Help understanding cartridge loads & barrel pressures

[Warcalf13]

I'm currently looking at buying a gun that has been magnumed from 3/4 choke out to 1/2 & 1/4. I've been informed it can take 12-76 & 1200k. 

 

My question being, what's the max capacity loads of either steel or bismuth/tungsten can I use through this?

For context, I'm wanting it as my primary fowling gun, so being able to tackle geese is quite important. Not fussed about being able to tackle canada's with it, but if there is a load through this that will cope it's a bonus. 

Thanks in advance.

[TIGHTCHOKE]

Welcome to Pigeon Watch.

[Dave at kelton]

Welcome.

12 speaks for itself

76 is chamber length in mm

1200 is the maximum pressure

cartridges have this information on the box so best go through with your local gunshop. Ask for wildfowling loads that equate to these parameters in whatever projectile material you prefer then pattern them.

[Warcalf13]

12 minutes ago, Dave at kelton said:

Welcome.

12 speaks for itself

76 is chamber length in mm

1200 is the maximum pressure

cartridges have this information on the box so best go through with your local gunshop. Ask for wildfowling loads that equate to these parameters in whatever projectile material you prefer then pattern them.

When you say 1200 is the max pressure for muzzle velocity? Because I've looked on the gamebore website and the only figure on their cartridges close to 1200 is the muzzle velocity. 

Sorry, as you can tell, this is all relatively new to me. Just don't want to buy a gun not fit for purpose.

Thanks

[Dave at kelton]

25 minutes ago, Warcalf13 said:

When you say 1200 is the max pressure for muzzle velocity? Because I've looked on the gamebore website and the only figure on their cartridges close to 1200 is the muzzle velocity. 

Sorry, as you can tell, this is all relatively new to me. Just don't want to buy a gun not fit for purpose.

Thanks

Maximum Pressure. I don’t think you will find any U.K. cartridges approaching this pressure due to CIP rules although others may tell me I am wrong. Best speak to your gunshop so they can explain it all to you as you are going to be using 3” magnum cartridges. If they are selling you the gun they have an obligation to make sure you understand what you are buying if they are any good.

[eggy74]

1200 bar is the higher rated pressure, so you should be able to shoot anything through it (850 bar is the lower standard)

[wymberley]

38 minutes ago, Warcalf13 said:

When you say 1200 is the max pressure for muzzle velocity? Because I've looked on the gamebore website and the only figure on their cartridges close to 1200 is the muzzle velocity. 

Sorry, as you can tell, this is all relatively new to me. Just don't want to buy a gun not fit for purpose.

Thanks

Sorry to say it but your ice is thin and melting fast. You need to have a chat with whoever is selling this gun and ask him to clarify what he's talking about. Altering choke has nothing to do with 'magnuming' unless it means that the chokes were altered and  other alterations which became necessary if the chambers were altered from, say, 70mm (2&3/4") up to the 76mm. Can't imagine what 1200k is, other than the older kg/sqcms. Let's assume that it's Bar or MPA and if so that pressure has nothing to do with you - as the end user - but is solely in the domain of the proof house. It might be an idea to seek the advice from someone who can eyeball the gun's proof marks and who understands what they're telling him. and who can check the barrels' internal dimensions.

Me? I'd walk away. There's loads of guns out there which are unadulterated and which will meet your needs 'off the shelf'.

[JohnfromUK]

5 minutes ago, wymberley said:

Can't imagine what 1200k is, other than the older kg/sqcms.

That is just what it is.  I have an AyA with 2 sets of barrels; the 'standard' 28" proofed at 850Kg, and a set of 'magnum' 30" proofed at 1200Kg, both 70mm case.   The 'magnum' barrels have ridiculously tight ckokes.

[wymberley]

5 minutes ago, JohnfromUK said:

That is just what it is.  I have an AyA with 2 sets of barrels; the 'standard' 28" proofed at 850Kg, and a set of 'magnum' 30" proofed at 1200Kg, both 70mm case.   The 'magnum' barrels have ridiculously tight ckokes.

This reply is iffy - it's chucking it down here which means my internet is intermittent at best.

This gun could be Italian which as Kg is a weight it could be the weight of the barrels.

[Smudger687]

1 hour ago, Warcalf13 said:

I'm currently looking at buying a gun that has been magnumed from 3/4 choke out to 1/2 & 1/4. I've been informed it can take 12-76 & 1200k. 

 

My question being, what's the max capacity loads of either steel or bismuth/tungsten can I use through this?

For context, I'm wanting it as my primary fowling gun, so being able to tackle geese is quite important. Not fussed about being able to tackle canada's with it, but if there is a load through this that will cope it's a bonus. 

Thanks in advance.

Payload is not the primary concern when it comes to pressures etc. 1200 bar pressure proofing is far beyond any commercial ammunition you'll ever be able to find for it, and most guns can take much more pressure than the proof pressure without damage. 

If you're talking about how much payload you'll be able to get into a 3 inch shell, then typically its around 36g for steel and 42g for bismuth. You can fit upwards of 56g of 18g/cm3 tungsten into a 3 inch shell but it's wasteful and unnecessary, most people loading tungsten tend to keep it to 28g or less through smaller bore shotguns. 

What I and many others have found, however, is that steel and other non-tox responds quite well to tighter than half choking, so tying yourself down with a fixed choke gun may not be the ideal option. Bismuth will more than likely need more than half choke for ranges beyond 35 yards anyway if that's a consideration for you. 

Besides that, put anything through it. 

[old'un]

13 minutes ago, wymberley said:

This reply is iffy - it's chucking it down here which means my internet is intermittent at best.

This gun could be Italian which as Kg is a weight it could be the weight of the barrels.

1200Kg barrels?

[JohnfromUK]

23 minutes ago, wymberley said:

This reply is iffy - it's chucking it down here which means my internet is intermittent at best.

This gun could be Italian which as Kg is a weight it could be the weight of the barrels.

No, it's not 'iffy'.  1200 Kg is a proof value (higher proof) used with 70mm chambers in the UK.  Attached is a photo of the proof marks, proofed at 850 and reproofed at 1200.  Note that 1 BAR is (virtually) 1 Kg/sq cm.  1200 is a 'standard' value for higher proof.

Various countries print the barrel weight and for the Spanish proof this is printed (example) 1280 g.  (Note NOT Kg, where it would be 1.280 Kg)

Edited December 30, 2023 by JohnfromUK
Forgot to add photo!

[TIGHTCHOKE]

1 minute ago, old'un said:

1200Kg barrels?

Negligible felt recoil.............

[wymberley]

7 minutes ago, old'un said:

1200Kg barrels?

More often than not there's no sign of the comma.

[wymberley]

6 minutes ago, JohnfromUK said:

No, it's not 'iffy'.  1200 Kg is a proof value (higher proof) used with 70mm chambers in the UK.  Attached is a photo of the proof marks, proofed at 850 and reproofed at 1200.  Note that 1 BAR is (virtually) 1 Kg/sq cm.  1200 is a 'standard' value for higher proof.

Various countries print the barrel weight and for the Spanish proof this is printed (example) 1280 g.  (Note NOT Kg, where it would be 1.280 Kg)

Yes it is. It's taking several attempts and up to 10 minutes before the internet decides to play before I can post and I lose it again

[JohnfromUK]

I'm sorry, I thought you meant my post was 'iffy', which I don't believe it is.  My gun was presumably what is referred to as 'magnumed' by having it proved to take 1200 Bar when the original barrels are 850 Bar.  This was done by a previous owner who added the 30" full and extra full 'superior' proofed barrels to supplement the 28" original barrels (which are still at 850 Bar and Spanish marks).  The action has both the original Spanish marks and the Birmingham marks where the second set of barrels were added in Birmingham.

You are right that some foreign proof houses stamp tghe barrel weight and 1200g would not be a mile out for many - BUT I have only ever seen this in grammes (g).

[Warcalf13]

51 minutes ago, wymberley said:

This reply is iffy - it's chucking it down here which means my internet is intermittent at best.

This gun could be Italian which as Kg is a weight it could be the weight of the barrels.

The gun in question for me is an AYA, which has been bored out from 3/4, to one barrel at 1/2 and another at 1/4. Like I stated before, it's 12-76, so obviously can handle 76mm cartridges. The gun was bored out in the UK by ASI gunsmiths, so I'm confident it's not a foreign bodge job. All I want to know, is what loads it would be able to take and would that do for geese. 

 

If 1200 bar is suitable for commercial ammo, sounds like I'll be fine 

[Smudger687]

Just now, Warcalf13 said:

The gun in question for me is an AYA, which has been bored out from 3/4, to one barrel at 1/2 and another at 1/4. Like I stated before, it's 12-76, so obviously can handle 76mm cartridges. The gun was bored out in the UK by ASI gunsmiths, so I'm confident it's not a foreign bodge job. All I want to know, is what loads it would be able to take and would that do for geese. 

 

If 1200 bar is suitable for commercial ammo, sounds like I'll be fine 

You can take any factory cartridge with an unfolded case length of 3 inches or less, or any homeloaded shell with an unfolded case length of 3 inches or less and an average maximum chamber pressure less than the proof pressure.

I suspect you won't be homeloading, so you'll be looking at UK factory offerings. In my opinion, bismuth offerings are OK but the shot size maxes out at 4's so is a little too small for geese, and tungsten isn't loaded commercially. That leaves steel. My preference as a do-all cartridge is a 3 inch load of 2's. You'll still need to go for headshots on Canadas unless they're really close, but you'd have to do that with any 3 inch steel load anyway. 

[JohnfromUK]

1 minute ago, Warcalf13 said:

The gun in question for me is an AYA, which has been bored out from 3/4, to one barrel at 1/2 and another at 1/4. Like I stated before, it's 12-76, so obviously can handle 76mm cartridges. The gun was bored out in the UK by ASI gunsmiths, so I'm confident it's not a foreign bodge job. All I want to know, is what loads it would be able to take and would that do for geese. 

 

If 1200 bar is suitable for commercial ammo, sounds like I'll be fine 

I have not used heavy loads, so can't directly answer your question but 76 mm is the old 3" and 1200 Bar is the proof normally carried out on chambers longer than 70 mm.  (1200 is optional 'superior' for 70 mm chambers).  So - use a CIP approved cartridge (basically all sold in the UK) suitable for 3" or 76 mm chambers.  Most cartridges have the details of suitability on the box.  As to what brand/type - that would be up to you.  If you use HP steel (as many do and are needed in some circumstances) you may wish to consider a 'steel proof' with the 'fleur de lis' mark for steel.

[wymberley]

1 hour ago, JohnfromUK said:

I'm sorry, I thought you meant my post was 'iffy', which I don't believe it is.  My gun was presumably what is referred to as 'magnumed' by having it proved to take 1200 Bar when the original barrels are 850 Bar.  This was done by a previous owner who added the 30" full and extra full 'superior' proofed barrels to supplement the 28" original barrels (which are still at 850 Bar and Spanish marks).  The action has both the original Spanish marks and the Birmingham marks where the second set of barrels were added in Birmingham.

You are right that some foreign proof houses stamp tghe barrel weight and 1200g would not be a mile out for many - BUT I have only ever seen this in grammes (g).

Italians have done it in Kgs. A search on here will reveal that this is so and even though it's Kgs and not Kg/sqcm the posts reflect some confusion - not helped by the fact that the decimal point - usually a comma - is either not there or 'unreadable'.

[Fil]

2 hours ago, wymberley said:

Italians have done it in Kgs. A search on here will reveal that this is so and even though it's Kgs and not Kg/sqcm the posts reflect some confusion - not helped by the fact that the decimal point - usually a comma - is either not there or 'unreadable'.

Just for information, Spanish put barrel weight (at time of proof) in gmos. Different from 1200kgs or kp/cm2 or bar. It can be confusing.

[Fellside]

I think the most sensible suggestion above is - walk away. If it’s been ‘worked on’ then an experienced gun smith would have to inspect and rubber stamp so to speak. Please don’t take this the wrong way but you don’t have the experience/knowledge to assess for safety yourself. 

There are so many decent inexpensive semi-autos out there, steel proofed, multi chokes and 3” chambered - all the bells and whistles. Some also have shims for fitting. You can often try out one or two used ones at shooting grounds….just a thought….?

[GingerCat]

16 minutes ago, Fellside said:

I think the most sensible suggestion above is - walk away. If it’s been ‘worked on’ then an experienced gun smith would have to inspect and rubber stamp so to speak. Please don’t take this the wrong way but you don’t have the experience/knowledge to assess for safety yourself. 

There are so many decent inexpensive semi-autos out there, steel proofed, multi chokes and 3” chambered - all the bells and whistles. Some also have shims for fitting. You can often try out one or two used ones at shooting grounds….just a thought….?

This. Find something  proofed for  steel shot and 3in Chambers. You then know for a fact it can take anything commercially on sale in that cartridge size and I'm pretty sure lots of geese have been dropped with steel from similar.   Multi choke preferably, any style you like from sbs/ou/semi/pump/single shot as long as it fits. Buyers market at present. 

[Fil]

45 minutes ago, GingerCat said:

This. Find something  proofed for  steel shot and 3in Chambers. You then know for a fact it can take anything commercially on sale in that cartridge size and I'm pretty sure lots of geese have been dropped with steel from similar.   Multi choke preferably, any style you like from sbs/ou/semi/pump/single shot as long as it fits. Buyers market at present. 

That's why all guns now are being built 3" steel shot proofed. To negate user error. A manufacturer can produce a 12 bore gun knowing that a user can put any cartridge though it that is available on the market knowing their gun is proofed for anything.  Obvs there is the 3 1/2" but most doubles are 3". It's called **** covering. Most of my old customers haven't a clue what make their guns are let alone chamber depth. 

[London Best]

8 hours ago, Fil said:

That's why all guns now are being built 3" steel shot proofed. To negate user error. A manufacturer can produce a 12 bore gun knowing that a user can put any cartridge though it that is available on the market knowing their gun is proofed for anything.  It's called **** covering.

The Americans have been doing this since forever.

But their guns are horrible!