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Can one brand of ammo shoot left when other brands straight?


alexmg

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I went to range today to sight in new adjustable sights and came across weird issue. I can't quite understand if this is me doing my part wrong or indeed some brands of ammo can shoot slightly to the side when other brands straight.

I had 4 brands of 9mm ammo on me, 1 box each: two boxes shoot very straight, pretty much dead center at 5, 7, 10, and 15 yd (those are may comfortable -ish distances, anything after that I would not trust my groupings) well, of-course at 15ys shots are slightly above center, but horizontally they still centered.

Two other brands hit target about one inch lower left at 5 and 7 yd and so on at further distances, this ammo is also hotter than first two brands.

I know depending on ammo, its velocity etc... shots can hit target at different heights, for example if one brand of ammo hit target dead center at 15yd, other brand can hit it 1" above etc... But not sure that it can drift left or right unless I jerk the trigger or do other trigger error on my side.

Is it ammo or is it 100% me?

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Maybe a flinch in anticipation of the greater kick/report/flash of the hotter loads? If that's the case, the first round of a group of the hotter ammo might not show the flinch, and the rest might reflect what you expect after the first round is fired.

Try mixing a couple rounds of the hotter stuff into a mag of the milder load, loading without looking so you don't know the order. That way you won't anticipate greater recoil with any one round fired. If they all group together, it might be you. if there is a smaller subsidiary group low left of the main group, then maybe it's the ammo.

Why the ammo might group differently that way I don't know.

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It's the grouping that counts. Heavier bullets or hotter loads shoot differently. If you question your shooting, benchrest shoot at 15 yds and check the results. You can also let a friend that you know is a seasoned shooter try the ammo out.

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I have documented proof of this phenomena. Commercial 115gr, groups right on target. 147gr Atlanta Arms, groups high left.

Solved the problem by reloading my own ammo and standardizing on a specific bullet, powder, and primer. Now I have a sweet shooting, itty bitty puff of smoke, dead on round - always.....

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Thanks everyone for suggestions and info, I did little scavenging over internet to see if there are other people with similar questions and just like you saying above it is a known phenomenon. I am having hard time understanding how that is possible for bullet to deviate left and right, assuming barrel crown is not damaged, but perhaps maybe different velocities can cause different unlock time, thus causing shots to drift left, etc. Anyways I was happy to find out that this is possible because, frankly, it was driving me nuts, I sighted pistol, made some super nice groups, then loaded different brand ammo and shots low-ish left-ish, hard to diagnose because it is a classic trigger jerking/fingers tightening symptom.

Well, with above being said, thanks everyone for input, I will all try to mix different brands of ammo together in one mag and see is that will cause group to be split into two sub-groups.

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I think that heavier bullets and/or higher velocity can make the gun twist in your hand due to the rifling twist. Remember we are talking small amounts of difference. I doesn't take much of a change to move the POI an inch or 2 at 25 yds.

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  • 4 weeks later...

as everyone has suggested there are multiple variables at play. I would say so long as your groupings are tight no matter which ammo you're shooting it would come down to you tailoring your preferred ammo whether hand loaded or production bought and shoot that.

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  • 1 month later...

I could see a slower bullet affected as there would be more time for "stuff" to happen before leaving the barrel. There could also potentially be more gas coming out of a land on one side, unsettling the bullet by pushing more on the base as it leaves the barrel.

Is that what happens? Dunno! Just a wag.

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With my current sight adjustment patterns are:

1. All 124 or 147grain subsonics go dead center

2. One particular brand of ultrasonic 115grain goes dead center too

3. Anything else that feel hotter and kicks more goes left, not low/left, but just left.

So my scientific conclusion is that either I know it and gripping gun tighter or slapping trigger etc..... or indeed there is an an earlier unlocking (or other phenomenon, which as stated above has been observed by others) with hotter bullet causing barrel to constantly point a bit to the left. I can be wrong, but that is what I believe in and my gun feels my believes.

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Nice video! Good work!

I'd like to comment on what could be happening..

Two things..

1- OAL is a big deal to accuracy in group size.

2- grip on gun is being Influanced by recoil duration/implulse, causing the gun to travel left in your hands. I say that because those groups are not as tight.

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Nice video! Good work!

I'd like to comment on what could be happening..

Two things..

1- OAL is a big deal to accuracy in group size.

2- grip on gun is being Influanced by recoil duration/implulse, causing the gun to travel left in your hands. I say that because those groups are not as tight.

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