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Thread: point of impact changes with different ammo

  1. #1
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    point of impact changes with different ammo

    I've been shooting WWB and Federal for so long I can't remember the last time I shot something different. Like literally 3 or more years.

    So I decided to work through a case of 124 gr blazer brass that I've had laying around.

    This stuff is noticeably warmer than WWB and Fed Champion.

    However I noticed that I'm also getting impacts much higher than WWB or Federal at every distance. Its about 2" higher.

    I've switched back and forth on the same range session and POI is good with Federal and 2" higher with Blazer. Same gun, same range session, back to back to back.


    I wanted to see if anyone has had similar experiences either with 124 blazer or switching from low power ammo to higher power ammo. In other words is this an ammo issue or an expected outcome from shooting higher power factor ammo. The pistol used here is a Gen4 G19. It has about 12,000 rounds through it.


    FWIW when I shoot my gen 3 G22 in same range session, I don't get a POI shift (higher power ammo)...I was thinking this is a strange ammo issue.

    Either way its annoying...I have to aim at the very bottom of the square on a fast drill to have a prayer of keeping it in the 3x5 area.

  2. #2
    Site Supporter LtDave's Avatar
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    POI shift with different ammo is pretty common in my experience, even with comparable bullet weights. I've had POI shifts in every different direction, up to several inches. It is highly gun dependent. The only way to know with your particular gun and ammo combination is to test it.

    Also, changing bullet weight will almost always shift POI, generally the heavier the bullet, the higher it will shoot, unless it doesn't

    I was just testing ammo in a VP9 this morning. With several different 147 grain factory FMJ loads, POI varied between +2.5" to -1" at 20 yards with several shooting to POA. This gun consistently shoots 115 grain ammo 2.5 to 4" lower than the 147 grain loads. Some 124 grain FMJ loads shoot to POA, a couple are 2-3" low.
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  3. #3
    careful what you wish for blues's Avatar
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    Quote Originally Posted by LtDave View Post
    POI shift with different ammo is pretty common in my experience, even with comparable bullet weights. I've had POI shifts in every different direction, up to several inches. It is highly gun dependent. The only way to know with your particular gun and ammo combination is to test it.

    Also, changing bullet weight will almost always shift POI, generally the heavier the bullet, the higher it will shoot, unless it doesn't

    I was just testing ammo in a VP9 this morning. With several different 147 grain factory FMJ loads, POI varied between +2.5" to -1" at 20 yards with several shooting to POA. This gun consistently shoots 115 grain ammo 2.5 to 4" lower than the 147 grain loads. Some 124 grain FMJ loads shoot to POA, a couple are 2-3" low.
    I went to qualify with the sheriff's office last week and brought several magazines loaded with carry ammo as well as range ammo so that I had magazines filled with a mixture of 115gr, 124gr, 147gr, both standard and +P, FMJ and JHP. (Glock 26 and 19.)

    Despite the fact that POI was variable, my scores were relatively reasonable in that they ranged, (for each segment), from a high of 100% to a low of 96%. I never knew which ammo was coming up except when I started with a magazine loaded with carry ammo.

    I was curious how the mixture would effect my scores but was at least satisfied that it didn't have a huge impact in the final analysis.
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  4. #4
    Foppish Dandy Darth_Uno's Avatar
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    Not only common, but expected. You also don’t know exactly how much until you try it. You have all the physics involved with different bullet weights and speeds. And then factor in every gun’s slightly unique mechanics that might favor one bullet over another.

    I shoot mostly 124gr Fiocchi. 124gr Winchester hits pretty much the same POI as Fiocchi thru all my Glocks. Last week I tried some 150 gr Syntech and it hit several inches higher at 15 yds from one of my 19’s. It was much closer to the Fiocchi with one of my 17’s.

    So really, who the heck knows. Might be a lot with one gun, might be none with another.

  5. #5
    Site Supporter LtDave's Avatar
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    At most qualification distances where the majority of rounds are fired at 15 yards and in, given the generous scoring areas on typical LE targets, it probably makes no difference what ammo you shoot. Now that I think about it, I shot whatever ammo the department provided for qualification and never bench tested it to see the POA/POI. It didn't matter. Heck, we managed to qualify with the crappiest 38 reloads imaginable back in the prehistoric days.

    If you are going to try a 20-25 yard headshot, you better know your POA/POI.
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  6. #6
    careful what you wish for blues's Avatar
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    Quote Originally Posted by LtDave View Post
    At most qualification distances where the majority of rounds are fired at 15 yards and in, given the generous scoring areas on typical LE targets, it probably makes no difference what ammo you shoot. Now that I think about it, I shot whatever ammo the department provided for qualification and never bench tested it to see the POA/POI. It didn't matter. Heck, we managed to qualify with the crappiest 38 reloads imaginable back in the prehistoric days.

    If you are going to try a 20-25 yard headshot, you better know your POA/POI.
    I qualified with revolvers from 1983 through about 1996 (at which point they were just backups for several years.) I usually shot better scores with the revolvers early in my career.

    Yeah, at 25 yards I'm strictly shooting at center of mass...standing, kneeling and prone. My uncorrected astigmatism alone would keep me from chancing it. Closer in, depending on which gun, I'd feel much more comfortable.

    Back on the job we rarely had the same ammo from quarter to quarter during our quals. It was always quality ammo, but it could be any of several manufacturers or weights. The only thing that was consistent was that we qualified with carry ammo...never training ammo. Not changing ammo between several bullet weights, pressure and manufacturers (as I did last week) would definitely make a difference from shot to shot, however.

    I don't remember my scores varying a great deal back then unless I had a long night the previous workday.
    Last edited by blues; 07-14-2019 at 01:05 PM.
    “Tactics without strategy is the noise before defeat.” - Sun Tzu | "Everybody has a plan until they get punched in the mouth." - Mike Tyson

  7. #7
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    Thanks for the responses.

    I went back to range to work on simple marksmanship and a few other drills.

    I brought some federal, blazer 124, and some old hollow points that were laying around (115 gr, mix of golden saber, gold dot and critical defense)

    With extreme focus on lining up sights perfectly, I was able to get the blazer to shoot about an inch above POA at 25 yds. The Federal actually shot about 0.5 inch low. The mix bag of hollow points shot dead on POA. Ironically the blazer grouped the tightest by far...about 3".

    So with improved sight picture this difference was much less than I originally thought. However it took about 10-12 seconds between shots to get there.

    So then I switched to an RO Elite Springer with same ammo. The elevation differences were still pronounced but all ammo grouped much tighter. However it was still the same pecking order in group tightness (Federal>Hollow point mix>Blazer 124)

    This excursion has taught me a few things

    You need to shoot at least a few magazines of your carry ammo to see where it prints.

    Once you know where it prints, adjust accordingly--bullet weight, brand, power factor to get things lined up as close to POI=POA as possible.

    Different ammo can have different accuracy patterns.

    It is worth the time and money to find a practice ammo that is consistent in your pistol (and can replicate your carry ammo performance). Otherwise you'll be chasing sight picture problems (and other variables) that aren't really there--wasting time and money thinking you are doing something wrong.

    I like how consistently tight the blazer grouped, but its far enough off at 25 yds to annoy me and force a sight picture change during drills. Gonna have to deal with it until i'm through the case I have.

  8. #8
    In my experience, only the cheap ammo (like blazer) will produce POI shift when compared to higher end ammunition. Most higher end ammunition are very similar in POI, especially sub 25y.
    Last edited by voodoo_man; 07-16-2019 at 07:13 AM.
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  9. #9
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    With semiautos firing ammo reasonably close in bullet weight and velocity (for example, in 9 mm 115-124 gr at 1100-1180 fps) I've never seen large POI variations up to 25 m. The trajectoy of the bullets are quite similar, and the gun really recoils/rotates very little while the bullet is still in the barrel, most recoil is felt at the end of the rearward slide travel, when it hits the frame. I always tell my friends that shoot some rounds and want to touch the sights "shoot some more and the POI will be back".

    With revolvers up to 3" is normal, the recoil dynamics are quite different. The gun starts rotating up in your hand the moment the bullet starts moving in the barrel, and grip, gun weight, recoil impulse, and barrel time all combine to produce noticeable POI variations.

  10. #10
    POI shift is normal and varies between guns.

    My 19.3 has a much larger POI shift than my 19.4. Shifts aren't always predictable (i.e. 147 isn't always high, "hot" ammo isn't always high) but generally I see hotter and heavier ammo print slightly higher than typical 115. Even in one brand(Lawman for example) I'll have a measurably different POI between 115, 124, and 147. I'll also occasionally see shifts in windage, but not always.

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