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Boring- You know I enjoy a spirited debate. Especially with people who are open minded and ACTUALLY KNOW WHAT THEY ARE TALKING ABOUT! However, i'm not really interested in doing so with people with make believe and irrevelant experience. My challenge stands! What no takers? This thread is a waste of my time.-Rob


Never underestimate the power of stupid people in large numbers to do incredibly stupid things- AH (1941)- Harry Reid (aka Smeagle) 2012
Nothing Up my sleeves but never without a plan and never ever without a surprise!
 
Posts: 6314 | Location: Las Vegas,NV | Registered: 10 January 2001Reply With Quote
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Rob,

I was at McMillan Brothers in Phoenix a few months ago attending a sniper class and their barrel maker was explaining barrel options to the class of mostly active military marksmen. (A freind of mine was teaching the class).

They use a 1-10 in all 338's regardless of case capacity. It just wont shoot with anything else according to them, either quicker or slower.

They use two very very quick twists (I think 1-7 and 1-8) in the blown out 6mm x 257 case, thd 6mm XC. They were raving about it for 1,000 yd shooting. (McMillan makes the space age Tubb 2000 bolt action w 10 round magazine rifle).

Their variouis 6.5 mm's also use very quick twist, including the fast 6.5 x 284.

McBro's build as many 50 calibers as anyone, including all of those used by Canadadian and British armed forces. They also make the .338 Lapua for Britan which is replacing their 7.62mm and 50 calibers.

So there certainly are bullets and ctgs which need very quick twist even for paper punching.

I would not assume all big bores act like a 50 BMG. My 450 Dakota certainly benefitted from a 1-12 twist, and my 460 GA from a 1-10.

Runout was probably not the reason the Hornady FMJ's exited the La Grange stop box sideways at just 21-36 boards instead of staying point forward in quicker twist rifles. This only happened in the 1-14 twist. I suppose it is possible that the 450 Ackley got all the bullets with lousy run out and the 1-12 and 1-10 twist barrels got all the good bullets, but it is unlikely given the large number of test shots.

I also tested various military calibers in the La Grange stop box.

55 grtain M193 ammo will penetrate 11 boards in the stop box when fired from a 1-12 twist and 13 boards when fired from a 1-7. It still breaks in two at the cannelure due to very high rotatinal velocity and use of a 16/1000 thick jacket with weakened canelure. But here again, you have increased penetration w quicker twist, even with an unstable military bullet.

Andy
 
Posts: 1278 | Location: Oregon | Registered: 16 January 2004Reply With Quote
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quote:
Runout was probably not the reason the Hornady FMJ's exited the La Grange stop box sideways at just 21-36 boards instead of staying point forward in quicker twist rifles.


In the interest of ruling out any other possible explanations for one bullet penetrating any further than the other, is it possible that some of the boards in the test were not exactly parallel to each other or perpendicular to the bullets path. If I look at the pic that was posted some of the boards look like they are slightly off cant or at different angles. Is it possible that a bullet hitting a board at a different angle might cause it to "fishtail" or "tumble". I have read about "angle of incidence" being a factor in a bullets flight and that might be one alternative explanation.

I think any scientist will tell you that it isn't an empirically sound or valid experiment if you have variables present. I am not saying your results don't prove anything but with the variables present you can't really say that it is a valid experiment.
 
Posts: 436 | Location: Houston, Texas | Registered: 27 December 2005Reply With Quote
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Jeff,

Please stop intentionally misinterpreting my posts in your childish charade that attempts to attribute to me a position that is 180 degrees opposite of what I said.

If it helps you, note that it was some guy 100 years ago who decided to use a 1:20 twist for the 470 NE, not me. But you already know that.

So keep playing your childish game, as I know you will do. Instead of building more ridiculous wildcats, you should spend some money using those guns to hunt large animals. With a bit of field experience under your belt, your views might change.
 
Posts: 18352 | Location: Salt Lake City, Utah USA | Registered: 20 April 2002Reply With Quote
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JMJ888,

Some of the solids and FMJ's tested:



I think you need to look at the macro picture.

The only bullets to be unstable had 1-14 twist.

The only bullets in .375 to be unstable had 1-14 or 1-12 twist. (The heavier 458's were less likely to destabilize than the lighter .375's but that's another story).

The photo of the stop-box was taken after a bullet test. I re-aligned them with a rubber mallat after each shot.

None of the boards were perfectly perpendicular, but all bullets tested had to over come this same lack of perfect alignment, and only the 1-14 twist .458's could not handle it.

Bones in animals are not perfectly aligned either!

A hunting bullet should be able to handle small or even large variations in angle of attack.



A 1-14 twist .458 may be stable in air but it sure is not in a La Grange stop box. Pictured one of just three 1-14's that kept point forward, and even this one is tipped downward about 30 degrees.

Use at your own risk.

And when you test a couple hundred bullets in five different calibers and five different rates of twist be sure to let me know!

Andy
 
Posts: 1278 | Location: Oregon | Registered: 16 January 2004Reply With Quote
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quote:
Originally posted by 500grains:
Jeff,

Please stop intentionally misinterpreting my posts in your childish charade that attempts to attribute to me a position that is 180 degrees opposite of what I said.

If it helps you, note that it was some guy 100 years ago who decided to use a 1:20 twist for the 470 NE, not me. But you already know that


quote:
Originally posted by 500grains:
I have not performed penetration tests with the 470 NE. Keep in mind that with the old 1:20 twist the 470 NE had only an ok reputation. It is only lately, with Federal making ammo, that the 470 NE became king of the hill.


Dan,
it is impossible to READ your post and ascertain that you meant POPULARITY in your statement. I read what you wrote, in the context it was written, not what you wish to revise later.

It seems to be a standing problem, on all internet forums, of persons reading INTO other's statements. I simply took your DIRECT statement at face value.


So, here's a little bitty simple question.

If you had a 470 NE rebarreled to 1x10 barrels, and put FACTORY Federal 470 NE rounds, would you exceed that rounds pressure specification?

The answer, of course, is yes, by your own statements.

I'll stick closer to the 100 years of proven service than a realitivly recent concept of super twist... Thanks, but no.

Jeffe


#dumptrump

opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com
 
Posts: 38374 | Location: Conroe, TX | Registered: 01 June 2002Reply With Quote
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Andy,
Here's a pic from www.470mbogo.com on bullet stabilization. results are slightly different than yours. Though this picture shows the effect of DISTANCE on "bullets going to sleep" it shows an interesting result

and RIPs tests, if i recall correctly, showed FP bullets certainly didn't YAW as much.

But, anyway, all the shots from this picture are from the same gun, with FP bullets... speed adjusted for difference.



I might recall incorrectly, but I believe this gun to have a 1x18 tist, though it may be a 1x16

Interestingly enough, the rifle with a 1x14 twist had the deepest penetration in wood (which I'll be soon told isn't the same as an animal)... AS the rifle in question was a rechambered CZ..
http://www.470mbogo.com/BigBores/BigBores7.html

with the second being a 1x18 twist...

and a 500 A2, with a 1x10 ?, twist, came in a distant third (and in the pack with the rest), though the velocity was the same with the first and third... the FIRST place was a slower twist... bewildered


Seems that twist has alot to do in one scenerio, and little in another...

But, without a doubt, twist adds to the pressure of the load...

jeffe


#dumptrump

opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com
 
Posts: 38374 | Location: Conroe, TX | Registered: 01 June 2002Reply With Quote
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Jeffe,

You asked Dan:

"If you had a 470 NE rebarreled to 1x10 barrels, and put FACTORY Federal 470 NE rounds, would you exceed that rounds pressure specification?

"The answer, of course, is yes, by your own statements."

How come I can shoot a 55 grain M193 5.56mm in my 1-12 twist M-16A1 and also in my 1-7 twist M-16A4?

Thousands of ronds every year.

Andy
 
Posts: 1278 | Location: Oregon | Registered: 16 January 2004Reply With Quote
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Andy,
The question on the 223 would be.. which rifle produces higher pressure, all else being equal... the 1x7, of course. But, and here's a funny, if you loaded that round with a "stupid" fast powder, and reached X PSI, would the bullet go as fast as a regular load? Answer, NOPE... as "pressure" that makes a bullet go faster is the area under the pressure curve, not the peak pressure.

jeffe


#dumptrump

opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com
 
Posts: 38374 | Location: Conroe, TX | Registered: 01 June 2002Reply With Quote
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Jeffe,

I am not surprised that your 470 Mbogo out penetrates a fifty caliber regardless of twist.



My favorite 0.50 caliber.

1,000 shots per minute right trigger, 2,000 spm left.

And it has a 1-30 inch twist! (For use with 347 grain APDS at 4,100 fps).

PS The 1-7 inch twist M-16A2 has a few fps higher velocity than a 1-12 when shooting M193. The point is, it is just not a significant or dangerous situation. So why worry about it?

Andy
 
Posts: 1278 | Location: Oregon | Registered: 16 January 2004Reply With Quote
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Andy,
Keith's got a video shoot of a QUAD minigun setup!!! talk about amazing... the brass POURING off it looks like someone was dumping from the a concret truck... a STREAM of them.

It's Dave's penetration tests... I really believe, of all the wildcats in and around AR, his is the BEST for a magnum sized action, and might be the best there is!!

The 458 Ackley, though, went just a hair deeper.

jeffe


#dumptrump

opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com
 
Posts: 38374 | Location: Conroe, TX | Registered: 01 June 2002Reply With Quote
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Jeffeoso i have very low price buffalos ,in january send me a pm if you are intersted.Juan


www.huntinginargentina.com.ar FULL PROFESSIONAL MEMBER OF IPHA INTERNATIONAL PROFESSIONAL HUNTERS ASOCIATION .
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Posts: 6362 | Location: Cordoba argentina | Registered: 26 July 2004Reply With Quote
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quote:
Originally posted by jeffeosso:


If you had a 470 NE rebarreled to 1x10 barrels, and put FACTORY Federal 470 NE rounds, would you exceed that rounds pressure specification?

The answer, of course, is yes, by your own statements.


Once again I never said that. So please STOP lying about what I said. In fact I would not expect anything of the sort.

Perhaps you should consult Don G. who posted on the African Big Game Hunting forum about losing 5 fps (2400 fps down to 2395 fps) as a result of switching a .416 to a fast twist barrel.
 
Posts: 18352 | Location: Salt Lake City, Utah USA | Registered: 20 April 2002Reply With Quote
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quote:
Originally posted by 500grains:
quote:
Originally posted by jeffeosso:


If you had a 470 NE rebarreled to 1x10 barrels, and put FACTORY Federal 470 NE rounds, would you exceed that rounds pressure specification?

The answer, of course, is yes, by your own statements.


Once again I never said that. So please STOP lying about what I said. In fact I would not expect anything of the sort.

Perhaps you should consult Don G. who posted on the African Big Game Hunting forum about losing 5 fps (2400 fps down to 2395 fps) as a result of switching a .416 to a fast twist barrel.


Dan,
you said
quote:
Originally posted by 500grains:
If the rounds are loaded so hot that a change in twist to 1:10 makes them dangerous, then the problem is in the loads, not the twist.


I d on't have a CLUE what else you could have meant by this statement, other than pressure would go up with twist

Then again, PEAK pressure has zero to do with velocity... if it did, then could load BMG cases with bullseye and get the same speeds.

Now, If you don't like your own quotes, perhaps you might contempt on the vagarities of "lying"

jeffe


#dumptrump

opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com
 
Posts: 38374 | Location: Conroe, TX | Registered: 01 June 2002Reply With Quote
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quote:
Originally posted by juanpozzi:
Jeffeoso i have very low price buffalos ,in january send me a pm if you are intersted.Juan


Juan,
good to hear from you. PM sent

jeffe


#dumptrump

opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com
 
Posts: 38374 | Location: Conroe, TX | Registered: 01 June 2002Reply With Quote
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quote:
None of the boards were perfectly perpendicular, but all bullets tested had to over come this same lack of perfect alignment, and only the 1-14 twist .458's could not handle it.


Out of curiosity what speed where all of the bullets traveling when measured from the chronograph?
 
Posts: 436 | Location: Houston, Texas | Registered: 27 December 2005Reply With Quote
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Get a clue Jeff. If your loads are too hot as a result of a change of twist, then your loads are TOO HOT. Safe loads will not give you any trouble regardless of the twist.

Once again, it is time for you to stop intentionally misunderstanding my posts and then misquoting/lying. If you insist on falsely attributing to me things that I did not say, then it would be better if you did not respond to my posts at all.
 
Posts: 18352 | Location: Salt Lake City, Utah USA | Registered: 20 April 2002Reply With Quote
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JMJ888,

There were 37 different shot-strings, so you will have to wait for the article to compare it to your own exhaustive research.

Distance was 30 yards, as according to the late George Hoffman, "That is the distance a charge is likely to develop."

(I shot my elephant at 9 paces, but what do I know? At this range stability is even more important!)

The 458's with 500 grain Hornady steel Jacketd FMJ-RN were going from 2,021 fps in std BRNO 602 with 1-14 twist (25 inch barrel) to 2,401 fps with 450 Ackley with same twist.

Even at 2,400 fps a 1-14 twist will not stabilize a conventional 500 grain FMJ RN.

2,397 fps for 450 Dakota with 1-12 inch twist. Fastest 1-10 was 2,367 fps. (Different days, rifles, and temperatures).

Downloaded 1-12 and 1-10 twist to .458 Winchester velocites were 2,030 - 2,050 fps. Between 1 and 29 fps of shots from 458 winchester and BRNO 602.

These velocites are not exactly the same so it probably completely invalidates the test.

Hope you can do better next time.

I was not trying to conduct a scientific evaluation by the way, just get ready for an elephant hunt.



Glad I did too!

PS, note the slightly larger than diameter entry hole from the North Fork Flat Nose, and sub-diameter TCCI-RN below it.

Andy
 
Posts: 1278 | Location: Oregon | Registered: 16 January 2004Reply With Quote
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Hi Andy,
I'm wondering if some of your results are do to bullet nose shape more than bullet stabilization. I had problems keeping the Hornady500 grain .458 round nose solids in the test box with wet newspaper. They would build up material on the front of the bullet as they drove through and it would invariably change the direction of the bullet. Some completely left the test bow within 20 inches. They would drive straight in plywood though. I would think that in animal tissue which would be a compromise between plywood and wet newspaper that the bullet veering off course could be quite common. On Canucks recent trip to Africa he tested a 500 grain Bridger bullet shot from his 470 Mbogo that has a 1:14 twist rate. The shot was straight on from the front aimed through. The bullet entered and broke up 12 inches of heavy spine and was recovered in the last two inches of the hind quarter. Almost a complete length wise penetration on a Cape Buffalo. I experienced the same sort of penetration on Cape Buffalo with a 500 grain Swift A-Frame on my trip without the bulet going through the 12 inches of spine. That bullet was mushroomed out to .875 when recovered.I would think that you might find your results to be different with a change in bullet selection. Thanks for posting your results. I know how much time and effort it take to do the testing.
Take good care,
Dave
 
Posts: 1247 | Location: Sechelt B.C. | Registered: 22 May 2002Reply With Quote
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PRESSURE AND VEOCITY CHANGES WHEN SWITCHING BETWEEN 14" AND 7.5" TWIST RATE ARE LESS THAN 1%. Acording to some studies.

Don G's calculations involved a 400 grain .416 in a 14" twist versus a 10" twist. Rotational kinetic energy for the two bullets, both at 2400 fps, were about 22 ft.lbs.(14" twist) versus 44 ft.lbs. (10" twist), IIRC. He then assumed this KE would be siphoned off from the linear KE of the bullet, making a difference of less than 1% KE drop, and way less in velocity for the faster twist. Negligible. But the faster twist will do better with any of the longer monometals, or any bullet you want, regarding stability and therefore accuracy and penetration, for DG application.

This may be true. thumb

1:9" twist Pac-Nor, or 1:10" twist McGowen would be my readily available choices for a 500 A2.

In the Iron Buffalo, a 10" twist 470 Capstick 500-grain North Fork FP at 2350 fps penetrated the same as a 470 Mbogo 16" twist at 2550 fps, though the 470 Mbogo made a bigger mess of wood and water splash.

I could not keep round nose brass solids or FMJ round nose solids in the iron buffalo. They exited the sides before half the penetrtion of the FN's, whatever the caliber weight or velocity, including with the 10" twist Capstick at over 2350 fps. Bullet nose shape is definitely of utmost importance for solids.

The 10" twist 500 A2 with a GSC FN at about 2450 fps MV will go through 8 feet of bison and exit reliably on southside shots at northbound bulls, stopping them in mid stride.

 
Posts: 28032 | Location: KY | Registered: 09 December 2001Reply With Quote
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Dave,

Thanks for the note.

You, Dan, RIP, Norbert, Gerard, and I are the only ones who seem to be getting their hands dirty. (Or should I say wet?)

All the data I just quoted was with the same bullet, an old style (steel jacket) Hornady FMJ-RN.

So they all had the same chance to do well, or not.

The problem with wet newspaper occurs when it is not so wet. That is when you get the build up of hard dry paper that really decelerates a bullet!

IWBA has developed a protocol for using wet pack but I dont think anyone uses it, it is so complex.

It is very hard to acheive consistant results w wet pack, but it is possible w IWBA methodology. It's just easier to make up a huge batch of Kind and Knox gelatin than get wet pack right!

That is probably why you and I both use a stop box!

I sincerely dont think that the ogive caliber or meplat diameter was an issue w the Hornadys.

The Kynoch 416 FMJ has a bit more streamlined ogive than the Hornady but they had identical pentration (plus or minus 1/2 board).

I did not even intend to test FN or any other bullet other than the Hornady. I even used Hornadys for the 375 and 416 so construction would be as close as possible.

The fact that a FN penetrates less in wood than a RN and just the opposite in an elephant head in no way invalidates the La Grange stop-box.

It accurately measures enery over unit of frontal area and is useful for comparing the penetration of bullets of different weight and caliber, so long as they use the same kind of bullet (RN or FN)!

You are using it the same way I would, to compare different FN bullets in your 470.

The wood stop box actually predicts the penetration of a FN in an elephant skull more accurately than water. My 450 Dakota w 1-12 twist penetrated 54 boards with air space = 81 inches vs. 120 inches water, compared to 60 inches actual elephant (3 shots) for a 450 grain NF FN.

RIP's composite set up is probably the only contraption in existence to hit it right on the head for both monometals, FN, RN, and soft points.

But you have to be one sick MF to build a rig like that! beer

I am not surprised Canucks 470 Mbogo did so well with Bridgers at just 1-14 twist. It has a SD the same as a 450 grain .458 (SD .300). A high velocity .416 or .458 gave up just a few boards penetration w 1-14 using SD <.300 bullets.

Big problem is with SD >.330 FMJ's and monometals like 400 grain 416 and 500 grain .458.

PS, I was surprised my 450 had so much more penetration than your 470. I thought we were using the same thickness of plywood (3/4 inch)? Or were you using solid boards?

Andy
 
Posts: 1278 | Location: Oregon | Registered: 16 January 2004Reply With Quote
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Ok 10 twist with 500,so what twist in the 416 Rigby?


_____________________________________________________


A 9mm may expand to a larger diameter, but a 45 ain't going to shrink

Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened.
- Winston Churchill
 
Posts: 5077 | Location: USA | Registered: 11 March 2005Reply With Quote
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Andy,
You and Rob have inspired me. Wink
The Iron Buffalo shall ride again.

1) 50 BMG with 1:15" twist Lothar Walther barrel:
loaded down to 2500 fps with 570-grain GSC FN

2) 500 A-Square with 1:10" twist McGowen barrel:
loaded up to 2500 fps with 570-grain GSC FN

3) .505 Gibbs with 1:10" twist McGowen barrel:
loaded up to 2500 fps with Bridger 525-grain brass FN solid.

(Yes, CZ uses a 1:10" twist barrel on their Safari Classic .505 Gibbs, made by McGowen, so add Harry to lineup with Ed, Art, and J.D. 15" Twit Raters may kiss their derrieres.)
moon moon moon moon

Will either 1, 2, or 3 make it all the way through this alternation of 1" of plywood with 7" of water layers, that is the question. A 4" thickness of wood can be piled in the last compartment, or even a steel plate to stop anything that gets that far. But that will not be likely.

 
Posts: 28032 | Location: KY | Registered: 09 December 2001Reply With Quote
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quote:
Originally posted by jwp475:
Ok 10 twist with 500,so what twist in the 416 Rigby?


jwp475,
Would you accept a hint from Don G in the FatLadySings post above?
 
Posts: 28032 | Location: KY | Registered: 09 December 2001Reply With Quote
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quote:
compare it to your own exhaustive research.


quote:
You, Dan, RIP, Norbert, Gerard, and I are the only ones who seem to be getting their hands dirty. (Or should I say wet?)


Andy, By your tone I think you have mistaken my inquisitive nature for a blatant challenge of your results. I truly appreciate the exhaustive efforts with bullet tests posted here on AR as it offers some interesting reading.

I was only trying to offer differing possibilities to your conclusion. After all, if a theory doesn't hold up to scrutiny then it isn't really a theory is it? Heck, for all I know maybe the world is still flat.
 
Posts: 436 | Location: Houston, Texas | Registered: 27 December 2005Reply With Quote
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Would that hint be 1X10?


_____________________________________________________


A 9mm may expand to a larger diameter, but a 45 ain't going to shrink

Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened.
- Winston Churchill
 
Posts: 5077 | Location: USA | Registered: 11 March 2005Reply With Quote
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quote:
Originally posted by jwp475:
Would that hint be 1X10?


jwp475,
The common twist is 14" for .416's of USA make. Gerard Schultz says the originals across the pond were 1:16.6" and don't work well with the longer 400 to 410 grain monometal copper, though they do good work with the shorter lead cored bullets.

From all we have learned about twist in the 500 A2, and from the fact that I have 3 rifles of .423 caliber with 10" twist that are excellent performers with bullets of all types from 320 grains to 400 grains, I would unhesitatingly recommend 1:10" twist if it can be had, or at least 1:12" for best performance with any hunting bullet.

I used a 1:12" twist for a .416 Dakota built on an M70 RUM-box action. I should have held out for a 10" twist.

George Hoffman opined that he would choose a 12" twist instead of 14".

We are learning.

Use a 1:10" twist and never will you regret it. 12" at slowest if your barrel maker doesn't offer 10".

Twit Raters rebuttal? sofa
 
Posts: 28032 | Location: KY | Registered: 09 December 2001Reply With Quote
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quote:
Originally posted by RIP:

1) 50 BMG with 1:15" twist Lothar Walther barrel:
loaded down to 2500 fps with 570-grain GSC FN

2) 500 A-Square with 1:10" twist McGowen barrel:
loaded up to 2500 fps with 570-grain GSC FN

3) .505 Gibbs with 1:10" twist McGowen barrel:
loaded up to 2500 fps with Bridger 525-grain brass FN solid.


Look out RIP! The non-believers are going to come for you... Smiler
 
Posts: 18352 | Location: Salt Lake City, Utah USA | Registered: 20 April 2002Reply With Quote
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quote:
Originally posted by jeffeosso:

Now, If you don't like your own quotes, perhaps you might contempt on the vagarities of "lying"

jeffe


500grains,
Does the above quote from jeffeosso indicate that English is his primary language?

I think not.

Give him a break, cut him some slack. It is just another pissers in the river that might have been beer induced, by the sorrow of realizing all those slow twist rifles need to be rebarreled for optimum function. Ouch! Wink

BTW, I will also load the 500 A2 down to 2150 fps with the 570-gr GSC FN in a 10" twist and see how good a 500 NE double would be with that twist.

And I could also keep uploading the 15" twist 50 BMG with 570-gr GSC FN until I get the penetration up to that of the 10" twist 500 A2 at 2500 fps. Wink

Maybe I will finally be able to blow through the last compartment of the Iron Buffalo.
 
Posts: 28032 | Location: KY | Registered: 09 December 2001Reply With Quote
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JMJ,

quote:
I think any scientist will tell you that it isn't an empirically sound or valid experiment if you have variables present. I am not saying your results don't prove anything but with the variables present you can't really say that it is a valid experiment.


Actually, you were sounding like an arm-chair expert.

But I appriciate the mea culpa.

RIP, rock on!

Andy
 
Posts: 1278 | Location: Oregon | Registered: 16 January 2004Reply With Quote
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quote:
Actually, you were sounding like an arm-chair expert.


I think context gets screwed up with the written ( or typed ) word.
 
Posts: 436 | Location: Houston, Texas | Registered: 27 December 2005Reply With Quote
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quote:
Originally posted by 500grains:
Get a clue Jeff. If your loads are too hot as a result of a change of twist, then your loads are TOO HOT. Safe loads will not give you any trouble regardless of the twist.



quote:
Originally posted by 500grains:
In fact I would not expect anything of the sort.


So, Dan,
Please answer the question, as you have made it clear that reading your posts in context can't be taken for a firm answer.

with the same load, does changing the twist increase the pressure?

If you don't mind, though, could you refrain from emotional outbursts in answering that simple question?

And, if changing twist has no effect on pressure, could you tell us why you are ranting about loads being too hot of a change in twist makes them over pressure? stir

RIP,
looking forward to your results, should be "interesting" to say the least



jeffe


#dumptrump

opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com
 
Posts: 38374 | Location: Conroe, TX | Registered: 01 June 2002Reply With Quote
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Brother RIP,

To demonstrate the folley of their ways, you may need to recover bullets that are marginally stable, not ones that are rocking along at 2,500 fps!



Not many of us here can handle a 570 grain at 2,500 fps. I know I cant!



Anyway you can try this with man-portable rather than crew-served 500 nitro load???



Like a 570 grain at 2,100 fps in both 1-10 and 1-15 twist???

JWP,

Using 410 grain Kynoch and 400 grain Hornady steel jackets, the .416 equaled the penetration of the high velocity 458's with a 1-10 twist.

Andy
 
Posts: 1278 | Location: Oregon | Registered: 16 January 2004Reply With Quote
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Jeff,

I think RIP shed light on the issue which I missed. You have designed the AR calibers and made several rifles based on them with slow twist barrels. Of course I understand your wish to defend that decision. Like you, I also built some custom rifles with standard/slow twist barrels. Unfortunately not all of us are born knowning that a fast twist maximizes penetration in large game. I wish I had been born with that knowledge. And further, although Mr. Alphin stated the desirability of a fast twist quite clearly, he camoflaged that wisdom with a sales pitch for the horriffic Coil-Check stock. Eeker So I am afraid that I also missed it the first time through.

Now, your question was whether a faster twist generates more pressure than a slow twist, if all variables are otherwise kept constant. I wish to preface my answer so that you do not run off making assumptions and then drawing conclusions based on the assumptions. The difference in pressure is not material. It would only matter if your reloads were already TOO HOT. And now for the answer. Yes, I would expect a small increase in pressure. But not enough to matter in a case that holds 80 to 110 grains of powder.

And now for my question: Do you now accept that increasing twist rate tends to increase penetration depth of solids in large animals?

If not, is there any data that would help you in reaching a position on this issue?

Keep in mind that 100 years ago, a Brit who had never hunted Africa selected a SLOW twist for the 470 NE. The result was so-so, but not optimal. Shall we repeat the mistake 100 years later?
 
Posts: 18352 | Location: Salt Lake City, Utah USA | Registered: 20 April 2002Reply With Quote
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Picture of 470 Mbogo
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Hi Andy,
I don't know if you have read through my website on the Comparing The Big Bores section. But if you are finding a difference in penetration it is explained there and you will find that it is due to bullet nose shape. I used Barnes Solids for the testing of all calibers to keep the nose shapes the same except for the 450 Ackley at 2400 fps. This was due to the long Barnes bullet eating up so much powder space that the 2400 fps velocity could not be reached. The solution was to use the Hornady FMJ 500 grain bullet to reach the velocity. To prove the difference in penetration due to nose shape I loaded the 470 Mbogo with the Woodleigh 500 FMJ bullet which had the same basic nose shape as the Hornady. The penetration difference was quite a bit deeper with the Hornady nose shape compared to the Barnes nose shape. So if your noticing a difference in penetration depths between my tests and yours, I would look into the nose shape of your solids. My test box was made of 3/4 plywood with a 3/4 air space inbetween the squares of plywood. The plywood squares were locked in on three sides so they stayed in place during the testing so the bullets holes from previous shots never interfeered with following shots.
Take good care,
Dave
 
Posts: 1247 | Location: Sechelt B.C. | Registered: 22 May 2002Reply With Quote
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Picture of 470 Mbogo
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Hi Andy,
Quote "A slight increase in rotatioal velocity as you suggest for the Barnes bullets will not help at all. I could not stabilize a 500 grain Barnes X in either water buckets or wood stop box with even a 1-10 twist at 2,350 fps. (It turned over 180 degrees by the 23rd board and went base forward to the 28th. An "over-stabilized" FMJ RN would go 72 boards"

I think you may find that this particular bullet might have been stabalized fine and that it's the changing nose shape of a soft point that is causing the tumbling. That is why you can't really compare soft points with this kind of testing.
When I tried the wet news paper testing I soaked each piece of paper individually in a wheel barrow full of water. It is just a very poor test medium.
Take good care,
Dave
 
Posts: 1247 | Location: Sechelt B.C. | Registered: 22 May 2002Reply With Quote
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Dave,

I checked out your web site earlier today as I had not read it for awhile, but got stuck on the video!

My reference standard for all calibers was the Hornady and yours was the Barnes, so we both had consistant bullet types.

You have confirmed what Dan found, which is that the Barnes always has less penetration than the Woodleigh, Hornady or, in elephant, a monometal FN.

I have no idea why, but it keeps comming up that way.

I also used 3/4 inch plywood spaced 3/4 inch apart, so difference must be Barnes vs Hornady combined with the lower FA of a .458.

The 500 grain Swift soft point certainly did well on the buff, and the Bridger FN took alot of abuse taking out a foot of spine!

I would be happy to have a rifle like that.

Thanks for sharing.

Andy
 
Posts: 1278 | Location: Oregon | Registered: 16 January 2004Reply With Quote
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Picture of jeffeosso
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Dan,
what was the twist of these rifles and do you consider the twists to be too slow for effective penetration?

quote:
Originally posted by 500grains:
GS Custom flat nose copper bullets. Available from www.gscustom.co.za

From left (all GS Custom):

(1) unfired 570 grain 500 Nitro Express bullet
(2) 570 grain 500 NE bullet fired into elephant (frontal brain) - penetrated 74 inches, but missed neck vertebrae
(3) 570 grain 500 NE bullet fired into elephant (frontal brain) - penetrated 31 inches and stuck in neck vertebrae
(4) 570 grain bullet fired into buffalo (body shot) - penetrated 60 inches
(5) unfired 500 grain .470 Capstick bullet
(6) 500 grain .474" bullet fired into buffalo (body shot) - penetrated 56"
(7) 500 grain .474" bullet fired into giraffe (body shot) - penetrated 40"





#dumptrump

opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com
 
Posts: 38374 | Location: Conroe, TX | Registered: 01 June 2002Reply With Quote
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Jeffe,

Having read thru this longwinded thread, I fail to see how you could misunderstand 500grains meaning in his various posts. They seem clear to me, and English is not my first language!

Thus, I can only conclude that you have intentionally misread his posts, just to stir up shit. thumbdown

Isn't there enough BS elsewhere on AR? Why does it have to filter over to this forum too? Frowner
 
Posts: 2662 | Location: Oslo, in the naive land of socialist nepotism and corruption... | Registered: 10 May 2002Reply With Quote
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Picture of 470 Mbogo
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You know all this twist rate may be a moot point as all my rifles from 1:14 to 1:10 keep tipping things over. Penetration has never really been a problem. Bullets have been the bigger problem but with the high quality of bullets a person has to choose from it isn't much of a problem either. Solids have improved tremendously so that's no longer a real problem. Lets just shoot and have a good time and quite picking fly shit out of pepper.
Take good care,
Dave
 
Posts: 1247 | Location: Sechelt B.C. | Registered: 22 May 2002Reply With Quote
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