Smokeless Loads in Mark 1 Webley .455 cal

[cyclone]

I just came across this passage , and was wondering how much of it "makes sense" ?.....

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. I believe the 900 bar MAP imposed by the CIP was made in deference to the older blackpowder revolvers.

The .45 Auto Rim is rated by CIP to 1200 bar, or 17,400 psi, while the standard .45 Auto Colt rates 1300 bar, or 18,850 psi. However, US manufactured .45 ACP ammunition is typically loaded to a much higher level than this; SAAMI permits 21,000 psi for standard loads and 23,000 psi for +P loads. What this means is that if standard .45 ACP loads are fired in a Webley Mk VI revolver they greatly exceed the proof test pressures, being 38% over the MAP, and are potentially dangerous. Most unreformed .45 ACP users in the Webley Mk VI note that a "steady diet" of such loads will "loosen things up". Read that as "will produce yielding in the metal of the cylinder and frame with every shot fired". Steel can be a very forgiving material, but not always. In some cases, the cylinders have been catastrophically destroyed, with injuries to the shooter.

 

[Ardent]

A note on Trail Boss, it's a great antique powder if you're not looking for much velocity, and it needs a very heavy crimp to perform best. I loaded it in .455 Colt/Eley and am presently loading it in .41 Colt, neither showed promise until heavy roll crimps were applied, then they compete for the best load/powder. As a general rule of thumb, I find for antiques you wouldn't want to push a bullet past 750fps over trailboss, as velocities climb its pressure rises drastically and very sharply pressure curve wise. In fact in a BP Webley I'd be limiting that to 600, 650 max or so.

 

[Ardent]

I just came across this passage , and was wondering how much of it "makes sense" ?.....

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. I believe the 900 bar MAP imposed by the CIP was made in deference to the older blackpowder revolvers.

The .45 Auto Rim is rated by CIP to 1200 bar, or 17,400 psi, while the standard .45 Auto Colt rates 1300 bar, or 18,850 psi. However, US manufactured .45 ACP ammunition is typically loaded to a much higher level than this; SAAMI permits 21,000 psi for standard loads and 23,000 psi for +P loads. What this means is that if standard .45 ACP loads are fired in a Webley Mk VI revolver they greatly exceed the proof test pressures, being 38% over the MAP, and are potentially dangerous. Most unreformed .45 ACP users in the Webley Mk VI note that a "steady diet" of such loads will "loosen things up". Read that as "will produce yielding in the metal of the cylinder and frame with every shot fired". Steel can be a very forgiving material, but not always. In some cases, the cylinders have been catastrophically destroyed, with injuries to the shooter.

You're info is very correct on the .45 ACP/Auto Rim in Webleys. There is not an antique Webley made that's proof loads were even anywhere near the pressures standard .45 ACP produces. The converted Webleys were done so with zero thought given to safety or suitability, it was merely a way to make them more appealing to folks who don't know what ".455" is. It's a dangerous thing, and never buy a .45 ACP converted antique Webley as you can be assured it's fired standard .45 ACP in the past. GrantR has an excellent post on the British Militaria Forums complete with blow up pics of what can happen with .45 ACP, it may have been posted here too I know I've quoted it. The fact so many have "gotten away with it" shooting .45 ACP in conversions is only a testament to the Webley, it does not mean it's safe, in fact it's incredibly dangerous.

 

[jethunter]

I just came across this passage , and was wondering how much of it "makes sense" ?.....

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. I believe the 900 bar MAP imposed by the CIP was made in deference to the older blackpowder revolvers.

The .45 Auto Rim is rated by CIP to 1200 bar, or 17,400 psi, while the standard .45 Auto Colt rates 1300 bar, or 18,850 psi. However, US manufactured .45 ACP ammunition is typically loaded to a much higher level than this; SAAMI permits 21,000 psi for standard loads and 23,000 psi for +P loads. What this means is that if standard .45 ACP loads are fired in a Webley Mk VI revolver they greatly exceed the proof test pressures, being 38% over the MAP, and are potentially dangerous. Most unreformed .45 ACP users in the Webley Mk VI note that a "steady diet" of such loads will "loosen things up". Read that as "will produce yielding in the metal of the cylinder and frame with every shot fired". Steel can be a very forgiving material, but not always. In some cases, the cylinders have been catastrophically destroyed, with injuries to the shooter.

I think 12K-13K psi is a reasonable limit on these old revolvers, but it is hard to generalize because there is such a wide variation in condition. Condition varies from "like new" to "not safe to fire". Judging a suitable load depends on condition as much or more than design and metallurgy limitations when looking at 120 year old military surplus firearms. Making a blanket statement that such-and-such a model is suitable for ### amount of pressure is worthless and maybe even dangerous. Condition is everything.

PERSONALLY - I set my limit at 12K-13K psi for a strong condition MKI/MKII. Using 250-260 gr bullets, that's about 5.0 gr Unique in 45acp/45autorim brass; and 4.2 gr Unique in .455 MKII brass.

A lot of the MKI/II revolvers have very tight throats. That increases pressure beyond what we expect right at the time that it is most dangerous - when the bullet is still in the cylinder and pressure is still rising in the sharp part of the pressure curve. That's ONE of the reasons that it is good practise to use soft cast bullets in these revolvers. The other 2 reasons to use soft bullets are to prolong barrel life, and to improve accuracy, both of which are very applicable to the webley MKI/II/III service revolvers.

I have seen enough "shot loose" .45acp-converted MKI/II revolvers to say that full-power .45acp is too much for them as a steady diet. OTOH, people are welcome to load hotter if they choose and I don't give a poop. It's their money, their gun, and their problem if something goes wrong. Load it with 50 caliber BMG for all I care.