Nearly everyone complains that Remington and Kimber were smoking krak (sp?) when they chose a 9" twist for their 260s. (I believe Remington introduced the 140 grain load in 1997 along with the 260). This same issue unfolded in 1994 when they ran the 9" twist 6.5x55 in the Classic and likewise started producing a 140 gr. factory load. Similarly, with the Whelen in 1987-88 with the 16" twist and the 200 and 250 grain factory loads.

But why would Remington choose a twist that would undermine the accuracy reputation of their own rifles and their own factory ammo? Perhaps they are profoundly stupid, but there must have been some accuracy testing, etc. before making the twist call. Especially Remington, which has a long history of producing fairly accurate factory rifles (relatively speaking).

Next, if faster twists were always better, then why would any profit-maximizing company do otherwise? Is it more expensive to produce faster twist barrels? Are there difficulties with over rotation - does it accentuate bullet imperfections and therefore hurt accuracy? Does it hurt velocity? Cause extra fouling?

Finally, if I have a 9" twist 6.5mm barrel that shoots 140s into 0.5 MOA, can I presume that the bullet is stabilizing properly?If so, can anyone else shooting the same same bullet at the same velocity (using a 9" twist) blame poor accuracy on stability issues?

(I realize bullet shape and length matter, but I already have too much in this post...)

possibly, with so many big companies being run by the accountant's pencil these days, remington is following suite and whoever is driving the pencil knows it's cheaper to let someone else make barrels for them. the down side is that they (the drivers) couldn't give a rams anus about wheather the barrel is the right twist for the bullets that are readily available..."just get the thing on the racks, Al, it'll sell with our name on it". " who cares if the twist ain't right, someone else will come up with a bullet if we get the gun out there".

the 1:9" twist is entirely adequate for any 140gr bullets.

where the 1:9" twist doesn't work is for 160gr bullets which are NOT needed in the 260Rem.
Unless you are some kind of cheap bastard that'd rather complain about not being able to shoot cheap "Cup & Core" 160gr bullets

Hey, if a 140 exits any animal you plunk them into what is a 160 supposed to do differently?

Remington isn't quite as stupid as some of the people whining about not being able to shoot 160gr bullets out of the 260rem woud have you believe

But if it had the faster twist so that 160's could be used those same people would certainly be whining about the longer bullet intruding on
propellant space.

to quote Jesus via Monty Python;
"there's just no pleasing some people".

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quote:

Originally posted by Allan DeGroot:
Unless you are some kind of cheap bastard that'd rather complain about not being able to shoot cheap "Cup & Core" 160gr bulletsAD

Cold day in PA, Allan??? roger

all of my 6.5 bullets are 129 grain and smaller so can someone that has both 140s and 160s please tell us the difference in actual measured lengths?....since the 160 is a round nose, I'm suspecting there is very little difference.

Since I've never heard anyone complain about lack of stabilization of the 160 partition in the 1-10" twists .270 rifles I have a sneaking feeling the 160 in the 6.5 rifles will stabilize just fine as well in a 1-9" twist.....

without actually having both in front of me i can't say, specificly, but a round noser will have it's c/g farther forward and i would think that would actually fool the bullet length/ twist relationship into acting like the bullet is longer than it is, possibly needing more twist.....(?)......that said, i would also think 9 inches would stabilize, at the same time they don't in my 6.5x.270 (9 inch w/.710" muzzle, in other words, "not too whippy"), they don't group as well as 129's and 140's do, so maybe there's something to this.... the combination of a more forward c/g (round nose 160) and more (for what it's worth) rifling contact????...i dunno... maybe it's just alot of bullet weight for that caliber.

FWIW the center of gravity is not a factor in the greenhill formula for twist rate....only the length and diameter of the bullet and the speed of the bullet.

Try it here

Hornady 160 RN- 1.242"
Hornady 140 SP- 1.250"

According to greenhill it would take a 1;8.4, and at 2800+ a 1;10" twist, both stabilize in 264 win and 6.5-06 9" twist. I've never measured my winchester but think it is a 1 in 8?

now i'm no phyisicist, and i'm no bonafide edumacatered gun guru-smith, but i spent a lifetime slingin' skinny sticks through the air competatively and i gaurantee you that given two projectiles of equal length and weight but with different longitudinal c/g's, will stabilize differently and will have each, thier own rotational "sweet-spot" where a specific rate of twist(or spin) will act upon the polar moments through the c/g during flight to keep the front of the projectile ahead of the rear of the projectile and in rotational alignment with the arc of trajectory. the fact that you must enter the length of the bullet and it's weight tells the program where to plot the lcg. if it didn't take the lcg into consideration, rate of twist would mean absolutely nothing to stabilization.
them skinny sticks may only be going 300 fps., but the rules ofphysics and dynamics apply the same way.

sorry about that... i can't type today.

I was always under the impression that a bullet that was overspun would have its center of gravity follow the trajectory, but the long axis of the bullet would follow the angle of departure, kinda nose up if you will. At extremely long range this would cause the side of the bullet to be exposed to more wind resistance, slowing the bullet down fast, and eventually become unstable.

9.3x62, I think you have hit some of the modern anomolies of the greenhill formula. Greenhill was never designed for anything but lead, so we transfer "weight" for specific gravity with no regard whatsoever for material construction. For example, solid copper does NOT fit Greenhill since the specific gravity of copper is much less than lead. The other thing that has never been completely reconciled is that Greenhill never envisioned a bullet length more than 3 times caliber since nothing being fired at that time (1870s) in the artillery world was longer.

So, Greenhill is just an estimation calculator, not anything close to gospel. It is a good place to start and find out what happens in the real world.

I am not a mathematician, but I spent a lot of time with them at Bell Labs where some of this stuff was discussed. Just my opinion.

swheeler...
yup, it's got to do with the relationship between the location of the lcg, the the distance the polar moments are away from it. there's lots of particulars, but essentially, the longer the " dynamic couple" between lcg and rate of spin, the greater the gyroscopic effect. the greater the gyroscopic effect, the more the projectile wants to stay in the attitude it started off in. so a long heavy bullet spun too fast will leave the barrel in a nose up attitude because of the trajectory needed to get it to the target. it will have a long dynamic couple (distance between lcg and polars) and a too high coeffient of gyro effect, so it will want to stay nose high because it's lcg is not centered in it's length. but, it will need to be spun fast because it's long and as long as it does the same thing every time it will go to the same point of impact, barring outside disturbances.
another bullet, same length, but different dynamic couple because of weight and/ length will travel in a different attitude and land in a different location because of the time it takes during flight to get settled into the path of trjectory.

Pretty simple/basic concept to understand. The old a 140 is a 140 bullet concept just doesn't work, but danged hard to get through to some.

First, the rem 700 classic in 6.5x55 has a 1-8" twist rate, i know because i have been shooting one for about 10 years. There really isnt that big of a difference between a 1-8" and 1-9" rate. My swede is in a long action, while the .260 is in short actions so you wouldnt be shooting 160's in a .260 with that short magazine.

If you had a .260 built for long range shooting, with very long 140gr bullets like a VLD or A-max then the 1-8" would be the only way to go.

The 35 Whelen is a curiousity, all .358wins have 1-12" rates so why the 1-16" rate for the Whelens? They will certainly stabilize 250gr bullets but for how long is the question, will they be tight at 250 or 300yds its max range? My Whelen has a 1-14" and it shoots great but i wouldnt hesitate to go with a 1-12" rate as its harder to over stabilize a bullet today because they are so concentric.

quote:

Originally posted by DarkStar:
First, the rem 700 classic in 6.5x55 has a 1-8" twist rate, i know because i have been shooting one for about 10 years.

I have been shooting one for 15 years (bought one new in 1994). There was a heated debate here some years ago between 8" and 9", and the consensus was that it was a 9". I called remington about even, and they told me 9", but even they aren't always the best source of info... so who knows. I tried the cleaning rod test trick, and that seemed to support 9" more than 8", but again, not an exact science.

Anyway, welcome to AR. Also, what type of accuracy do you get out of your classic? Any trouble with ejection - does it like to leave empties in the raceway ever?

i think you'll find that when whelen desinged and the .35, he had elk at medium ranges in mind, that might explain the slower twist. only when it was found to be such a devestating killer at those distances that people started pushing the range and the thought that a tighter twist might help out at longer distances

quote:

... if a 140 exits any animal you plunk them into what is a 160 supposed to do differently?

For what it is worth, I would like to know the answer to that one! Better penetration for bad angles perhaps? More bullet to do the job after hitting heavy bone?

quote:

Unless you are some kind of cheap bastard that'd rather complain about not being able to shoot cheap "Cup & Core" 160gr bullets

OK, I am guilty! Actually, I find it rather fun getting results from the 'cup 'n core' bullets to which end I like to use heavy bullets at lower velocity. I am even going retro to very heavy cast bullets with a deep hollow point for 1800fps or less performance. It's fun and theoretically allows me to shoot more on my budget. And with varminting, I get about as much satisfaction from a single kill as I might otherwise get from multiple kills with store-bought bullets! This counts for a lot when varmint numbers are declining!

The round nose bullets will allow a heavier bullet to stabilize in a given barrel. Two things are different, ta RN bullet of the same length as it's spitzer counterpart will have more of the mass is nearer the OD plus nearer the nose. This makes for more stability.

Does anyone know the spin that is required to 'overstabilize' a bullet to the point where it will maintain the barrel attitude all the way down range? (Ignoring bullet structural failure due to gyroscopic forces).

there's an interesting article in Gun Digest, 1976, comparing 1:9 and 1:10 twist barrels with the 6.5 swed. Bullet shape was NOT taken into consideration. long range shooting was the desired goal.

The 1:9 loved 140 centrix.

The 1:10 barrel loved Sierra 85hp and 140 bt.

Thanks for the welcome, my classic has never had a problem with feeding,ejection or brass and its very accurate. It shoots from around 3/4" to 1-1/4" groups and has done everything and more that i have ever asked of it.

Getting back to the 35 whelen, i believe that because remingtons own factory loads are anywhere from 150 to 250fps slow that the 1-16" rate works well. Who would shoot a 250gr bullet @2,400fps past 250yds? Once you start shooting anything over 250grs like the 270gr North Fork, 275gr Hawk, 280gr a-frame or 300 gr Hawk and 310gr Woodleigh you would definately benefit from a 1-14" to 1-12" rate.

Why would Remington do this? Why would they re-release a 673 or 600,660 replica? Why would they invent the SAUM and then let Winchester push em right out of the market. Those SAUM's would be great in the Alaskan Ti but atlast they are not chambered in em, very curious indeed. Marketing guru's and bean counters very often has a lot of sway with a company.

Just checked my twist rate on the classic and its coming up as 1-8" but i could be off although i dont think so.