I just read the No. 22 edition of the Hatari Times by Harald Wolf. He writes a very interesting history and analysis of the various .416 calibers with an emphasis on the .416 Rigby. He explains the chamber pressure issue that dogs the Rigby and Rem. Mag. in a very understandable way.

I do not know him, but I like is magazine and his style. He does not mince words and tells things as he sees them.
Maybe Nickudu could put the article in his forum for all to see.

Hi Dogcat! While I'd certainly like to borrow #22 for scanning, I think it far too soon to post from it and I think Harald would agree. Harald Wolf has always been very good to us here at "AR" (even while offering back-issues for sale). Please, let me know about the possibility of scanning the issue? Thanks!

P.S. - While we're on the subject: Hatari-Times Issues #1, #2, #3, #5, #13, #14, #15, #17 - #22 all needed for scanning. Will return loaned magazines asap. Thanks for your help!

Hmmmm.... still don't have my copy of the latest yet!

Dogcat,

What pressure issues did Harald report with the 416 Rigby? I'm familiar with some pressure problems early on with the Remington, but I've never heard of pressure problems with the Rigby. In fact, the big Rigby cartridge has always been thought of as a very moderate pressure cartridge. I've played with several different rifles in the Rigby chambering over the years, and none have given the slightest indication of pressure problems. I would be interested to learn what Harald is talking about.

Many thanks,

Tom

Ditto.

I am taking the following from Harald's article on page 32 -

Quite a few amateurs believe that the .416 Rigby, due to its rather low chamber pressure, would stress the bolting system of a given rifle far less than other similar cartridges. I am afraid to tell you that this is not true! According to CIP standards (usually consderably tighter than American SAAMI standards) the maximum chamber pressures (copper crushing method) are as follows -
.416 Rigby= 2850 BAR, .404 Jeff/.425 WR = 3200 bar, 11.2x72 Schuler= 3300 bar, .416 Rem mag. = 3800 bar. The .416 Rigby having clearly the lowest chamaber pressure of the lot. The actual strain exerted on the bolting lugs and the action receiver is NOT the chamber pressure, but the product of the chamber pressure multiplied by the cross section of the cartridge base. That sounds complicated, but I will explain: The larger the cartride base combined with a given pressure - the higher the strain on the action. The .416 Rigby has a low chamber pressure but a very large basic case diameter while the figures of the .416 Rem Mag are just the reverse. At the end of the day, despite a considerable difference in chamber pressures, both calibers deliver the same amount of tensile stress to the rifle action."

It is a fairly long article and is interesting. I am not sure what I know now, but this makes me less worried about the .416 Rem Mag.

quote:

Originally posted by dogcat:
I am taking the following from Harald's article on page 32 -

Quite a few amateurs believe that the .416 Rigby, due to its rather low chamber pressure, would stress the bolting system of a given rifle far less than other similar cartridges. I am afraid to tell you that this is not true! According to CIP standards (usually consderably tighter than American SAAMI standards) the maximum chamber pressures (copper crushing method) are as follows -
.416 Rigby= 2850 BAR, .404 Jeff/.425 WR = 3200 bar, 11.2x72 Schuler= 3300 bar, .416 Rem mag. = 3800 bar. The .416 Rigby having clearly the lowest chamaber pressure of the lot. The actual strain exerted on the bolting lugs and the action receiver is NOT the chamber pressure, but the product of the chamber pressure multiplied by the cross section of the cartridge base. That sounds complicated, but I will explain: The larger the cartride base combined with a given pressure - the higher the strain on the action. The .416 Rigby has a low chamber pressure but a very large basic case diameter while the figures of the .416 Rem Mag are just the reverse. At the end of the day, despite a considerable difference in chamber pressures, both calibers deliver the same amount of tensile stress to the rifle action."

It is a fairly long article and is interesting. I am not sure what I know now, but this makes me less worried about the .416 Rem Mag.

Dogcat, is it the tensile stress that should worry a hunter, or the difficulty in cartridge extraction? As I understand it, it's the sticky extraction of a high pressure cartridge that potentially puts the hunter in danger, not the comparatively equivalent tensile stress numbers.

He talks a little bit in the article about extraction problems but attributes that to ambient temperature. Here is what he says -

"However, smokeless gun powders are chemcial products, which are prone to alter their combustion characteristics if exposed to heat, and the British Cordite, a strange noodle-shaped propellant, was very sensitive to tropical heat, indeed. A cartridge with a rather low maiximum chamber pressure rects rather forgiving to reasonable ove-heating, whil a high-pressure cartridge might react with dangerously high pressure peaks, thus causing sticky or even impossbile extraction of the empty shell. Therefore, the British cartridge designers had to keep the chamber pressure on the lower end. The Germans, who used high-energy flake powder, which were connsiderably superior to the Cordite, could safely use higher chamber pressures in smaller cartidge cases. With modern powders a chamber pressure of 3200 bars is always much safer and less heat sensitive than a cartidge developing a chamber pressure of 3800 bars. Anyway, rifle ammunition should never get exposed to excessive heat and direct sunlight, as sticky extraction might be extremely dangerous. Once overheated, you unfortunately cannot reverse the alteration of the poweder by cooling down the shells. "

He later mentions that he likes the lower chamber pressures for accuracy reasons stating that the .404 Jeff is more accurate for him than the other .416's. He says he cannot verify this scientifically, but his experience has shown him this.

Everyone, please understand that I am not a gun expert nor a technical expert on ballistics. I am merely repeating with I saw in Hatari Times.

Here are the latest CIP pressure standards, as of May 15, 2002 revision, some differences from those listed above:

Maximum average chamber pressure specified:

.416 Remington ....... 4300 BAR = 62,350 psi
.416 Rigby ........... 3250 BAR = 47,125 psi
404 Rimless NE ....... 3650 BAR = 52,925 psi
.505 Gibbs ........... 2700 BAR = 39,150 psi
500 Jeff&Schuler ..... 3300 BAR = 47,850 psi

Bolt thrust: would be proportional to the product of pressure and the cross-sectional area of the internal base of the cartridge, assuming other factors equal.

This is not at all a concern for modern actions sized to fit the cartridge up to and including .416 Rigby head size, however this does not include standard Mauser 98's opened to .416 Rigby length: That is where the bolt thrust might become an issue due to locking lug recess undercutting.

Even the makers of the CZ 550 Magnum-actioned .505 Gibbs stamp that barreled action pressure limit at 3800 BAR = 55,100 psi.

.416 Rigby brass failure will be the deciding pressure issue in a true magnum action.

The .505 Gibbs may be marginal. But what safety factor is built into the actions?

The .416 Rigby has way more body taper than the .404 Jeffery, .416 Remington, 500 Jeffery and 500 Schuler: that means it will never be an extraction problem whatever the pressure.

Did Harald Wolf think the case body taper was an issue with bolt thrust?

quote:

Originally posted by bwanamrm:
Hmmmm.... still don't have my copy of the latest yet!

Nor I. In fact, I have a bone to pick with him over back issues.

quote:

Nor I. In fact, I have a bone to pick with him over back issues.

I have an issue over issues, period. I've spent $125 for a renewal for a three year subscription to a "quarterly" magazine and received exactly three copies in two years!

Take my word for it... if you don't already subscribe... save your money!

Same with me, but he did not publish during that time. He was not able to make a couple of trips he was planning. He is a gunmaker first and a publisher second. When he does publish, it is good stuff.

Be patient, its coming soon...all about Australia and Big Buff...I've been proofing till we hours of the AM last few nights!!
Harald is an honorable gentleman, and consummate hunter...takes time like fine wine, and no focus on the record book!! Y'all will get the issues you subscribed for..I'll betcha...

All this chamber pressure thing is a joke IMO..The way you get pressure in ANY round is to simply put too much powder in it!~

I have never had any pressure problems in either .416 round,nor in the .375 H&H, and the African heat thing is another joke, like its hotter their than in the USA? BS have you ever been to West Texas, Arizona, So. California, it will give bloody ole Africa a run for the money, except nobody has pressure problems in those states...

I have loaded my 416 Rem, and Rigbys to 2400 FPS without issure, and I get that velocity with two grains under book max btw...

Interesting, I took some 375 H&H Federal Safari Premium, 300 gr Trophy Bonded-High Energy rounds to Mozambique this year...had one stick in the chamber in a beautiful PH provided custom Musgrave rifle shooting my second croc...not fun...in looking back at all of the rounds we had fired, the primers were flatened big time, in every round...pressure, or maybe a dusty/sandy chamber?? don't know...we incidentally did NOT clean the chamber and I shot my nice Bushbuck later ...no problem...but it was 105 in the shade when I shot the croc, sunset, maybe 90 when I shot the Bushbuck??....

I'm with Atkinson. I live in Utah and shoot a 416 in temperatures over a 100 degrees in the summer without any pressure problems. Loading swift 400 grain bullets to just within a couple of grains of max with 24oo fps velocities. I believe this is a dog that has been beaten too often and for nothing.