Nosler 7MM 168 LRAB elk performance report

[RockyMtnMT]

I didn't run drops out past 600 ( those were bad enough). But had I tried 800-1000, I couldn't have hit anything, maybe key-holing(?).
It was a discussion on here a few years back. A few of us suspected a bad lot number got out. Maybe not. I just lost confidence and switched back to my 180 Berger load.

Dynamic stability is a crazy demon.

 

[Fiftydriver]

Hey Kirby, we have run into the same thing but without a tip of any kind. I have a sneaking feeling you are running into a dynamic stability issue that shows up when higher velocity is hit. The longer for caliber a bullet gets the more likely you are too run into an upper speed limit that causes them to want to swap ends.

When we ran into it was when we did the 6.5 Ultracat running a bullet that was pushing 2" long in a 6" twist. On paper was pushing near 2.0 sg. Rifle was shooting solid sub 1" at 200y until we got 3200 fps or so and at 3300 fps had sideways impacts at 200y.

Maybe but i have shot through paper with these at long range and never have seen any hint of bullets tumbling. Always nice consistent round bullet holes…..

 

[RockyMtnMT]

Maybe but i have shot through paper with these at long range and never have seen any hint of bullets tumbling. Always nice consistent round bullet holes…..

If you pull the tip and shoot them do they stay accurate? Just a thought. If they aren't losing stability I wonder why they are losing accuracy? How much pressure does it take to push a tip into the nose? I'm wondering if one of the math guys can calculate how many pounds of force are created by the acceleration of the tip at the launch of the bullet? Not sure what a tip weighs, about 2-3 grains?

 

[BillLarson]

you cant ask for better bullet performance.....

 

[Bob Wright]

If you pull the tip and shoot them do they stay accurate? Just a thought. If they aren't losing stability I wonder why they are losing accuracy? How much pressure does it take to push a tip into the nose? I'm wondering if one of the math guys can calculate how many pounds of force are created by the acceleration of the tip at the launch of the bullet? Not sure what a tip weighs, about 2-3 grains?

A great Litz question! We used to test devices used in rockets that referred to as G- shock forces. Forces that could destroy a designed device at the max acceleration.
Way above my pay grade.

 

[Fiftydriver]

If you pull the tip and shoot them do they stay accurate? Just a thought. If they aren't losing stability I wonder why they are losing accuracy? How much pressure does it take to push a tip into the nose? I'm wondering if one of the math guys can calculate how many pounds of force are created by the acceleration of the tip at the launch of the bullet? Not sure what a tip weighs, about 2-3 grains?

no i have not pulled tips. My theory is that when the tips fall into the ogive, the meplat is deformed to varying degrees causing minute differences in yaw rate. Not enough to cause instability but enough to literally move the bullet off course inconsistently. This would also drop BC to varying degree causing the increased drop and drift i have seen.

 

[Fiftydriver]

I believe its simply the force generated by air resistence on the tip much more then the inertia of the tip under acceleration. The tips are very light but i feel its simply the increased force on the tip as velocity increases that is setting them back in the bullet. The trick is catching one to prove it somehow without causing any bullet deformation from the catching process. Have not been able to figure out how to do that…..

 

[RockyMtnMT]

I believe its simply the force generated by air resistence on the tip much more then the inertia of the tip under acceleration. The tips are very light but i feel its simply the increased force on the tip as velocity increases that is setting them back in the bullet. The trick is catching one to prove it somehow without causing any bullet deformation from the catching process. Have not been able to figure out how to do that…..

You and me both.

I think if you remove the tips the bc will suffer but accuracy will maintain. Shorter oal with better stability. No matter how fast you drive them.

I still would love to know how many pounds of force it takes to push the tip into the nose and how many pounds of force are created from the launch. From the moment of barrel exit the force is reducing.