250-3000

SwampFox · Posted: Sat Mar 07, 2009 7:11 am Post subject: Re: 250-3000

I will bet you a crisp $100 bill that the Hornady which is at least 1.016 in length and 145% of the proper length will not stabalize in a 14 twist, at any velocity. Explain how the bullet spins faster than the orgin of the revolutions, the rifling twist rate.
Best,
Ed

chambered221 · Posted: Sat Mar 07, 2009 8:43 am Post subject: Re: 250-3000

laurent,
The info I have list the current Hornady 100 gr. Bullet ( SP 2540) at 0.987
That differs with the info swampfox has. You might want to look at this a little closer before spending your money. It’s possible they made more than one 100gr. bullet.

swampfox,
I definitely would not bet on this one, I’ve already acknowledged we are working one the edge with this one !!!

Here’s my explanation on twist, hope I wrote it in a manner that is understood.
The bullet will not spin any faster than the twist gives it, I agree with you on that.
However if you double your velocity, you also double how many times the bullet makes a revolution over the same distance.
Look at it this way, the time (in seconds) it takes to travel a given distance.
The bullet is still making one turn every 14 inches, just doing it a lot quicker giving it a faster spin rate not a faster twist rate.

SingleShotLover · Posted: Sat Mar 07, 2009 11:57 pm Post subject: Re: 250-3000

221...That's as good an explanation as any I've ever been able to come up with. You are right that the difference is in the amount of time necessary to make the same number of revolutions is the determining factor. I have struggled many times to explain that difference.

A 1 in 14 inch twist results in 257 (and a bunch of decimal places) complete rotations at 100 yards and will remain a constant regardless of speed. This amounts to a time-of-flight of .132 seconds at 2,500 fps. Increasing that velocity to 3,000 fps give a time-of-flight of around .109 seconds. This decreases even more as speeds increase. The number of rotations stay the same over the distance, but those rotations are compressed into a shorter time-frame which, as you noted, increases the speed of the spin...not the number of revolutions. This also helps explain why certain thin-jacketed bullets shoot fine at 3,200 fps but self-destruct when boosted to 3,600 fps from the same barrel.

The twist rate induces a constant revolution rate, but the velocity controls how fast that bullet has to spin in order to make those revolutions in that distance. This is roughly comparable (though in a different dimension) to a 15" tire at 10 mph and 60 mph. Over any given distance the tire will rotate the same number of times, but at 60 mph it will have to do so far faster than at 10.

chambered221 · Posted: Sun Mar 08, 2009 8:58 am Post subject: Re: 250-3000

Laurent, A few things to keep in mind should you get the 100gr. bullets working !!!

Just because you get them to stabilize at 100 yards don’t mean they will be stable at a longer distance.
Do some proof testing at the longest realistic distance you might take game at.
Also do it in the type of weather you’ll more than likely encounter. A drop in temperature could change your results.

Pumpkinslinger · Posted: Sun Mar 08, 2009 12:29 pm Post subject: Re: 250-3000

Just to throw my two cents in again...

The bullet's stability is dependent on the speed of revolution, i.e. revolutions per minute, not on the distance of revolution, i.e. inches per turn. You can fire the same bullet in the same gun at increasing velocities and go from keyholing to decent groups. I once worked up some loads for a friend's .22-250 using the Speer 70 grain bullet. At the "start" load the bullet was keyholing at 100 yards. As we stepped up the loads, increasing the velocity and therefore the RPM, the bullet settled down. This incident occured fairly early in my reloading experience and sure was enlightening!

harrys · Rookie Member Joined: Jan 19, 2009 Posts: 16

I found imr 3031 to work well for me in my 99 with nosler ballistic tips using 33.0 grs. But if u want a real shooter in it try some 75 vmax's with some imr4320with 35.0 grs ,,,, i'm getting low .2's .100's i only get .668.

harrys · Rookie Member Joined: Jan 19, 2009 Posts: 16

I have a savage 99 and they are intended to shoot best with bullets in the 75 ,85,87, ger wieghts and kept close to 3000 fps with cases close to full . Mine spits 75 vmaxes with 35.0 grs imr 4320 into .161 wwhich blows me away i have 2000.00 rifles that don't shoot any better. I spend alot of time tailoring loads for all my rifles also.

laurent · Member Joined: Sep 07, 2006 Posts: 65 Location: Quebec

I have not decided yet if I will go with the 100grs bullets in that caliber.
What I find strange is that Hornady use the same gun as mine a Savage model 99 1-14 twist for their testing and nowhere in the manual are they mentioning having issues with the 100grs,only with the 117grs.
Same thing with Sierra using a Mauser with 1-14 twist.