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Glenn_Fewless
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Reged: 08/05/08
Posts: 103
Loc: Wisconsin, USA
.577 2-3/4" barrel shank diameter
      #124366 - 18/01/09 04:44 AM


Gentlemens:

I have recently acquired an early Gibb Farquharson action that is alleged to have been originally chambered in .577-450, and the extractor dimensions support this. The .577-.450 is an anomaly in Gibbs rifles and a chambering that doesn't interest me. Only the action exists and from the two digit serial number I would estimate a born on date in the late 70's

From what I can gather it seems that about this time Gibbs offered his Gibbs .461 #1 and #2, the .500 Express and the .577 2-3/4". Of these the one that interests me the most is the .577.

Howsomever, this is a standard size action with a 1" diameter barrel thread. My question is if this is large enough of a barrel shank to chamber in .577? Assuming the it was chambered for the .577-.450 (per Kirton and the extractor) the .577 case should be no more of a burden on the barrel as it is the same diameter as the .577-450 at the barrel shank.

Any insight you gentlemen can offer would be most welcome. If anyone has a falling block .577 I sure would be interested to learn the barrel shank diameter. Also, if anyone has a BP double rifle it would be instructive to learn the wall thickness of the chambers. Any information would be greatly appreciated.

Thanks!

Glenn

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peter
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Reged: 11/04/07
Posts: 1493
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Re: .577 2-3/4" barrel shank diameter [Re: Glenn_Fewless]
      #124373 - 18/01/09 06:04 AM

Quote:


Gentlemens:

Any insight you gentlemen can offer would be most welcome. If anyone has a falling block .577 I sure would be interested to learn the barrel shank diameter. Also, if anyone has a BP double rifle it would be instructive to learn the wall thickness of the chambers. Any information would be greatly appreciated.

Thanks!

Glenn




hi glenn

my a. henry 20/577 has a barrel wall thickness of 5,4 mm, the load this thickness should contain is 7 drams of black with a 560 grains head over it

best regards

peter

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Bramble
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Reged: 29/07/06
Posts: 950
Loc: England
Re: .577 2-3/4" barrel shank diameter [Re: peter]
      #124377 - 18/01/09 06:18 AM

I take it you are refering to .577 2 3/4 BPE ?

From the info I have the Gibbs Farquharson is .985 Major 14 Tpi ?

A Ruger #1 is 1" major 16 Tpi

If the barrel is modern steels then IMO it should not be a problem.

If however you are going up to .577 NE I would have the action magnafluxed and/or x-rayed first.

Regards

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Glenn_Fewless
.300 member


Reged: 08/05/08
Posts: 103
Loc: Wisconsin, USA
Re: .577 2-3/4" barrel shank diameter [Re: Bramble]
      #124390 - 18/01/09 09:38 AM

Peter:

Thank you for taking the time to measure your rifle. It is much appreciated. 5.4 mm = .212", which is a lot thicker than what would remain at the minor diameter of a 1" thread.



Bramble:

Definitely a BP chambering. I would not trust the steel in the receiver ring of any rifle of that vintage to help hold the pressure, let alone one that is cut away as much as the Farquharson is. One of the reasons I am looking at the 2-3/4" chambering instead of the 3" is that it would be more difficult to come up with a full nitro cartridge to chamber in it.


From the info I have the Gibbs Farquharson is .985 Major 14 Tpi ?


I have not carefully measured the diameter yet. It looks like 1" so I am sure you are right. Rough measurement suggests that the wall thickness at the minor diameter of the thread will be only .130", which seems pretty modest. Howsomever, there were a lot of Martinis chambered in .577-.450 and I don't think they had larger thread diameters. Do you happen to know what the thread size was in the Martini action?

Thanks for your help. I want to restore this action into something it might have been. It probably was an MBL but it will be a sporting rifle when reincarnated.


Best regards,

Glenn

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Bramble
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Reged: 29/07/06
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Loc: England
Re: .577 2-3/4" barrel shank diameter [Re: Glenn_Fewless]
      #124394 - 18/01/09 11:23 AM

1" major 14 Tpi and I would imagine that it is a 55degree thread.

Check the thread pattern on the Gibbs, I would also expect it to be 55 degrees, NOT the US and European 60degrees.
To give you the safest rebarrel on this old action check this and cut the thread tight, then lap the threads in ( 320 -400 paste tighten-undo, tighten-undo and repeat until the barrel seats). It will only take 10-15 mins, but it does ensure that the pressure is evenly spread all around the breach on fireing.

Regards

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Glenn_Fewless
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Reged: 08/05/08
Posts: 103
Loc: Wisconsin, USA
Re: .577 2-3/4" barrel shank diameter [Re: Bramble]
      #124399 - 18/01/09 12:46 PM

Bramble:

Thanks! I forgot about the 55* thread! I will check that and may have to grind a tool. Or are you talking about using a 60* tool and lapping the threads to fit?

Glenn

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belgmart
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Reged: 29/02/04
Posts: 78
Re: .577 2-3/4" barrel shank diameter [Re: Glenn_Fewless]
      #124439 - 19/01/09 01:14 AM

A martini is 1" - 14 TPI, 55 degree thread. And if you cleaned up the chamber design of 577-450, I'm quite sure you would have something nice, but it would for sure require a custom reamer.
Another option is - remember - 500/450 #2 Musket, my favourite. Much more reasonable, and it was both a target and hunting round of considerable repute in the "good old days"... In order to make sure of a good brass supply, you might consider using the .50-90 or -110 as a base.

--------------------
Martini's Rule!

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Bramble
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Re: .577 2-3/4" barrel shank diameter [Re: belgmart]
      #124462 - 19/01/09 05:13 AM

Glenn.

No, cut the threads with a 55 degree tool, but cut them a little short of full depth, so that the thread starts but makes just makes a tight 1-1 1/2 full revolutions. Then apply the paste and lap in til the barrel nips up. If you don't want to grind the tool I believe that Brownells stock one.

Regards

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Glenn_Fewless
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Reged: 08/05/08
Posts: 103
Loc: Wisconsin, USA
Re: .577 2-3/4" barrel shank diameter [Re: Bramble]
      #124464 - 19/01/09 05:44 AM


Mr. Bramble:

Thank you again. I do fit barrel threads very close, but have never tried lapping them in. I may just experiment with that. Howsomever, even with a perfect barrel fit there is so little metal left in the Farquharson receiver ring, from the extractor cuts, that I would not count on getting any extra strength from there.

I will have a look at Brownell's for the cutter. That would save setting up and grinding one.


Mr. Martini Guy:

Thanks for the information on barrel threads. I reckon if the Martini could hold a cartridge that size then the Gibbs can as well. As for the chambering, I want something "proper" for the rifle and, if we go with a .45, it will be the .461 Gibbs.


I found the proof charge for the .577 listed in one of Winfer's books: an 800 grain cylindrical slug on top of 330 grains of black powder. Proof pressure between 9 and 10 tons. That would be one big bang!


Best to all,

Glenn

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belgmart
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Reged: 29/02/04
Posts: 78
Re: .577 2-3/4" barrel shank diameter [Re: Glenn_Fewless]
      #124558 - 20/01/09 05:19 AM

Glenn,

Would that be the #1 or the #2? Unless I am gravely mistaken, the basic case could still be the same...

Gert

--------------------
Martini's Rule!

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Glenn_Fewless
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Reged: 08/05/08
Posts: 103
Loc: Wisconsin, USA
Re: .577 2-3/4" barrel shank diameter [Re: belgmart]
      #124582 - 20/01/09 08:46 AM

Gert:

The .461 Gibbs #1 and #2 are the same except that the #2 has an even longer neck than the already long necked #1. All in all, neither are particularly attractive. Howsomever, most of the early Gibbs rifles were chambered for one of the two and I have not eliminated the possibility of chambering the rifle for one or the other.

Glenn

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belgmart
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Reged: 29/02/04
Posts: 78
Re: .577 2-3/4" barrel shank diameter [Re: Glenn_Fewless]
      #124681 - 21/01/09 05:22 AM

Glenn,

I can just imagine you shooting a Gibbs LR BP target rifle from the supine position, tang sight on the heel of the buttstock - if you want to, I can give you some drawings from contemporary sources... :-)

--------------------
Martini's Rule!

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Glenn_Fewless
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Reged: 08/05/08
Posts: 103
Loc: Wisconsin, USA
Re: .577 2-3/4" barrel shank diameter [Re: belgmart]
      #124695 - 21/01/09 07:52 AM

Gert:

Sorry dude, I have a whole stable full of target rifles. This one is going to be a sporter. Besides, if I were to build a Creedmoor rifle on a Brit action it would be one with a side lever. You don't happen to have a Westley Richards Model of '81 action that is going begging?

On the other hand, it would be cool to shoot long range with an original Farquharson actioned rifle, wouldn't it? And I do have another action I could make into a sporter... Trouble is, I would have to mortgage my house to get enough brass to shoot it as a competitive rifle.

Glenn

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belgmart
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Reged: 29/02/04
Posts: 78
Re: .577 2-3/4" barrel shank diameter [Re: Glenn_Fewless]
      #124799 - 22/01/09 04:56 AM

True, I do have to pay a steep price for my #2 Musket cases, unfortunately - but hey, if you want to be exclusive...
A deeley & Edge or a Fraser sidelever would be neat, even a Field (a bit more affordable too). Good thing is - for anything WR you could use #2 Musket, and yoo could use the long .50 case as basic brass. After all, you will need a custom reamer...
My 2nd Match rifle in #2 Musket is already shootable - Westley Richards ZAR Martini action, 1:16" Metford early style rifling in a 33 1/4" barrel. Metalwork is done, now for the wood and the finish...

--------------------
Martini's Rule!

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