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4seventy
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Reged: 07/05/03
Posts: 2210
Loc: Queensland Australia
577 Questions
      #53460 - 28/03/06 02:12 PM

Regarding the building of a .577 Nitro double using the 650 grain bullet hopefully at 2000 fps or thereabouts, here are a couple of questions.

1 What would be your estimate on the minimum safe chamber wall thickness required when using a monobloc system?

2 Would there be any real benefit in using the 3 inch case rather than the 2 3/4 inch case?
Pressure would be lower but achieving maximum loading density/reliable ignition may be more of a problem?

3 What should the minimum rifle weight be? (double rifle of course)

Thanks

Edited by 4seventy (28/03/06 03:29 PM)


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Marrakai
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Reged: 09/01/03
Posts: 3475
Loc: Darwin, Top End of Australia
Re: 577 Questions [Re: 4seventy]
      #53493 - 28/03/06 10:53 PM

Alan:
Can't answer all your questions, but I do have more than a passing interest in this cartridge and can offer a few thoughts.

If you are prepared to drop the velocity a little, you are talking about the ol' .577/90/650 load. According to the 1926 ICI catalogue that load managed 1950 fps (5500 ftlbs ME) in a 28-inch barrel with less than 10 tons pressure.

The 1902/3 Kynoch catalogue gives it 2000 fps from a 30-inch barrel using the 3-inch case, at 10 tons even.

Pondoro Taylor waxes lyrical about the .577/75/650 load, which is listed by Kynoch as the top 'nitro-for-black' load in the 3-inch case, achieving 1850 fps (probably also from a 30-inch barrel) at under 10 tons.

Since none of these loads exceed 10 tons, the chamber-wall measurements from any .577 BP Express rifle should be good enough, with a generous margin for error on account of modern steels in a newly-built gun.

Weight will probably need to be 11 lbs minimum for the 90-grain (cordite equivalent) load, Taylor reckons 10.5 lbs would be OK for the 75-grain equivalent load. I think he's right. My Greener .577 conversion is regulated for the 65-grain load, and although a little stout is very comfortable to shoot at 10.5 lbs.

I have stated before that a major advantage of the 2 3/4 case IMHO is that no-one can ever load a full nitro .577/100/750 cartridge at 14 tons pressure and spontaneously disassemble your handiwork! True, pressure will probably be slightly lower with the 3-inch case, but you will need more wads. Since you will need some wads or filler in the 2 3/4 case anyway, this probably doesn't mean much. Your call.

Every now and then a mischevious little demon whispers in my ear to try heavier loads in my Greener, but so far I have resisted, which has no doubt contributed to the longevity of both the gun and the shooter I'm sure!

--------------------
Marrakai
When the bull drops, the bullshit stops!
--------------------------------
www.marrakai-adventure.com.au


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CptCurlAdministrator
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Reged: 01/05/04
Posts: 5268
Loc: Fincastle, Botetourt County, V...
Re: 577 Questions [Re: Marrakai]
      #53494 - 28/03/06 10:59 PM

Marrakai,

Did you do your conversion yourself or have it done professionally. I was wondering if there is a qualified gunmaker doing this type work, or are we all in reliance of "backroom" work?

I've always had a hankering for a .577 light nitro. Better yet, a really nice .577 BPE. Every time I get close, the quarry skips away or remains out of reach.

Curl


--------------------
RoscoeStephenson.com

YOUR DOUBLE RIFLE IS YOUR BEST FRIEND.



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Marrakai
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Reged: 09/01/03
Posts: 3475
Loc: Darwin, Top End of Australia
Re: 577 Questions [Re: CptCurl]
      #53498 - 28/03/06 11:31 PM

Curl:
I am the third owner of that Greener .577. It was commissioned by Les O_ in Melbourne, who kept it for a year or two, and killed a buff or scrub bull or two with it. It was then offered for sale, and I nearly bought it but was on the trail of a Webley boxlock .577/75/650 so turned it down. It was then bought by Tim C_ in the UK. After another year or so, Tim needed to swap it for money, I had lost the deal on the Webley in the meantime, so back to Australia it came!

The work was originally done by Rolph Bachnik (not sure of spelling) who was Saunders' gunsmith at Century Arms/ London Guns. He is pretty good with the old pommie stuff, especially restoring/ rebuilding/ refaking! (Oops, typo, I meant remaking!) He built several of these Greener conversions, some were cape guns, all were successful. They are very professionally made, certainly not back-yard standard, mine even has a faceted diamond for a foresight bead! Rolph has his own shingle now since Century Arms closed, might be called Safari Arms IIRC.

My rifle has 22-inch barrels which are a little heavy at the muzzles. If I was to commission such a rifle myself, I would go for 24-inch tubes with much slimmer muzzles and try to get some weight back in the action. Not sure how to do this, I have even pondered glueing a lead-filled steel tube (or a depleted uranium rod!) into a hole bored centrally into the wrist from inside the stock-head. I know it is a simple matter to add lead or mercury reducers in a hole bored under the recoil pad, but that would kill the handling just as surely as heavy muzzles IMO.

I'm dribbling on again, sorry, but you will agree these things are important!!

--------------------
Marrakai
When the bull drops, the bullshit stops!
--------------------------------
www.marrakai-adventure.com.au


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4seventy
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Reged: 07/05/03
Posts: 2210
Loc: Queensland Australia
Re: 577 Questions [Re: Marrakai]
      #53500 - 29/03/06 12:09 AM

Tony,
Glad you responded to this one as I know you've been "dancing" with this cartridge for a while now.
Here's the basic plan.
I really would like to build a 5500-6000 ft lb 577, something like a "heavy nitro 650 gn bullet" load, for want of a better term.
Maybe 95-100 cordite equivelant but with the 650 gn bullet.
I realize that the pressure is going to be up there a bit and that was the reason for considering the 3" case.
With the 12 gauge frame and monobloc I'm thinking of using I will only be able to get about 235 to 240 thou max chamber wall thickness.
Not at all sure if that will be enough so will have to do the calculations.
I'm certain I can get the weight to at least 11 pounds and hopefully 11 1/2 and still maintain good balance etc.
I've had this idea in my head ever since reading your fat lady story and have been planning and figuring and measuring and drawing and calculating for some time.
It is still all just a dream at this stage.




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mickey
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Reged: 05/01/03
Posts: 4647
Loc: Pend Oreille Valley, Idaho
Re: 577 Questions [Re: 4seventy]
      #53513 - 29/03/06 02:11 AM

Alan

I have a 577/2.75/750 Hollis. It shoots at 1850 and is a wonderful rifle. It weighs in at 10 pounds and generates about 5500/ft/lbs.

I don't know the pressure but it should be listed in a Kynoch Catalog.



--------------------
Lovu Zdar
Mick

A Man of Pleasure, Enterprise, Wit and Spirit Rare Books, Big Game Hunting, English Rifles, Fishing, Explosives, Chauvinism, Insensitivity, Public Drunkenness and Sloth, Champion of Lost and Unpopular Causes.


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BlainSmipy
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Reged: 24/11/05
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Re: 577 Questions [Re: Marrakai]
      #53541 - 29/03/06 07:30 AM

*



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4seventy
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Reged: 07/05/03
Posts: 2210
Loc: Queensland Australia
Re: 577 Questions [Re: mickey]
      #53548 - 29/03/06 09:43 AM

Mick,
Would love to know the chamber wall thickness on that rifle if you get a chance to measure it.
Thanks


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banzaibird
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Reged: 18/09/05
Posts: 358
Loc: S.C. Pennsylvania, USA
Re: 577 Questions [Re: 4seventy]
      #53549 - 29/03/06 09:46 AM

Mick,

As well as other barrel profile measurments. Say every 3-4 inches along the lengths of the barrels? If you are willing of course.

Bill


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Marrakai
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Reged: 09/01/03
Posts: 3475
Loc: Darwin, Top End of Australia
Re: 577 Questions [Re: banzaibird]
      #53686 - 30/03/06 11:48 PM

4seventy:
Finally got around to measuring the chamber wall thickness of my Alex Henry 20-bore/.577 Express. It's in the order of 220 thou, and damascus remember.

Even though this case is bottle-neck (like a .577/.500 on steroids!), it is only 2 3/4 inches long so it still has a similar case-volume to the .577 x 3-inch Express, and identical ballistics. I think we can safely assume it turned-up around 10 tons of pressure with the original 167gr BP load.

This would make your 235 to 240 thou of modern steel seem quite adequate. Dunno whether I'd press for the 95-100gr cordite equivalent though, it might just be pushing the pressure/ recoil/ gun-weight combo beyond comfortable limits. Having seen what the 65gr-equivalent load does to buffalo, boars, and feral horses, I think you could be quite pleasantly surprised by the all-round utility of a .577/75/650 to 577/90/650 double. The latter load generates damn near 5500 ftlbs, which is your target ME anyway.

Just be sure and let us know what you decide. You'll get plenty of heckling from the gallery either way!

--------------------
Marrakai
When the bull drops, the bullshit stops!
--------------------------------
www.marrakai-adventure.com.au


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4seventy
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Reged: 07/05/03
Posts: 2210
Loc: Queensland Australia
Re: 577 Questions [Re: Marrakai]
      #55113 - 18/04/06 03:53 PM

Marrakai,
Thanks heaps for that information.
I'll keep you posted.


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NitroXAdministrator
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Reged: 25/12/02
Posts: 39055
Loc: Barossa Valley, South Australi...
Re: 577 Questions [Re: 4seventy]
      #341663 - 03/06/20 09:06 PM

Tags: ".577 Light Nitro" ; ".577 LNE" ; ".577 NE" ; ".577 Nitro Express" ;

--------------------
John aka NitroX

...
Govt get out of our lives NOW!
"I love the smell of cordite in the morning."
"A Sharp spear needs no polish"


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