rotational decay

[bruce m]

kurt, you have just discussed the yaw/overturning moment/spindrift thing in a different way.
I would like to add some comments.
firstly any spin stabilized bullet is in a condition of yaw due amongst other thing to its need to balance the forces of gravity, drag, and wind vectors.
looking for higher b.c. we lengthen the nose (ogive) and keep the shank the same.
this lengthens the bullet, thus requiring a faster twist to achieve stability, which in turn increases the yaw (of repose) and hence the angle of attack.
as long as the twist is sufficient the bullet will remain stable.
so we must allow for spin decay to have enough spin at the end of flight.
wind vector on the bullet changing suddenly (windshear) alters the balance of forces suddenly, which can upset the bullet.
this is overcome (at least partially) by increasing the spin more.
the longer the bullet, the faster the spin required, and the greater the angle of attack, or yaw.
when we talk these levels of yaw, the bullet holes in paper still look round, as the angles are quite low.
the nose high part of the yaw tends to be at a tangent to the arc of flight at any point in flight.
for a bullet not to do this it would have to be spinning at warp speed.
in a shoulder fired rifle, it is extremely hard to overstablize a bullet by spinning it too hard.
the 350 gn gould bullet will shoot well in a 45/2 7/8 with a twist designed for a 530 gn bullet.
where we get some forgiveness, the pressure on the nose (drag) becomes a lot less than at the top of transonic speed (start of flight) when it is subsonic.
this moves the centre of pressure in the bullet towards the base, closer to the centre of mass, thus shortening the overturning moment and requiring less spin for the same stability.
I am not worried about having to wind the sight up for elevation.
however when you wind the sight up less for the same weight bullet at the same m.v., it is losing less velocity in that flight.
less time in the air means less chance of a untoward thing happening.
it also means less wind deflection.
even the best can only guess/calculate wind deflection to a percentage of what it is.
the smaller it actually is, the same % error will be a smaller error.
over the years this will add up to a number of points on the scoreboard.
in a match it might add up to 1 or 2 points more on aggregate, which can be the difference in a place when you are at the pointy end.
bruce.

[desert deuce]

Music to my ears Bruce, music to my ears.

Those toe nail 6's at 12 o'clock and 6 o'clock that just barely cut paper last relay of the match at 1,000 yards are each six up, not each ten down

When the head on wind shears are battering the bullet in flight indiscriminately up and down 6's can be golden at the end of a string of record fire.

Keep this in mind, you are not the only one shooting in those conditions and as Yogi says, "It ain't over till it's over."

[bruce m]

well said zack.
it is NEVER over till it is over.
over the years you see an amount of evidence of this.
sometimes in aggregate matches, the winner never wins a range, just coming a consistent 2nd/3rd.
other individuals will run a blinder on one range and shitters at other ranges.
bruce.

[martinibelgian]

Lots of truth in that - One needs to get good scores over all distances to win or be in the points. Winning isn't about shooting 'perfect' shots, but rather about avoiding 'bad' shots. You don't really need the X's at long range, but getting them all on target when conditions are challenging is already a major contributing factor.
Don't forget, LR BPTR is one of the few sports where one can go from sheer exhiliration to total, absolute, dumbfounding headscratching in a single shot. That's the shot that missed the target, and you don't have a clue why.... And you're faced with the task of getting back on target.

[bruce m]

and there is always next time.
if you give up it will never happen.
the good ones are in for the long haul.
bruce.

[desert deuce]

Shooters that shoot half minute of angle groups at 200 yards should shoot those loads at further distances to discover the magic of Creedmoor.

Once one gets to 800 yards they begin to find out about the long range experience and once they have a load that will hold elevation at 800,900 & 1,000 they will begin to understand the thrill of long range shooting with a BPTR and reap the benefits of their hard work at load development.

However, what the rifle and load are capable of is frequently limited by the human element. This is where the evaluation and adaptation to the environmental conditions plays a critical role.

Generally speaking for both the self spotter and spotter situation there are three broad environmental conditions that may be experienced during a single match or relay for that matter.

They have been described as: Same conditions as last shot-hold center; mirage and wind increasing let's try to stay in the black; well Chucky if we can stay on paper we might just might win this thing. Shooting in the latter condition can have a dramatic effect on score.

At that point an X and a miss both are valued at ten points. A 6 and a miss, not so.

The secret I suspect is to learn to accept the conditions and don't give up because at that moment the conditions are the same for everyone on the firing line.

[mdeland]

What was a surprise to me is even at 600 yards in Midrange shooting you did really well to stay in the high 80's or low 90's as it seems something squirrely seems to occur to bullet stability in this portion of it's flight. Course target size is proportional to distance here as well.

[mdeland]

My guess is bullet is in top half of transitional zone.

[desert deuce]

Speaking of quantifiable terror, you should see how frightened an otherwise powerful bullet becomes when faced with the M65 target.

[mdeland]

I remember Garby one time talking about coming home from a Silhouette match he had done well in and on the way stopped to shoot a Schuetzen venue, then quipping about how humbling paper shooting was to is pride!

[mdeland]

Lots of folks reviewing Brent's video I'm thinking! Fascinating/jaw dropping motion picture for those interested in such things!