whole effort was held together by sweat, shame, and a tiny bit of pride.' -- Son of Commander Paisley

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    You could drill another hole (further back from the primary one) in a CH or maybe consider... Hell, I don't know. Good luck finding a solution(s) and please keep us posted.
    Familiarity breeds contempt -- and children.

    Mark Twain

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    http://www.snipershide.com/forum/ubb...Number=1086608

    http://stores.homestead.com/Laruetac...ail.bok?no=244

    Might want to take a look at this mount.

    It won't be the prettiest, but it'll get the ACOG back a little further.
    "Life is short, but the years are long." - Robert A. Heinlein

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