Poor accuracy at 300y, great at 400

[Mr. Magoo]

What targets are you shooting at? Stupid question and probably stupid suggestion but sometimes I just shoot at a target taped to a cardboard box or something. Is it at all possible your 300 yard target is moving around and your 400 isn't?

Again, very stupid suggestion I know…except I've done this…discovering that, even in a slight wind, it doesn't matter how steady I can hold IF THE DANG TARGET ISNT HOLDING STILL

No, we're good there..but it brings up a thing I've noticed for years that still makes no sense to me. When shooting at a target angled away to the right from you it will hit right of its normal poa. Angled to the left, it will hit left of poa. Can't wrap my brain around why it does that.

 

[Mr. Magoo]

How many shots total at both ranges? If so something else is going on. Erick cortina and alex wheeler talked about this on a recent podcast. From a pure accuracy and ballistics standpoint it's not possible.

I don't have alot of the ammo I plan on using on hand and it's a bit scarce so not that many rounds. I'm doing first shot, cold bore testing at each range 3 times. Groups are nice but realistically for hunting I need to know what the first shot is going to do.

I used to have loads of time for Reloading. Growing up sucks sometimes.

 

[Calvin45]

I used to have loads of time for Reloading. Growing up sucks sometimes.

My experience of it has been that you can either have the time OR the money to do the things you want to do…but never BOTH!!!

 

[Beluebow]

Unpossible.

Bryan Litz has a standing offer to anyone that will travel to his place and replicate this scenario.

 

[FireFlyFishing]

Hornady has a fantastic podcast regarding twist rates in rifle barrels. Highly recommend this podcast. In the podcast they mention bullet stability will INCREASE as it travels down range. I'm guessing this is what you are witnessing. The ELD bullets are very long and need fast twist barrels like the 7 PRC has. I suggest you go to a lighter bullet in the same make/model or try a more traditional bullet shape in that rifle. I'm guessing you'll have more consistent results at varying distances.



Also, stop trying to determine bullet drop without a chronograph. You're wasting your time. Output data is only as good as the inputted data.

 

[chav0_12]

My first question is; what's are the targets that you're shooting at? Size, shape, etc.

Do you have an anti-cant level on your rifle?

There's a really long thread on this forum about this. I can find it but it might take me a while. I'm not sure what it's called.

Here's a short one.

Better Groups At Distance

I have been searching for a rational reason that bullets wouldn't maintain a constant angular deviation between POA and POI as they travel down range. In other words, how could groups at say 600yds be smaller MOA than groups at 100yds? Initial, it doesn't make sense that a bullet could improve...

www.longrangehunting.com

 

[Phil Rizzo]

Unpossible.

Bryan Litz has a standing offer to anyone that will travel to his place and replicate this scenario.

If he's done it 2 times in a row, 3 ought to occur.
I'm eagerly awaiting

 

[xsn10s]

TL;DR
Do bullets have areas in thier flight path where they destabilize, then re-stabilize and become more accurate?

I have not personally seen this to such a degree in any of my shooting before.

Details:
I've been working on getting a browning a-bolt 7 mag, 1 in 9 twist, sighted in and trajectory mapped. Has a vortex strike eagle 3-18x scope that I pulled off my 308 and has proven rock solid on that.

Heres where it gets wierd. Rifle shoots a hair over moa at 100, 1.5 moa at 200, 2+moa at 300, and .5 to .75 moa at 400. Winds were 5mph and less.

My current life keeps me from having enough time to reload these days, so I'm using factory hornady 162 gr eld-x ammo. Chrono is on perma-loan so I don't know the exact speed of this stuff. Just using hornady data for now.

Not only is it shooting much worse at 300, but it is also shooing much lower at that range than it should. At all other ranges I tested is it right on the money elevation wise when using the hornady app and I was able to get multiple first shot, cold bore hits at 400 and 500 while practicing.

I played around with a bunch of different scenarios assuming my data was off but in no scenario I could come up with does it work out being that far off at 300 and right on everywhere else.

Do bullets have areas of instability that big?

I'd do a tall target test on on the scope and check how well the parallax works. My 2 cents from the peanut gallery.

 

[g7777777]

TL;DR
Do bullets have areas in thier flight path where they destabilize, then re-stabilize and become more accurate?

I have not personally seen this to such a degree in any of my shooting before.

Details:
I've been working on getting a browning a-bolt 7 mag, 1 in 9 twist, sighted in and trajectory mapped. Has a vortex strike eagle 3-18x scope that I pulled off my 308 and has proven rock solid on that.

Heres where it gets wierd. Rifle shoots a hair over moa at 100, 1.5 moa at 200, 2+moa at 300, and .5 to .75 moa at 400. Winds were 5mph and less.

My current life keeps me from having enough time to reload these days, so I'm using factory hornady 162 gr eld-x ammo. Chrono is on perma-loan so I don't know the exact speed of this stuff. Just using hornady data for now.

Not only is it shooting much worse at 300, but it is also shooing much lower at that range than it should. At all other ranges I tested is it right on the money elevation wise when using the hornady app and I was able to get multiple first shot, cold bore hits at 400 and 500 while practicing.

I played around with a bunch of different scenarios assuming my data was off but in no scenario I could come up with does it work out being that far off at 300 and right on everywhere else.

Do bullets have areas of instability that big?

Impossible if all other conditions remain the same. Wind is the most important variable

 

[MachV]

my quick answer is parallax

 

[Tiny Tim]

TL;DR
Do bullets have areas in thier flight path where they destabilize, then re-stabilize and become more accurate?

I have not personally seen this to such a degree in any of my shooting before.


Heres where it gets wierd. Rifle shoots a hair over moa at 100, 1.5 moa at 200, 2+moa at 300, and .5 to .75 moa at 400. Winds were 5mph and less.

Using point blank to 300 then dialing past that. It SHOULD be around 3" low at 300, but is hitting more like 6-7" low.

You guys are making me think this is a scope issue.

A little confused. My impression from your first post was about precision (group size measured in MOA). Then in post 14, it seems to be about accuracy (point of impact vs point of aim).

If it's the latter, I agree that it's your scope. No need to use your hunting ammo to verify that with a tall target test using various applicable settings for the ranges you expect.

 

[HSmithTX]

I'm going with parallax as well.

 

[Mr. Magoo]

A little confused. My impression from your first post was about precision (group size measured in MOA). Then in post 14, it seems to be about accuracy (point of impact vs point of aim).

If it's the latter, I agree that it's your scope. No need to use your hunting ammo to verify that with a tall target test using various applicable settings for the ranges you expect.

I know, typing hastily on my part causes confusion regularly lol.

I'm doing cold bore testing to see how close I can get to a bullseye at each range. Not only testing my rifle's ability to get them within the kill zone with plenty of wiggle room to spare, but also checking/ honing my ability to figure out where to aim and dial. You might say they do wind up being groups after its all said and done...but Im really shooting for score so to speak.

What i noticed after figuring out roughly where to aim with a ballistics app then verifying/ adjusting from there by actual real world testing is that at 300 yards, the variation from one bullet strike to the next (group size) was much bigger than at 400. Because of that, I could consistently get closer to my bulleye with each shot at 400 than 300 after i figured out where to aim, because it was shooting smaller groups at 400.

When i say i dont care about group size for hunting, what i mean is that what i really care about is how close i can consistently get to poi. You can have nice little .5 moa groups, but if those groups wander around the bullseye by a couple inches based on how you hold, temperature, or your mood .5 moa isnt really an accurate assessment of hunting accuracy.

The thing about this being a problem with my scope, is that it worked perfectly on my 308 2 weeks ago. Doesn't mean something couldnt have happened to it obviously and it's something I'll definitely check with handloads after hunting season.

 

[Dirtrax]

Shoot further and see if it falls apart. It could be barrel harmonics. Since you don't know the actual fps it follows that you don't know the ES/SD either. The "tune" so to speak may favor certain distances. It should fall apart at some point.