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Double Rifles, Single Shots & Combinations >> Double Rifles
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hoppdoc
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New Double Cartridge needed??
      #80813 - 17/06/07 11:18 AM

There seem to be innumerable Double cartridges and one wonders are there any gaps to be filled??

For short range open sight Double scenarios (150 yds or less)it would seem no gaps exist---

Once we consider scopes on Doubles and their capabilities for long range accuracy gaps may materialize--

***If one where to develop an American all round Double I would think a 30 cal wildcat based on the 7x65R shooting 180 gr bullets(a rimmed 30.06 equivilent)would have appeal.It could feature true ejectors, a qd scope and other features(read expensive!!) high end hunters would desire/appreciate.

For those who would hunt elk/moose/grizzly a 338 caliber would be great.The 333 Jeffery Flanged in 338 would be fun or maybe even the 375 H&H Flanged necked down to 338 caliber!!

Does anyone else want to wildcat a Double cartridge for a specific hunying purpose??

What wildcat would you create??

--------------------
An armed man is a citizen of his country, an unarmed man just a subject.

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500Nitro
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Re: New Double Cartridge needed?? [Re: hoppdoc]
      #80815 - 17/06/07 11:43 AM



(a rimmed 30.06 equivilent)


It's called the 307 Winchester.

I think we are re inventing the wheel ??????

Plenty of calibres fit the bill.

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hoppdoc
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Re: New Double Cartridge needed?? [Re: 500Nitro]
      #80820 - 17/06/07 12:24 PM

If 307=30.06 then great!!What would be the Double equivilent of

270
7mm Mag?
300WM=300H&H flanged?
338WM?

--------------------
An armed man is a citizen of his country, an unarmed man just a subject.

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Sarg
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Re: New Double Cartridge needed?? [Re: hoppdoc]
      #80824 - 17/06/07 02:57 PM

500Nitro, I see you like to correct people on even the smallest things ,so you will find the 307 Win is a slightly less powerfull version of the 308 Win !

hoppdoc ,there is a cartridge called - 30R Blaser which I believe is more powerfull than 30-06 .
Blaser use it in there single shots & double rifles !

Thanks

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EricCioe
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Re: New Double Cartridge needed?? [Re: Sarg]
      #80826 - 17/06/07 03:54 PM

If your criterion for "double rifle cartridge" is that it is rimmed so that it cna be reliably ejected, I have two questions:

1. If it's a long range cartridge, it's not a life-and-death thing if it doesn't eject. That said, there are many here that feel that rimless cartridges eject just fine. I'd like to read what people have to say about that.

2. But I can see why you'd want it to eject every time, so question 1 is a bit void. Still, it seems like it would easier if rifle-makers could come up with a way to eject rimless cartridges reliabely than to keep using bizarre, wildcatted ammo that simply replicates a standard load anyway. Why have a rimmed .30-06 equivalent if a standard .30-06 could be ejected fine, with a new system?

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hoppdoc
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Re: New Double Cartridge needed?? [Re: EricCioe]
      #80828 - 17/06/07 10:03 PM

I would agree that if a reliable ejection/extraction system could be devised using the belt of the "belted" magnums out there that the need for new cartridges would be seriously affected.

Love to have real ejectors on a 7mm mag,a Weatherby 416 etc,a and the multitude of belted cartridges we presently shoot in the states.

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bonanza
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Re: New Double Cartridge needed?? [Re: hoppdoc]
      #80835 - 17/06/07 11:19 PM

Any double rifle cartridge needs to keep pressure in check if one expects it to last. 20 tons is the absolute maximum, 15 tons is much better. With that in mind one should go for a medium caliber and a large case.

I’ve have the opportunity to experiment with my .375 H&H. Stepping down to a 235gr bullet, using H414 powder and finding the slowest regulation load – I have reduced the pressure way back.

Based on that, I reckon that a 300 UM case necked up to .350 shooting a 220 grainer at 2700 fps might fit the bill.

--------------------


"Speak Precisely" G. Gordon Liddy.

"Life is absurd, chaotic and we must define its purpose with our actions" Abert Camus

"I''m the dude playing a dude disguised as another dude."

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hoppdoc
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Re: New Double Cartridge needed?? [Re: bonanza]
      #80836 - 18/06/07 12:37 AM

Stupid question--

It has been discussed here before but what predictive relationship can be made between the cartridge pressure in tons and the cartridge pressure in copper units or other methodology?

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500grains
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Re: New Double Cartridge needed?? [Re: hoppdoc]
      #80837 - 18/06/07 12:52 AM

There have been a handful of doubles made in 30-40 Krag.

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bonanza
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Re: New Double Cartridge needed?? [Re: bonanza]
      #80845 - 18/06/07 03:13 AM

Short answer - none. As long as the methods are linear then a % pressure change due to a charge change will yield the same % in another method.

Hodgdon gives most loads in CPU and Birmingham Proof House uses tones. I think tones times 2200 is close to PIS, not certain.

When working up a load for my .375 I pick the one that was the LEAST, and then reduced it 10%.

One think I have noticed in published pressure is that the last 2-300 fps requires non-proportional pressure.

Accepting 2300 fps instead of 2500 in a .375 knocks close 10% off the pressure.

Modern bullets work well at lower velocities and for short range hunting, why not reduce velocity and save you double rifle.

--------------------


"Speak Precisely" G. Gordon Liddy.

"Life is absurd, chaotic and we must define its purpose with our actions" Abert Camus

"I''m the dude playing a dude disguised as another dude."

"Yo! Mr. White"

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hoppdoc
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Re: New Double Cartridge needed?? [Re: bonanza]
      #80850 - 18/06/07 05:38 AM

Again, it may not be linear but Kynoch says the 416 Rigby is at 18 tons with 410gr at 2300+fps.

A loading site lists a similar weigh/velocity with ??powder at 42,000 cup which is of course not equivilent to psi.

Looks like 42,000 may be the max cup pressure for 18 tons or does the tonnage also vary with the diameter/surface area of the hull enclosedby the barrel??

Any engineers or gee whiz guys out there can sing in anytime!!

--------------------
An armed man is a citizen of his country, an unarmed man just a subject.

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bonanza
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Re: New Double Cartridge needed?? [Re: hoppdoc]
      #80851 - 18/06/07 06:38 AM

You may have noticed that most of the double rifle cartridges are launching the projectiles at or near 2150 fps. The amount of pressure to do this is dependant on the case volume. A 458 WM produces 18 tones and a 450 No2 11 tones to attain the same velocity. A quick study of the Ideal Gas Law (PV=nRT) will shed some light.

In regards to a break open action, the back thrust of the case causes the frame to asymmetrically flex and stretch. It’s this tweaking that contributes to a rifle coming of face.

When one starts talking about high velocity small bore cartridges, high pressure becomes the bug-a-bear.

A .350 cartridge with the ballistics of a .35 Whelan and pressure of a 450-400 is darn near ideal in my book. It’s called the .350 Rigby

--------------------


"Speak Precisely" G. Gordon Liddy.

"Life is absurd, chaotic and we must define its purpose with our actions" Abert Camus

"I''m the dude playing a dude disguised as another dude."

"Yo! Mr. White"

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Mike_McGuire
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Reged: 11/06/05
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Re: New Double Cartridge needed?? [Re: bonanza]
      #80860 - 18/06/07 08:32 AM

Big Bore pressure Vs small bore pressure??

Assume we load a 458 Lott and 300 Wby to the same pressure or a 458 Win and 257 Wby to the same pressure. Also assume the amount of powder being used in both big and small bores is the same.

Then if the peak pressure is the same for both big and small bores the average pressure will be higher with the small bores and by a considerable margin.

Is that a factor?

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hoppdoc
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Re: New Double Cartridge needed?? [Re: Mike_McGuire]
      #80864 - 18/06/07 10:43 AM

Wouldn't the same weight bullet/same velocity pressure curves of something like the 416 Rem vs 416 Rigby show the 416 with a higher shorter duration curve for the Rem vs a lower longer duration pressure curve for the higher volume case of the Rigby??

Is "tonnage" or cup/psi etc just suggestive of the peak pressure of each round?

Would the area under each curve be similar if the bullet velocity was the same??

I am speculating here, so somebody correct me if I'm confused---

--------------------
An armed man is a citizen of his country, an unarmed man just a subject.

Edited by hoppdoc (18/06/07 10:44 AM)

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Mike_McGuire
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Re: New Double Cartridge needed?? [Re: hoppdoc]
      #80871 - 18/06/07 11:32 AM

Wouldn't the same weight bullet/same velocity pressure curves of something like the 416 Rem vs 416 Rigby show the 416 with a higher shorter duration curve for the Rem vs a lower longer duration pressure curve for the higher volume case of the Rigby??

Is "tonnage" or cup/psi etc just suggestive of the peak pressure of each round?

I think that is correct.

However, a consideration is that it will require a certain amount of pressure for something "to give". For example, one hot load and you have a loose primer pocket but 20 shots of mild loads and the primer pocket remains tight.

Average pressure or pressure under the curve would increase with a longer barrel

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Ripp
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Reged: 19/02/07
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Re: New Double Cartridge needed?? [Re: hoppdoc]
      #80875 - 18/06/07 12:27 PM

Quote:



Would the area under each curve be similar if the bullet velocity was the same??

I am speculating here, so somebody correct me if I'm confused---






The pressure curve would not necessarily be the same--the .416 Rigby has a larger case than the .416 Remington and therefore operates under lower pressure than the Remington round--and yet they are both shooting around 2400 fps. This is one reason some knock the .416 Remington for hunting during the really hot time of year in Africa--personally I have probably shot 50 plus rounds of .416 Remington while hunting in Africa with no problems what so ever and fantastic performance on everything I pointed it at..

Ripp

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bonanza
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Re: New Double Cartridge needed?? [Re: hoppdoc]
      #80886 - 18/06/07 09:56 PM

Whether it is tones, CUP, or PSI – the instrumentation is designed to generate a reproducible value representing “pressure” at a given velocity. That value could be anything including bananas, as long as it is consistent and linear.

The area under the curve and shape of the curve depend on the burn rate of the propellant, and can only be explained with black magic.

However; in Graeme Wrights book he touches on medium versus slow powered. He suggests that slow powders may carry too much pressure in the thin area of the tubes and that medium power like R15 reach peak pressure in the first 6 to 8 inches where the barrels are strongest. Makes sense to me

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bonanza
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Re: New Double Cartridge needed?? [Re: Mike_McGuire]
      #80888 - 18/06/07 10:15 PM

The Ideal Gas Law PV=nRT states pressure is inversely proportional to volume. If we assume nRT is a constant c then P = c/V.

If we let c equal the chemical reaction of the propellant and call it 1000;

then for a .300 cal that has traveled 5” down the barrel, P = 1000/(.300Pi*5) = 210

for a .458 cal P = 1000/(.458Pi*5) = 140

For the same gas generated by the propellant, the pressure is less in a big bore. Conversely, to reach the same velocity, more propellant is needed.

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Ripp
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Re: New Double Cartridge needed?? [Re: bonanza]
      #80890 - 18/06/07 10:45 PM

Quote:


For the same gas generated by the propellant, the pressure is less in a big bore. Conversely, to reach the same velocity, more propellant is needed.



Exactely...
Ripp

--------------------
ALL MEN DIE, BUT FEW MEN TRULY LIVE..

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dnovo
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Re: New Double Cartridge needed?? [Re: Ripp]
      #80895 - 18/06/07 11:06 PM

Again we seem to be trying to get a DR to do the work it was never intended to carry out. Long range, flat shooting rifles exist aplenty in bolt actions without trying to consider making a DR fill that role. And while one can get very good accuracy out of a DR, and my W&S in 250-3000 and Merkel 141 in 30-06 are quite accurate out to a reasonable range, why make a design intended for dangerous game or 'meat pot' filling out to 100 or 150yds max work as a Benchrest or Mountain Goat slayer? A bolt costing far less will always function better at longer ranges and a follow up shot with a good bolt action at long range will be only a hair slower if you take the time to learn your rifle.

I shot in informal 300 meter CISM competition with some other elderly farts. Using a Grunig & Elmiger and open sights for the first round (yes I can still do so despite my years) a ten round string within time limits results in a very presentable group. Take the Anschutz diopter sight off the rail and slide on a 36X Weaver target scope and this old fart can still make 10 timed rounds of 6.5X47 Lapuas go into one ragged hole at 300. I have seen others do the same with off-the-shelf Remington 700s.

So let's not get lost trying to turn a good short to medium range DR into what it was never designed for.


Dave

--------------------
Time Wounds All Heels

Edited by dnovo (18/06/07 11:08 PM)

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Tatume
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Re: New Double Cartridge needed?? [Re: dnovo]
      #80916 - 19/06/07 05:49 AM

> If we assume nRT is a constant c then P = c/V.
> If we let c equal the chemical reaction of the propellant and call it 1000;
> then for a .300 cal that has traveled 5” down the barrel, P = 1000/(.300Pi*5) = 210
> for a .458 cal P = 1000/(.458Pi*5) = 140

The volume of a right circular cylinder is V = hPi r^2 (height times Pi times radius squared). The calculation then yields
30 cal: P = 1000/5(Pi*(0.154)^2) = 2684
45 cal: P = 1000/5(Pi*(0.229)^2) = 1214

Take care, Tom

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bonanza
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Re: New Double Cartridge needed?? [Re: Tatume]
      #80919 - 19/06/07 06:48 AM

Thanks Tom,

I was pulling that out of memory, PiR^2 not 2PiR!

But that is important because pressure is actually inversely proportional to the square of the radius. Which really kills the notion of a high velocity small bore being practical in a double rifle

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AzGuy
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Re: New Double Cartridge needed?? [Re: bonanza]
      #80923 - 19/06/07 10:11 AM

Quote:


But that is important because pressure is actually inversely proportional to the square of the radius. Which really kills the notion of a high velocity small bore being practical in a double rifle



All of this math is hurting my brain. Guess I'd better call Butch and cancel the order for the 257Wby SxS.

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Hike the Grand Canyon, you will never be the same!

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400NitroExpress
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Re: New Double Cartridge needed?? [Re: hoppdoc]
      #81011 - 20/06/07 03:28 PM

Quote:

Stupid question--

It has been discussed here before but what predictive relationship can be made between the cartridge pressure in tons and the cartridge pressure in copper units or other methodology?



There isn't one because they're measurements of different things.

With respect to the original standards of the British rifle cartridges, "tons" is a measurement of bolt thrust. The British ignored chamber pressure. They standardized their rifle cartridges in base crusher guns that measured bolt thrust using the Base Copper Unit of Pressure yardstick, with the result expressed in "tons" - 2240 pounds/ton. CUP (Copper Unit of Pressure) and the current BAR/PSI are radial measurements of chamber pressure measured by crusher and piezo electric transducer methods respectively. None of the three are convertible to each other.

No, the Birmingham Proof House doesn't use "tones". The old standards have been out of use for 18 years. Britain is now a member of CIP and their proof laws are now standardized on the CIP mandated chamber pressure measured by piezo electric transducer, expressed in BAR. Most of the old British rifle cartridges have been standardized by CIP, and the old bolt thrust standards have been laboriously converted to current chamber pressure methodology. Since bolt thrust varies with regard to case dimensions, the current standards can be surprising to some. For example, the .450 No. 2 NE, at 13 tons, had the lowest "pressure" of the large, full nitro, flanged cartridges, but it's chamber pressure is far from the lowest.

.450 No. 2 NE = 13 tons. Current CIP MAP = 2800 BAR/40,610 PSI
.470 NE = 14 tons. Current CIP MAP = 2700 BAR/39,160 PSI
.500/.465 NE = 14 tons. Current CIP MAP = 2450 BAR/35,534 PSI

BaseCUP (tons) and CUP are both long obsolete.

--------------------
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hoppdoc
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Re: New Double Cartridge needed?? [Re: 400NitroExpress]
      #81019 - 20/06/07 08:10 PM

Fantastic!!

Can we assume that 40,000 psi is a safe pressure for a quality Double action or can we go higher in medium calibers?

What are the limits for quality medium Doubles with regard to psi?

How about the obsolete "tons" of backthrust?

I believe the 30.06 runs about 52,000 psi.

How about limits of a 300 ultramag at 52,000 psi or 40,000 psi (normal up to 62,000 psi) in a Double shooting a 200 gr bullet?? Any way to predict Double survival other than to just do it/shoot it??

--------------------
An armed man is a citizen of his country, an unarmed man just a subject.

Edited by hoppdoc (20/06/07 08:14 PM)

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