Bullet Getting itself together!!

[Randy in Va]

We all know people that claim a particular load shoots poorly at 100 and magically gets it s**t together at 300, 500, 1000 etc and gives a tighter MOA.

I say horsefeathers and want to know if somebody can defend this with science.

A bullet impacting at 1000 has a start (end of gun barrel) and an obvious ending. The arc between them is theoretically determined by observation at closer ranges and software based on bc, altitude and a few other factors. I contend that if I could shoot through tissue paper held taught every 25 yds, that the holes would be on a single arc and that the only difference between them would be the shape of the hole. They would be perfect holes at the end if we computed right and less perfect as you go toward the shooter. The bullet traveling this arc might not be perfectly stabilized and thus produce less than a perfect hole. I would concede that because of changing BC's this arc might not be completely linear.

What I am having trouble conceding is a bullet off the vertical plane that pulls itself magically back on the intended path.

FLAME SUIT ON! Make me a believer.

 

[Kevin]

I know what you are talking about. This is just my opinion, and what I have observed, so make what you want of it.

In my 220 swift AI, 16 twist, I shoot a 55gr BT or 55gr. V-max at about 4250fps. At 100 yards my average group size is only 1.25 inches. If I move back to 500 yards, groups are no greater that 4 inches and often less, around 3 inches. Based on the 1.25 inch 100 yard groups my 500 yard groups should be over 6 inches. (glad they are not)

I believe that these bullets are just on the verge of being stable and right out of the muzzle get kicked slightly to one direction or the other then continue on a parralell path relative to the barrel direction.

So call BS or what ever you want but thats my .02. Other opinions welcome.

 

[Randy in Va]

I know there are many that say the same thing. I just am having trouble explaining it!!

 

[ackleyguy]

Well a bullet that leaves the bbl with a bit of pitch and yaw (all do) usually stabilize pretty quickly before 100 yds... Not always though..... but does it take 300 yards to stabilize...not likley...alot of times guys will shoot better groups at 200 than 100...why??
Well one of the reasons is they are not shooting a parallax adj scope...and its as close to parallax free at 200 as its going to get...now if you have a P/A scope well then it may be a matter of bullet instability at 100... mostly you will see this with a borderline twist or bordeline velocity for a given twist- a vld bullet...just my 2c worth

 

[Randy in Va]

Ackley guy,
Now we are getting somewhere. I will accept that until somebody gives me a better one!

See I'm EASY!!

 

[Guest]

Many scopes do not have accurate markings on their parallax adjustment, so I think Ackley brings a valid point which hints at the same issue for both fixed and variable power scopes. Bullets do have a fast and slow precession that does damp out at different points, but this does not affect accuracy unless the bullet is borderline to unstable (I would contend that borderline is unstable).

I have never seen a properly machined and bedded rifle with high quality bullets and a solid scope and mounts shoot worse at closer range, I will be a believer when someone tests this on a rail gun with over 30 groups shot at each range under valid conditions.