barrel markings

[bigman]

Does 85o seem low ? just that most carts even clay loads are over that figure

[Al69ec]

850kg is the minimum proof I equates to 3 tons. Look On your cartridge boxes they normaly tell u if your guns suitable for use with that shell. It your responsibility to ensure your safe.

[bigman]

my gun says 850 BARS on the gamebore blue dia it has 70mm chamber length 900kgs per square cm so whats that relate to in BARS ?

 

it is confusing when some say kg others in bars

 

it seems that most 70mm chambers go to 3 1/4 tons where as mine is lower at 3 tons but it is 70mm chamber , god this gets confusing to me

Edited June 17, 2012 by bigman

[wymberley]

850kg is the minimum proof I equates to 3 tons. Look On your cartridge boxes they normaly tell u if your guns suitable for use with that shell. It your responsibility to ensure your safe.

 

 

But only because I know what you mean! Even though we have a contradiction in terminloogy, 850kg equates to 3 tons in the sense that for a serice pressure of 3 tons the proof pressure would have been 850kgs (5.5 tons). All figures ish.

 

850 is not necessarily low as the gun would have been proved to a figure consistant with the use for which the maker designed and made it for.

 

The problem is that guns tend to last a while and constant changes to the proof system makes life difficult - the biggest change for us was arguably going from having the proof markings annotated on the guns changed from the service pressure to the proof pressure.

[bigman]

whats the difference between proof and service preasure?

[wymberley]

my gun says 850 BARS on the gamebore blue dia it has 70mm chamber length 900kgs per square cm so whats that relate to in BARS ?

 

it is confusing when some say kg others in bars

 

it seems that most 70mm chambers go to 3 1/4 tons where as mine is lower at 3 tons but it is 70mm chamber , god this gets confusing to me

 

Hi, again, you weren't there when I started. Hopefully the proofing will now remain in bars for a while. I could well imagine tha your gun was made just prior to the change in proof regulations and had it been made a little later, it would have rated 900 but that's guesswork.

 

For all intents and purposes, you can read kgs for bar - Googling a pressures conversion table reflects little difference.

 

Edit: Service pressure is the maximum working pressure in different terminlogy and basically means the maximum pressure that any cartridge used should generate. Proof pressure is a higher pressure at which the gun is proved to ensure the gun is able to withstand that service pressure and then some.

Edited June 17, 2012 by wymberley

[bigman]

Hi, again, you weren't there when I started. Hopefully the proofing will now remain in bars for a while. I could well imagine tha your gun was made just prior to the change in proof regulations and had it been made a little later, it would have rated 900 but that's guesswork.

 

For all intents and purposes, you can read kgs for bar - Googling a pressures conversion table reflects little difference.

 

Edit: Service pressure is the maximum working pressure in different terminlogy and basically means the maximum pressure that any cartridge used should generate. Proof pressure is a higher pressure at which the gun is proved to ensure the gun is able to withstand that service pressure and then some.

getting clearer now , so my gun at 850bars that is the service preasure and would of been proofed to a higher preasure

[wymberley]

getting clearer now , so my gun at 850bars that is the service preasure and would of been proofed to a higher preasure

 

Now, this is where you ignore me and get professional advice. As we've already seen, a service pressure of 3 tons would have a proof pressure of some 51/2 equating to the 850kg figure. Now from the UK proof houses, the gun would previously have been stamped 3 tons as we did use the service pressure as an indicator. This has now changed in two ways; firstly we now use proof pressures and the terminology (via kg/cm2) is now bars (one bar is atmospheric pressure - 14.7psi in English).

 

Consequently, I believe that your 850 is proof pressure.

 

I don't have this problem, mine is proofed for 11/8oz - simples!

 

Be safe, be sure.

[Al69ec]

In the older British guns before the changes made to proof markings in the 1980's I am certain that the proof markings on the barrel flats such as 3 tons per square inch or 1 1/8 oz. referred to the service pressure or the max. usable load. The new markings for 2 1/2 inch chambers (and 2 3/4) is 850 bars and the old markings are acceptble as equivalent proof marks (provided the gun itself remains in proof). This would tend to indicate that 850 bar is a service pressure and one can use any cartridge that does not exceed this pressure. I am talking about a 12 ga. gun here.However on doing the conversion to PSI I find:

 

650bar = 9427 PSI

 

850 bar = 12328 PSI

 

Now SAAMI Max shotshell pressures are (in 12 ga.)

 

11500PSI = 793 bar

 

whereas the proof loads are: 19500 - 20500 PSI.

 

Is it safe to use a 12 gauge shot cartridge creating 650 bar (9427 PSI) pressure loaded with 32 grams of shot (1 1/8oz.) in a shotgun proofed in the London Proof House and proofmarked 3 tons per square inch, or marked 1 1/8 oz max. or marked 850 bars provided shell length and chamber length match and the gun itself is in proof?

Edited June 17, 2012 by Al69ec

[bigman]

Ok where would i find out for sure if its service or proof , its a shame i really like the blue diamonds seem to work really well thou the gun , anybody know of a good cart for 850 bar pigeon an clay loads ?

[wymberley]

Ok where would i find out for sure if its service or proof , its a shame i really like the blue diamonds seem to work really well thou the gun , anybody know of a good cart for 850 bar pigeon an clay loads ?

 

The Proof Houses themselves or the BASC is a good bet.

 

The latter some time ago sent me some info after I'd mislaid my references. It is an extract from a well work but unfortunately I'm not certain of the title so won't mention it.

 

This work indicates that where optional metric proof was stamped after 1984 it designated proof rather than service pressure (900 or 1200kg as required by the manufacturing design). After 1989 the proofing units changed to bar and the figures became 850 and 1200 but retained the proof and not service pressure.

 

I would imagine that if you have a cartridge which is safe to fire in a 3 ton service pressure chamber it will not exceed that pressure. The proof pressure for that chamber I would imagine would be somewhere over 5 tons. Also, that cartridge would perform satisfactorily. 850 bar is about 51/2 tons so it would make sense for that to be a proof pressure. Our satisfactorily performing cartridge pulls 3 tons which equates to 460 bar so a figure of 650 would appear to be out of order. Should this actually be required then surley it would be prudent to seek out a chamber proofed at 1200.

 

Be safe, be sure.

[sandy22]

would i be right in thinking that the proof steel means its proofed for steel shot

 

No, you wouldn't.

[deershooter]

if it says 1.8KG this could be the barrell weight they some times mark the weight now as if they were struck up on the outside the bores could be in proof but too thin

 

Deershooter

[bigman]

No, you wouldn't.

could you enlighten me please mate ?

[wymberley]

I'm avoiding steel shot like the plague so this is pure guesswork. Would suggest that Winchester Proof Steel has,in Winchester's view, some secret magical properties that makes it far superior to everyone elses' and makes missing difficult. In reality of course it's bog standard and not a Fleurs de Lis in sight.