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Thread: Zeroing a 9mm PCC, Strange Ballistics.

  1. #11
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    Unsolicited

    @Chomps

    This is unsolicited advice, feel free to disregard.

    I have a bunch of 8-11” MPX that I zero regularly.

    Ballistic calculators for pistols usually assume pistol barrel length and velocity.

    PCC can pick up 100-300 fps depending on the ammunition.

    If you’re going calculate ballistic drop, you have to chrono the ammo out of your barrel or find data from someone with a similar gun.

    My procedure for zeroing:

    1. Wheeler laser to get optic close at home. I usually try and match it up at about 20 yards or so with the laser.

    2. Go to range and get the most rock stable rest or position I can possibly get. I have a couple of really SOLID rests that don’t allow any wobble. And I pin myself into a corner so I’m not wobbly either.

    3. Use 2” round pasters on a clean sheet of copy paper.

    4. At 7 yards, I’ll take a shot and adjust windage to try and get dead on. Will also try and put the elevation to impact about 1-2 inches low. If the shot is at center or higher, I dial it down or else it’ll definitely be too high at distance.

    5. Then I’ll move the target out and take a few more shots. But call each shot. If you have a bad press, ignore that impact. I’ll usually take a couple at 15, but dial elevation down if any shots are at or above center. At that distance on the 2” circle, if your aim is dead on the impacts should be just towards the bottom of the circle.

    6. Then I’ll move out at 25 yards and take 3-5 of the best trigger presses I can muster and then check the target. If they’re reasonably clustered around the center, I’m done. If not, adjust and repeat.

    A modern gun should be able to do a 2” group, so do your part.

    For something like a self defense gun, I’ll do all the steps with training ammunition of similar velocity to the carry ammo. Then just 1-2 shots at the end to confirm.

    Typically if I have a good rest and good trigger presses, I can get the whole process done in under 10 rounds.

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    Last edited by JCN; 10-26-2022 at 09:49 PM.

  2. #12
    Quote Originally Posted by Chomps View Post

    For the record,.. technically, this is a pistol. Not a “long rifle.” It’s a Foxtrot Mike, 9mm AR. PCC with a 1:10 Twist, 10” barrel.

    However, I was not using a pistol calculator for my bullet drop calculations. (…it was some online ballistic calc I found.) It did have a section for height over bore for the sights & IIR,.. I used 2.5” or 3” since the AEMS Holosun sight sits very high.

    I figured since it is technically a pistol, and intended as a PDW, that a closer zero would be somewhat preferable. My thoughts were,.. “Zero it @ the desired up close distance,.. then document where my POI landed at various other distances,.. and adjust my hold over accordingly.”

    Full disclosure,.. I’ve changed zero a couple times. Initially, I tried different zero distances. One of which was 25 yds. IIR, My first zero was @ 10 yds I believe. And my precision and accuracy was much better. (…pretty much punched out the bullseye). Im not sure why I decided to change it. But I decided to try a 25 yd zero. Unfortunately, Between my astigmatism and poor distance vision,.. Even with my glasses, I just wasn’t happy with the results. I can’t recall my exact objection, But POI and grouping @ different distances wasn’t what I hoped. So I went back to using a closer zero and settled on 15 yds.
    .
    I think you might want to review what zero means and what you're trying to do. You've gotten some good advice, might want to slow down and take a look at what people are trying to tell you and make sure you understand.

  3. #13
    Site Supporter rob_s's Avatar
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    Sorry if I missed it in the wall of text…

    What’s the use case for this gun again?

    Somewhere I have a thread here about zeroing a PCC for competition purposes (I think, Ayre I’m also remembering wrong.

    IMO you should “zero” for your intended purpose, understanding that “zero” is your second intersection and what most people “zero” a pcc for is the initial intersection.

    Fwiw I like to zero real carbines at the peak of the ballistic curve so I’m only dealing with hold-overs, never hold-unders. I don’t do the same for pcc

    Also it’s worth noting that a drift right or left as distance increases is a common problem. It means you aren’t really zero’s for windage at your initial intersection, you just think you are. As distance increases the error becomes more evident. Set your windage at the further distance.
    Does the above offend? If you have paid to be here, you can click here to put it in context.

  4. #14
    Site Supporter rob_s's Avatar
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    Does the above offend? If you have paid to be here, you can click here to put it in context.

  5. #15
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    Quote Originally Posted by rob_s View Post
    …understanding that “zero” is your second intersection and what most people “zero” a pcc for is the initial intersection.

    Fwiw I like to zero real carbines at the peak of the ballistic curve so I’m only dealing with hold-overs, never hold-unders. I don’t do the same for pcc
    “Maximum point blank range” is a great concept and I like that very much.

    With a 150gr pistol cartridge going at around 1000-1100 out of a PCC that top of the curve is around 35 yards… but 25 yards is pretty close to the plateau and it doesn’t rise much after that point. Useable plateau out to 80+ which is about as far as I would ever use in competition (or realistic self defense in my location) so I would be good with that.

    Plus, when you take into account the types of targets, speed requirement and distance… a plateau +/- 1 inch at 25-80 yards is going to be well within noise of movement and skill for any kind of time requiring use.

    A 25 yard zero for a slow bullet puts you less than 2 inches low even at bad breath and narrows to 1 or less across a hallway. Aim for the high thoracic and hit the lower high thoracic. Aim for the eyes and hit the face.

    What I DON’T want is to have to worry about sending rounds OVER their head so a rising zero is much better for me in a self defense zero.

    That’s just me personally.

    Also FWIW from the other thread you linked, I was using an X95 in that thread with an extreme height over bore.

    Now with MPX and JP5, I can zero at the center dot and use the bottom ring of the reticle close up for holdover.

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    From 25-80 yards I’m not accurate enough to worry about the 1 inch rise to full peak.
    Last edited by JCN; 10-27-2022 at 07:57 AM.

  6. #16
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    Quote Originally Posted by MickAK View Post
    I think you might want to review what zero means and what you're trying to do. You've gotten some good advice, might want to slow down and take a look at what people are trying to tell you and make sure you understand.
    Which is EXACTLY why & what I hoped to accomplish by posting itfp! Understand, Im not being sarcastic, flip or dismissive,.. but what is it that you believe I “don’t understand” about what Zero means?

    I thought “ZEROING” meant that you adjust your sights/RD so that your POA/POI intersect at a chosen distance. If I’m wrong or have missed something basic about that process or definition, please inform me. That’s what I’m here for. Im new to ALL of this and Im sure I misunderstand and get stuff wrong all the time.

    Also,…. I am most definitely paying attention to the advice being given. I’ve bookmarked most of it and as I already mentioned, I intend to attempt to fix, and re-do the entire process this weekend to see if I can correct those High/Right Hits!


    Quote Originally Posted by rob_s View Post
    Sorry if I missed it in the wall of text…

    What’s the use case for this gun again?

    Somewhere I have a thread here about zeroing a PCC for competition purposes (I think, Ayre I’m also remembering wrong.
    Ok, first,.. Thank you for the link. I appreciate the additional information.

    Second,.. in this case, I am being just a little bit flip,… 🤣😉
    …I object to the characterization of my post as a “WOT!” It has paragraphs,.. it has punctuation,. Obviously not CORRECT punctuation, but it HAS punctuation! I regularly annoy the HELL out of the Grammar Nazis online!! 🤣🤣🤣. (The only subject I sucked worse at than math? Was English composition! LOL)

    If anything,.. I feel my post falls under the category “TL;DR!!” 😉. As for that,… I’m just trying to be thorough and basically,.. I’m a long winded SOB! Lol

    And thirdly,… To address your second point, what you may have missed in my TL; DR post was that this weapons intended use is as a PDW. Not for use in competition. Hence my thinking a closer Zero might be preferable. 🤷

    I keep reading (…online reviews, YT vids, etc.) that 9mm, and shorter Pistol build type PCC’s are not intended to be long distance shooters. Altho some of these guys appear to be getting good hits @ 100-200+ yds,… so I was trying to focus more on accurate, Up Close sighting than anything else. My confusion was, and still is, created by experiencing having those rounds continue to Rise & hit Higher & Higher @ Distance, instead of dropping as I expected them to do!


    I agree with @JCN regarding NOT wanting rounds to get lobbed over the intended target and risk a potential hit on unintended people, places or things!! THAT is DEFINITELY something I desire to avoid.

    It’s obvious I need to research this subject a little further. Again,.. I appreciate all the feedback!

  7. #17
    If you’re still confused about the high/right hits, we probably aren’t explaining things well enough. The ballistic calculator you’re using to estimate what your bullet should do in relation to your line of sight is only accurate if all of the data input is accurate. Garbage in = Garbage out. The calculator is based on having a perfect 15y zero and exact numbers for bullet weight, velocity, ballistic coefficient, etc. You don’t have a proper 15y zero because your rounds are impacting about an inch high and right compared to your POA, which I’m assuming is the tiny dot in the center of the target from your posts. You have a near zero (where the path of your bullet first crosses your line of sight) for a distance, but that distance isn’t 15y. If it was 15y, your rounds would be impacting exactly into your POA.

    Also, the optic adjustments in minute of angle (MOA) are fixed at whatever the manufacturer set them at. I’m going to use 0.5 MOA for ease. I don’t know if that’s what your optic actually does. At 15y, 1 MOA is approximately 0.15” and 0.5 MOA is something like 0.075”. If you’re an inch off to the upper right from your POA, that’s like 7 MOA at that distance. That’s 14 clicks if each click is half an MOA. An MOA is an angular relationship so once you start backing off to 25y, 7 MOA isn’t 1 inch anymore. It’s 1.75 inches. At 50y, 7 MOA is 3.5”. It’s also easier to make exact adjustments at farther without overshooting or undershooting your intended POI. If each click at 15y is 0.075”, how easy is it to get the exact perfect amount of clicks you need? At 50y, it’s easier because each click is 0.25” at half an MOA and that’s a number most people can understand and visualize more easily (again, assuming your optic has 0.5 MOA/click adjustments). That’s why many people looking for an exact zero will make windage adjustments at the farther ranges even if their zero is closer than those distances.

    ETA: here is a photo of a couple of groups with my APC9 Pro, a similar firearm. It’s a 9mm with a 6.8” barrel. I zeroed at 25y with Speer Gold Dot 124gr +P. At 25y, things looked dead on but it’s hard to judge fractions of an inch that small. Here is a group fired at 50y and a group fired at 100y. Both groups looked a smidge to the right so I adjusted 1 click (05. MOA for my optic) which should move the 50y group 0.25” to the left and the 100y group 0.5” to the left. I’m satisfied with that. At the zero distance of 25y, I wouldn’t have noticed anything if I moved the zero one click because at that range one click is about 0.125”.

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    Last edited by WobblyPossum; 10-27-2022 at 09:55 AM.
    My posts only represent my personal opinion and do not necessarily reflect the opinions or official policies of any employer, past or present. Obvious spelling errors are likely the result of an iPhone keyboard.

  8. #18
    Quote Originally Posted by JCN View Post
    1. Wheeler laser to get optic close at home. I usually try and match it up at about 20 yards or so with the laser.
    I'll be damned, I had no idea such a thing existed and it's on sale. Ordered.
    #RESIST

  9. #19
    Site Supporter CCT125US's Avatar
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    @WobblyPossum nailed it and saved me from typing alot.
    Taking a break from social media.

  10. #20
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    Quote Originally Posted by LittleLebowski View Post
    I'll be damned, I had no idea such a thing existed and it's on sale. Ordered.
    You know I buy everything in order to test everything.

    This was one of those things that exceeded expectations even though I thought it was going to be cheesy.

    Mine is consistently a couple MOA to the left but again, consistent.

    The ability to use it no matter the caliber is awesome.

    It’s good enough that for close up stuff I sometimes don’t even zero live if no chance. It’s also a way to spot check if your mounts have shifted.

    I liked it so much that I recommended it to others like GJM who is now a super fan.

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