Thread: Accuracy at 100 vs 600 (example). Variations in accuracy at different ranges

I have heard of the term where a projectile or load settles down at distance and gets accurate where as it might not look that flash at say 100metres on paper. I have also heard the opposite, a nice group at 100 but opens up at distance and turns to rubbish. What is people’s experience with this?

My current 284 load seems to be the first example. It doesn’t do much flash at 100 but when I was shooting the gong at 575 yards it was shooting like a tack driver. I always thought it didn’t make sense?

My accuracy increases (relative to MOA) with my Sako85 at longer ranges, although i think its because at 500m im really focused mentally on shooting good but at 100m im complacent and my mind wanders.

I have read of 6.5x55 projectiles "going to sleep" over hundreds of metres.

I assume that means settling down into a very consistent stable flight resulting in high accuracy at distance.

Brian Litz has an article somewhere on this - basic gist was it is impossible physics for a bullet to settle down and get more accurate at range e.g be 2 moa at 100 yards and then 0.5 at 600

The theory is called epicyclic swerve. Litz initially touted this but later disproved it, in his opinion, by shooting thru a whole line of targets out to a considerable range and then measured the groups at each range. Found no evidence to support the old "projectile going to sleep".

However, I know of a top long range shooter in Oz who states (with back up theory) that you should never group test at less than 140 yards. Why 140 yards? Go figure.

https://www.longrangehunting.com/thr...swerve.148380/

I personally tend to shoot better groups at 200m vs 100m(moa wise) but I think that is more of a eye strain /lighting/parallax type issue.

Originally Posted by veitnamcam

I personally tend to shoot better groups at 200m vs 100m(moa wise) but I think that is more of a eye strain /lighting/parallax type issue.

I'm the same. Can be useless at 100m sometimes

Its not possible. A projectile cannot just alter its course mid flight (other than due to external factors, wind etc), as would be required in order for a projectile that was shooting say 1 inch at 100 to shoot better than that at distance.

Originally Posted by ChrisW

Its not possible. A projectile cannot just alter its course mid flight (other than due to external factors, wind etc), as would be required in order for a projectile that was shooting say 1 inch at 100 to shoot better than that at distance.

Thank you Chris, common logic prevails!

Originally Posted by ChrisW

Its not possible. A projectile cannot just alter its course mid flight (other than due to external factors, wind etc), as would be required in order for a projectile that was shooting say 1 inch at 100 to shoot better than that at distance.

In theory absolutely correct.
Practical, no projectile is 100% eccentric which means right at the start, when the centrifugal forces are high, the projectile yaws - and depending how bad it is, changes the course of flight. Later in it's flight, friction slows down spin and speed of the projectile which results in less centrifugal force so the projectile does settle down and it's impact becomes more predictable (better groups). Even later in flight, the spin is no longer high enough and the projectile starts tumbling - which again can change the course of flight. The US Artillery has a book which describes these effects on shells and projectiles and how to calculate it...

Originally Posted by JaSa

In theory absolutely correct.
Practical, no projectile is 100% eccentric which means right at the start, when the centrifugal forces are high, the projectile yaws - and depending how bad it is, changes the course of flight. Later in it's flight, friction slows down spin and speed of the projectile which results in less centrifugal force so the projectile does settle down and it's impact becomes more predictable (better groups). Even later in flight, the spin is no longer high enough and the projectile starts tumbling - which again can change the course of flight. The US Artillery has a book which describes these effects on shells and projectiles and how to calculate it...

Yes the military are the ones who really know this stuff and how to predict it. So in essence, a group that is dead on at 100 might strike left or right at 600. I understand it that if someone wants a dedicated 5-600 metre load, then the load should be developed at that range

Originally Posted by ChrisW

Its not possible. A projectile cannot just alter its course mid flight (other than due to external factors, wind etc), as would be required in order for a projectile that was shooting say 1 inch at 100 to shoot better than that at distance.

I would respectfully disagree. Projectiles may not get more accurate at distance, but they can certainly get less accurate. In the military, different calibre sniper rifles have different ranges they are guaranteed to make a headshot on, due to the different ranges that projectiles with different bc's and weights drop back through the sound barrier, as described above.

Also, many years ago for shits and giggles I would reload tracer projectiles out of 556 rounds into my trusty 222. With tracer burnout around 800m it was obvious that the 1:14 twist was not effective at stabilising long projectiles, as the tracer would arc gracefully out to 300ish, then scribe a weird helix about 50m dia till tracer burnout occured. Quite impressive to watch.

All of this seems to line up with what I always thought. The physics/math just never made sense to me.

The .303 Mk VII round was renowned for its lack of erratic flyers in the 500 to 900 yard area. The grouping consistency was better in that range than the shorter or longer ranges. Obviously the velocity/twist rate suited the projectile at that range, although the group sizes would naturally increase as the range increased. 10-12 inch groups were common at 900 yards, even better in some choice rifles, using aperture sights on tuned SMLE and No.4 target rifles. The 'sweet spot' for my scoped .308 No4 conversion was 800 metres giving very consistent performance with F4 ammo. My .30/06 long range rifle runs 0.5 MOA out to 200 metres but I haven't tried it on paper beyond that, just steel which is hit or miss.

i have experienced this also, put it down to the fact that i can see the 100m target to clearly and i tense up a little to try and hold the rifle still, at the longer range where i cant see the lines on paper i relax and don't over cook the shot