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Thread: Open letter to BDC designers

  1. #11
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    The problem here is expectation management. You and the manufacturer’s have two different standards of accuracy. The manufacturers and .gov are satisfied with minute of man at those distances.

  2. #12
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    I'm re-visiting this thread.

    Based on 1168's threads here and on other LPVOs, I've endorsed the Steiner P4Xi to a number of young kids shooting the M4A1 with M855A1 (the new Army 5.56 round) to get the flexibility of both an ACOG and Aimpoint in a single scope. When I reload for my kids and we shoot ACOGs, since we don't have access to M855A1 when we're not working/training on Uncle's dime I load 69-grain Tipped Matchkings or regular 69 Matchking BTHPs to match trajectory.

    I like quick, and I like a generic BDC that'll kill an E-type, but most of all (for new shooters) I like simple. 1168's technique to zero at 200 and follow the BDC (against GI E-types) works like a charm.

    I'm feeling inflation pressure -- our local gun shop has a P4Xi on the shelf for around $650.

    Here's a bit of good news: I found this article titled "The Convenient Overlap of M193 and the 77 gr Sierra TMK" < https://thenewrifleman.com/the-conve...gr-sierra-tmk/ >. You don't have to buy the more expensive T5Xi for the 7.62 reticle. This guy found (on Strelok) if he zeroed his 1-6 Vortex (JM-1) at 200 for the 77 TMK the BDC tracks with 55-grain M193 / commercial Ball zeroed at 100.

    This should also work with both the P4Xi and ACOG BDCs.

    Nice.

    The only problem is, if you're not independently wealthy you'll have to handload (if you can even find 69 or 77 TMKs). I'll bet you can get fairly close with other bullets, too, while we're in covid shortages.

  3. #13
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    So, I was eyeballing a Credo and saw the BDC model. Well, $&@%. 55gr. But then I looked at the drops in it. Distance in yards, drops in MOA. BCs from Litz.
    200 z
    300 3.3
    400 6.5
    500 10.7
    600 16.1
    Well, that looks familiar. So I punch 77SMK, 2600fps, 3” optic height into my calculator.
    200 z
    300 2.9
    400 6.6
    500 10.9
    600 16.1
    Neat. How about 69 SMK @ 2700fps?
    200 z
    300 2.8
    400 6.3
    500 10.7
    600 16
    Sweet. This is really close also to the 7.62 T5xi. Crank it up to 2850fps, and its nearly spot on to 600 in the P4xi. I’m guessing Sinister is somewhere in that range, or maybe a little slower with the TMK.

    For further nerd joy,
    M855 @2800fps with the same 3” height
    200 z
    300 2.6
    400 6.1
    500 10.4
    600 15.8
    Of course, precision and wind isn’t great at that point. How about 2900 fps?
    200 z
    300 2.4
    400 5.6
    500 9.6
    600 14.5
    A little flatter…could use either the 7.62 T5Xi or the P4xi successfully, especially at 500 and in. I’ve also been looking at the ACSS M2 on the PA Platinum 34mm LPVO:
    200 z
    300 3
    400 6
    500 9.7
    600 14.2
    Looks like with a 14.5” and M855, it should be on. It would also be perfect for heavier match ammo from a 16” or 18” barrel. Here’s 69gr 2850 fps:
    200 z
    300 2.4
    400 5.5
    500 9.4
    600 14
    And 77gr 2700fps, still with a 3” high optical HOB:
    200 z
    300 2.6
    400 6
    500 10
    600 14.7
    ACSS or 7.62 T5Xi will work nicely.

    There’s no real point to this post, but, I crunched the numbers and wanted to share the data output. Keep in mind with all of this, wind is a thing. The ACSS has dots for 5mph that math out fairly reasonably with the above loads. Triji and Steiner do not.
    Last edited by 1168; 10-15-21 at 11:18.

  4. #14
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    Excellent post! I played with some of the same numbers concerning the Credo. If it's there long enough I'll probably want it.

  5. #15
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    Quote Originally Posted by opngrnd View Post
    Excellent post! I played with some of the same numbers concerning the Credo. If it's there long enough I'll probably want it.
    The BDC is appealing, but I need to get one in my hands to look at the illuminated portion before I pull the trigger. The PA looks like the center is more usable up close, but it is listed at an absurd weight.

  6. #16
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    Shot the PA PLX 1-8x ACSS yesterday. Zeroed it at 300yds with Frontier 68gr through a suppressed 14.5” Noveske. I made a few adjustments and then shot a 5 shot group centered about an inch or so high. Figured that was good enough and moved to steel at 200, 300, 400, and 480. It was pretty close, just needing to hold a little low on the 400 and 480 (using the 500yd hash). Obviously, I need to adjust it a bit and play with it on paper, but it looks like it might work pretty well.

  7. #17
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    Quote Originally Posted by 1168 View Post
    Shot the PA PLX 1-8x ACSS yesterday. Zeroed it at 300yds with Frontier 68gr through a suppressed 14.5” Noveske. I made a few adjustments and then shot a 5 shot group centered about an inch or so high. Figured that was good enough and moved to steel at 200, 300, 400, and 480. It was pretty close, just needing to hold a little low on the 400 and 480 (using the 500yd hash). Obviously, I need to adjust it a bit and play with it on paper, but it looks like it might work pretty well.
    Does it still have that RCO-M4 ACOG feel to it, or does 8x magnification give it a more traditional scope feel?

  8. #18
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    Quote Originally Posted by opngrnd View Post
    Does it still have that RCO-M4 ACOG feel to it, or does 8x magnification give it a more traditional scope feel?
    At 8x, it feels more like a traditional scope, for sure.

  9. #19
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    Quote Originally Posted by 1168 View Post
    so it should work, right?Kinda like the existence of 7mo NREMTP accelerated courses.

    I laughed WAY to hard at this...... considering the quality of EMT and EMT-P's that are coming out now a days.

  10. #20
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    Quote Originally Posted by jwfuhrman View Post
    I laughed WAY to hard at this...... considering the quality of EMT and EMT-P's that are coming out now a days.
    Yup. The schools offer accelerated courses because they sell. The students sign up because they assume that the school has determined that this is an adequate amount of time for the material. If I ran NREMT……

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