Handloading .455 for Webley MK I

olivierlamothe said:
Are you sure about the max pressure of webley mk1 ? Realy 16 000 psi ?
Click to expand...

well lets go back to the 6 long tons or 13,500 psi , which is what is stamped on the revolver .

this is a pressure measurement between the case head and the firearm and a measurement of rearward thrust .

so at the very least your good to 13,500 psi .

but how much pressure needs to be generated within the case itself to create 13,500 psi of rearward thrust ?
remember the case wall will grip the chamber , and the higher the pressure the more the case will grip the walls .
the pressure would have to be a lot higher than 13,500 within the case .


the other thing to consider is how many of these where rechambered to 45acp , , and then have had +p jacketed ammo fired through them . there has to be tens of thousands of these conversions out there , but I have only seen one set of pictures online of a blown up webley .

the first thing I'd measure on a 45acp conversion is the chamber throat in the cylinder , and then open them up to at least .452 .
a lot of them are tight , which ends up swagging down the bullet and creating a pressure spike .
by opening up the throat your allowing the bullet to move forward without creating a pressure spike ,the next area which will offer resistance to the bullet is where it enters the barrel , but by then the bullet has momentum and it is also starting to bleed pressure through the cylinder gap .
 
found a few bits here ....

http://www.rathcoombe.net/sci-tech/classics/webley/webley-mk-vi.html

" Load Development

The Commission Internationale Permanente pour l'Epreuve des Armes 'a Feu Portatives (CIP) rates the .455 Webley Mark II cartridge with a maximum average pressure (MAP) of 900 bar, which is 13,050 psi. At face value, this compares well to the marking stamped on the barrel of my pistol that indicates 6 tons per square inch, or (nominally) 13,440 psi. However, this 6 tons psi is actually copper units of pressure or CUP, not true psi as with the CIP value. Furthermore, it is probably base or axial copper crusher measurement per British Proof House practice, as opposed to radial or side measurement. Using the conversion of British Proof House tons per square inch in true pressure (derived from CIP data) gives 1050 bars and 15,230 psi for 6 tons psi. Since 1050 bars is squarely between the CIP rating for the .45 Colt and .45 Smith & Wesson Schofield, and consistent with SAAMI specs, I feel confident this is still a safe upper limit"


the next one is in german , but if I understand it correctly the first part is a measurement of rearward thrust ( axial thrust ) ( 13,053 psi) the second measurement is the conversion of axial thrust to radial thrust . ( 15,011 psi ) and the third one is actual pressure measured by piezoelectric sensor ( 16,969 psi )

this is the same round with 3 different ways to express the pressure produced within the cylinder .


http://www.lhs-germany.de/uploads/media/455_Webley_Mk_II.pdf

when talking about pressure a person has to pay careful attention to how they are doing it and what scale they are doing it in .
 
burnt_servo said:
well lets go back to the 6 long tons or 13,500 psi , which is what is stamped on the revolver .

this is a pressure measurement between the case head and the firearm and a measurement of rearward thrust .

so at the very least your good to 13,500 psi .

but how much pressure needs to be generated within the case itself to create 13,500 psi of rearward thrust ?
remember the case wall will grip the chamber , and the higher the pressure the more the case will grip the walls .
the pressure would have to be a lot higher than 13,500 within the case .


the other thing to consider is how many of these where rechambered to 45acp , , and then have had +p jacketed ammo fired through them . there has to be tens of thousands of these conversions out there , but I have only seen one set of pictures online of a blown up webley .

the first thing I'd measure on a 45acp conversion is the chamber throat in the cylinder , and then open them up to at least .452 .
a lot of them are tight , which ends up swagging down the bullet and creating a pressure spike .
by opening up the throat your allowing the bullet to move forward without creating a pressure spike ,the next area which will offer resistance to the bullet is where it enters the barrel , but by then the bullet has momentum and it is also starting to bleed pressure through the cylinder gap .
Click to expand...

Ok, ok i get it but it's still complicated to me. By reading on that a little bit more i should understand better what realy is 13 500 psi in my mk1.

On the other hand, my cylinder troath is .450 i shoot .452 200gr swc should does trimming the chambers will change something ?

Thanks !
 
olivierlamothe said:
Ok, ok i get it but it's still complicated to me. By reading on that a little bit more i should understand better what realy is 13 500 psi in my mk1.

On the other hand, my cylinder troath is .450 i shoot .452 200gr swc should does trimming the chambers will change something ?

Thanks !
Click to expand...

if it was my gun , I'd open the throat to at least .452 .

when you say trimming , are you meaning opening up the throats , or something else?
 
HeadDamage said:
So the wolf round nose lead loads are safe in a MK VI?
Click to expand...

- And a Mk. VI is a much stronger pistol than is a Mk I - the metallurgy improved throughout the Webley's production, and each Mark was stronger than the one before it. I definitely would steer to the mild side for a Mk I, and I doubt I'd risk 500 fps from a 4-inch barrel.

You might consider reloading with black powder for a Mk I.
 
So back to the good old thread ))
Moved to a new place and have a better reloading banch in my garage.

The good news is Starline is making Webley MK2 brass.
Loaded a few rounds with 3gr of Trail Boss behind 265gr hollow base round nose Jet's bullets.
(Will post pictures later)
 
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