quote:

Chris,..
say, what is the twist of your gibbs? or do I ahve the wrong chris?

My 6.5 Gibbs is 1-10".

Assuming I am the wrong Chris too.

Actually, my "Gibbs" almost makes me a "slow twister", don't it?

My Taylor is 1-12" though...so that probably makes up for it.

Cheers,
Canuck

Canuck,
heh, i meant chris sutton ...

but you raise an interesting point...

if 1x7 is fast enough for 4" long 223 bullets, and 1x10 is fast enough for 4" long 308 bullets, why do you NEED a 1x10 in a 510????

answer? You don't

quote:

Twist is only important to air stabilize the bullet and to let the bullet arrive at the target with a minimum or no yaw at all or angle of incidence.

This is correct and Harold Vaughn makes the point that, of the two precession cycles (fast and slow), the most persistent is the slow precession and this is dampened faster, the higher the SF is. (Rifle Accuracy Facts p182) This is of course applicable to hunting situations and not to long range shooting. Spin rate can also not control the angle of incidence between bullet and target. It does have an effect on the angle of attack of the bullet in flight.

Alf,
Shooting at a simulant square on will tend to minimise differences in SF. The bullet should impact the test medium at an angle if the differences are to be highlighted. We have done this with 145gr and 180gr FN bullets in 10" and 12" twist rates. We used a 4 mm polypropylene plate at a 20 degree angle placed directly in front of the stop box. In later testing on game, the 145gr FN was the clear winner from both twist rates.

quote:

The bullet should impact the test medium at an angle if the differences are to be highlighted. We have done this with 145gr and 180gr FN bullets in 10" and 12" twist rates. We used a 4 mm polypropylene plate at a 20 degree angle placed directly in front of the stop box

So, if RIP put the innertube "skin" on his Iron Buffalo at an angle, it would be more likely to show a difference in pentration than if it was perpendicular to the line of flight. Not a bad plan. RIP?

Canuck

Twist must be a very powerful aspect of a rifle.

This must be about the first thread on AR where the original poster/topic starter is converting a Weatherby rilfe and yet the Weatherby rifle was not ripped apart.

But back to the topic at hand.....as far as I am aware the twist required to achieve stability increases as the density of the media increases. So at 30,000 feet then perhaps a 100 grain 243 spitzer might be stable with a 1 in 12 twist but as we know that is not the case at sea level.

Mike

Mike375/8,

Long time no see.

Cheers,
Canuck

Canuck,

Saeed and Don had to reinstate me so as to bring the appropriate balance to the Political Forum

Mike

The scales were tipping to far to the left, huh?

Cheers,
Canuck

Hi Mike. Good luck in bringing balance in the Ignorance Crater. Much appreciated.

Canuck,
No tilted innertube skins for me and the Iron Buffalo. Maybe tilted gelatin surfaces covered with pig skin?

quote:

Maybe tilted gelatin surfaces covered with pig skin?

Sounds even better.

Canuck

RIP

Are you still having 375 Wby orgasms

As a side note, 85 grains of Varget (2208) and 270 Hornady Spire is shooting right on an inch from one of the 378s and 91 grains is doing the same with 225 Hornady Spire. Pressure is super mild and they are doing just under 2700 and 2900 respectively. Muzzle blast is very soft, softer than the H&H with full loads.

Results were also good with 2206. I don't think that powder is sold by Hodgdon but is about the same buirn rate as 3031 and is the canistered version of what our army uses in the 7.62

Mike

It is a shame none of you gentlemen ever got much of a benchrest exposure. Fifteen years ago noted benchrest competitor and barrelmaker Dan Lilja and some of his customers did some work on twist ratios for BR cartridges. They found the altitude a major player in projectile stabliization. A couple of the top Colorado shooters found that their slower twist 6PPC's shot poorly at a match in Seattle, and at the Super Shoot in Ohio. Both humidity rich and altitude poor compared to Colorado. One of his customers is/was involved in projectile development and testing at Picatinny Arsenal in NJ. He helped develop the algorythms that Sierra has that proved BC is variable, based on velocity range(s)...at least three separate BC's in fact. I believe some if not all of the data is available at his website. The conclusion at PA was that excessively fast twist was severely detrimental to projectile stability and accuracy. Wish I had copied all the data back then.

Rich

quote:

excessively fast twist was severely detrimental to projectile stability and accuracy.

But how much twist is "excessively fast"?

Cheers,
Canuck

But how much twist is "excessively fast"?

Canuck

It really comes down to the amount of accuracy you are looking for.

Fast twists in my experience are usually more fussy with loads, more likely to shoot different loads to different points.

One thing for sure and that is for all "real accuracy guns".....the slowest twist possible is the best. In fact I think this helps people get good accuracy from calibres such as the 6mms, 25s and 270s because a 1 in 10 twist is much slower in such calibres than a 10 twist in a larger calibre. Also seen with calibres such as the big 22s compared to 6mms. A 1 in 14 in 224 is like 1 in 15.2 in 6mm.

I have not done enough under good controlled conditions but in 300 Win bench guns using 10, 12, 13 and 14 twists....my feeling, as distinct from a definite conclusion, is that wind drift is greater with the faster twist.

As to penetration, I suspect 500 Grains is probably correct, because even though he is a pain in the arse I think he is a good tester and reliable reporter and at the same time I don't think he does testing in a manner to support a preconceived notion.

Mike

Ho hum. Some of those benchrest boys have to switch to faster twist if the temperature drops, or the barometric pressure increases.

Rich, you got that right. The Colorado shooters had to use faster twists when they came down to lower altitude and increased humidity.

Ain't life grand?

quote:

Originally posted by Idaho Sharpshooter:
A couple of the top Colorado shooters found that their slower twist 6PPC's shot poorly at a match in Seattle, and at the Super Shoot in Ohio. Both humidity rich and altitude poor compared to Colorado.
Rich

So the pro's had to go to faster twist with their 6mmPPC's just because of atmospheric conditions.

Canuck,
I will spread some mud on the pigskin too, and let it dry before I shoot.

Mike,
The .375 Weatherby is still the sexiest cartridge ever. Now I want one with 1:10" twist instead of those common 1:12" versions.

quote:

Originally posted by RIP:

quote:

Originally posted by Idaho Sharpshooter:
A couple of the top Colorado shooters found that their slower twist 6PPC's shot poorly at a match in Seattle, and at the Super Shoot in Ohio. Both humidity rich and altitude poor compared to Colorado.
Rich

So the pro's had to go to faster twist with their 6mmPPC's just because of atmospheric conditions.

Ron,
you KNOW damn good and well that smaller calibers require fast twist than larger calibers. and that a slow twist in colorado means that they didn't correct for STP.


Excessive twist?

GROSSLY - well, how about a twist faster than 50% of the greenhill formula required for stablization? so, if a 1x24 will barely make a .475 bullet work, a 1x12 would be the fastest...

more specifically - any twist more than 20% faster than the generally accepted twist for that caliber/ velocity...

examples

mythical - to establish BASELINE for a caliber: a 1x24 twist has a 15degree leading angle. 150% of that is 22.5 degrees, or 1x16.

practical - the 458 lott generally has a 14 twist. (winchester, remington, ruger, cz), or about a 25.71 deg lead... at 1.2X, anything faster than 11.67 twist should be considered over twist...

jeffe

jeffe

Sounds good.....but you still need to come back to 500 Grain's testing

Could you sell Dan a Breeding rifle with a slow twist???

Dan's testing has not been wood logs, iron maidens, buckets of butter etc.

Mike

As far as the 6PPC, they shoot from 62gr to as high as 70gr bullets, and you will not see a twist slower than 14.5" or faster than 13.5". A narrow range, and 14" is dominant. Cast Bullet Assn. match winning competitors are shooting the 30BR case, and run from 180gr to as much as 210gr bullets, and EVERYBODY (that wins) shoots 11" twist barrels. Velocity range on the 6PPC is 3200-3300fps, for the CBA guys 2100-2300fps. The universal manta is "...use just enough twist to stabilize..." when you get into the 1/4moa and smaller group expectations. Both groups have experimented with quicker twists, and both groups abandoned them for the 14" and 11" twist barrels very quickly. DGR bullets have a drastically different performance criteria...penetration; and expansion, or not.
Accuracy under 2 moa does not (IMHO) factor into the design process. Stopping power is the basic mantra here.

Premise:
The perfect softpoint should be found under the skin on the off side, expanded to twice it's original caliber, retaining 90+% of it's weight. Or, from the front or rear clear out the heart, lungs, and liver.

Premise:
The perfect solid should penetrate from shoulder to shoulder, should reach the shoulder after smashing the spine on a Texas Heart Shot, and on a frontal brain shot, reach the shoulder/spine area after passing thru the skull cavity.

I hope nobody disagrees with these two premise-es, or WE ARE IN TROUBLE here.

The problem; how to best accomplish that goal.

I leave that to the experts. I have, however, taken two buffalo with a Shiloh Sharps 45-70LRE using a 500gr lead bullet at 1470fps MV. One at 147 stepped-off paces, and one at 217. Both went down, and neither made it more than 30 feet, staggering punch-drunk to the mudwallow to give the death bellow.

Could it be that a properly shaped lead/tin/antimony alloy cast bullet in the optimum 2100-2250fps range would be all we need in a 40+ caliber rifle? Heresy, perhaps, but is it worth testing along side jacketed?

Rich

Mike378,

I think all of Dan's DG rifles have the slow (traditional) twist.

Rich

quote:

Originally posted by ErikD:

quote:

Originally posted by jeffeosso:

quote:

Originally posted by ErikD:
Have any of you guys who are whining about 500grains not replying yet,:

Odd way to provide information.. please see post above, he has repeatedly refused to answer these questions.

perhaps "whining" is a bit strong, .. how about requesting information that is pertinent to the discussion, yet refused to be provided?

Provide information??? I was merely pointing out what it looks like some people are doing. Although this might not be their intention.

Erik,
he's been back a couple days and still not answered what fast twist rifles he has... though he has those that ask on ignore, as of now.

perhaps you could ask dan the same question.... what rifles he has in .400 or larger with at least a 1x10 twist or faster, as he preaches...

then again, most snakeoil salesmen didn't drink the koolaide, either


jeffe

quote:

Originally posted by 500grains:
Please point to the post that says I have a .500 A2 with any twist whatsoever.

But perhaps Santa snuck one into my safe...

well, it certainly is put up or shut up time..


i am dropping a check in the mail in the next 30 minutes for a 1x10 twist .510 barrel.

it will be chambered for 510wells, as i have that reamer, and loaded against a former machine gun barrel 510 wells.

we will see the effects of twist on pressure, velocity, and penetration on an mdf target, and perhaps, if the good lord is willing, on the bullet test tube as well.

should anyone wish to include bal. gel, i invite them to have it shipped to texas.

should you feel that shooting mdf/plywood is a flawed test, well, let's see you fast twist rifles, and your test results...

otherwise, it's just blowing hot air up my kilt

jeffe

[

quote:

Originally posted by Idaho Sharpshooter:
A couple of the top Colorado shooters found that their slower twist 6PPC's shot poorly at a match in Seattle, and at the Super Shoot in Ohio. Both humidity rich and altitude poor compared to Colorado.
Rich

That's a bunch of hooy! I was at that match and it is always the case with out of state shooters that don't do well. I didn't finish first but was the first loser and my rifles have a 14 twist barrel.

REMINDER: I do not engage in discussions with dishonest people.

quote:

Ignored post by Idaho Sharpshooter posted 26 November 2006 10:51

Ignored post by Idaho Sharpshooter posted 26 November 2006 10:52

Ignored post by jeffeosso posted 30 November 2006 09:39

Ignored post by jeffeosso posted 30 November 2006 09:44

quote:

Originally posted by jeffeosso:

quote:

Originally posted by ErikD:

quote:

Originally posted by jeffeosso:

quote:

Originally posted by ErikD:
Have any of you guys who are whining about 500grains not replying yet,:

Odd way to provide information.. please see post above, he has repeatedly refused to answer these questions.

perhaps "whining" is a bit strong, .. how about requesting information that is pertinent to the discussion, yet refused to be provided?

Provide information??? I was merely pointing out what it looks like some people are doing. Although this might not be their intention.

Erik,
he's been back a couple days and still not answered what fast twist rifles he has... though he has those that ask on ignore, as of now.

perhaps you could ask dan the same question.... what rifles he has in .400 or larger with at least a 1x10 twist or faster, as he preaches...

then again, most snakeoil salesmen didn't drink the koolaide, either


jeffe

And you are pointing this out to me because???

I must admit that I am one of the people here who find these various twist threads to have become exceptionally boring! As does most likely the majority of AR members!

Hey PegLeg,

what year did you see the disaster at Kelblys? I think it was 1992, the year I went to the Super Shoot with Russ Hayden. Skip Otto embarrassed the heck out of me when I made the mistake of telling him I wasn't going to shoot because I had not budgeted the $$$. He went around the shooters meeting in the big barn with his hat out and asked for 1$ donations to fund my entry fees. Then I say, oops don't own a BR rifle, all I shoot is rockchucks...so Alan Hall offers to let me shoot his rifle...I ended up 89th out of 387 shooters. Dave Brennan told me I could not finish last unless I crossfired at least twice...because several people would do so once!
Ambler and the "firewalker" boys were hot with the 14.5 twist up there and at Helena for Lilja's match, but the low altitude and high humidity just killed them.

Rich

quote:

Originally posted by jeffeosso:

quote:

Originally posted by 500grains:
Please point to the post that says I have a .500 A2 with any twist whatsoever.

But perhaps Santa snuck one into my safe...

well, it certainly is put up or shut up time..


i am dropping a check in the mail in the next 30 minutes for a 1x10 twist .510 barrel.

it will be chambered for 510wells, as i have that reamer, and loaded against a former machine gun barrel 510 wells.

we will see the effects of twist on pressure, velocity, and penetration on an mdf target, and perhaps, if the good lord is willing, on the bullet test tube as well.

should anyone wish to include bal. gel, i invite them to have it shipped to texas.

should you feel that shooting mdf/plywood is a flawed test, well, let's see you fast twist rifles, and your test results...

otherwise, it's just blowing hot air up my kilt

jeffe

jeffe...when you get tired of thet barrel let me know

boom, you'll have too much fun with it! There'll be no hope or chance of you making a recovery! Then el jeffe has to be your sponsor and so on.