AYA Proofing

[harkom]

IIRC Birmingham Proof House lost the plot a bit - around the time that they felt the need to "align" British proof with the edicts from Europe ie CIP regs.

You would/might get an answer to your query if you contact the Proof House direct.

[wymberley]

17 minutes ago, enfieldspares said:

Curiouser and curiouser. There were a few AYA guns that had an odd length chamber that wasn't 3" but slightly longer. As there was a now obscure 12 bore cartridge of somewhat over three inches. One went through Holt's maybe three, four or five years ago. It is odd that the cartouche seems to be 12-76.8? Or somesuch? In which case this may be of those guns yet, from recollection they were marked as 77mm? or 78mm? A trawl through Holt's back catalogues anyway will eventually find it after some effort.

Yep. I can only assume that if this is a No3 3" Magnum, then the "magnum" in amongst the proof marks must relate to the model name. This as both barrel flats already reflect supplementary or magnum marks - although as has been said one would have expected 1200 'whatevers' in that case in view of the '76'. A case of the midnight oil for you, perhaps.

[K.K.B]

1 hour ago, enfieldspares said:

Curiouser and curiouser. There were a few AYA guns that had an odd length chamber that wasn't 3" but slightly longer. As there was a now obscure 12 bore cartridge of somewhat over three inches. One went through Holt's maybe three, four or five years ago. It is odd that the cartouche seems to be 12-76.8? Or somesuch? In which case this may be of those guns yet, from recollection they were marked as 77mm? or 78mm? A trawl through Holt's back catalogues anyway will eventually find it after some effort.

I have a folding .410 with 76mm chambers

58 minutes ago, harkom said:

IIRC Birmingham Proof House lost the plot a bit - around the time that they felt the need to "align" British proof with the edicts from Europe ie CIP regs.

You would/might get an answer to your query if you contact the Proof House direct.

That's a good idea, I had contacted Gamebore in hope of a reply, but still waiting. I'll contact one of the proof houses to get some confirmation.

[grahamch]

19 hours ago, K.K.B said:

Here is a pic of my barrels as requested above

Ok, cheers for that. I will contact them and see what they say about it. 

old english 3 inch guns used to be proved at 3.5 tons psi for 1.5 ounces of shot up until l think the 1950s. 

with modern powders this went to 4 tons psi for loads to 1&7/8 ounces. 

 

[K.K.B]

7 hours ago, grahamch said:

old english 3 inch guns used to be proved at 3.5 tons psi for 1.5 ounces of shot up until l think the 1950s. 

with modern powders this went to 4 tons psi for loads to 1&7/8 ounces. 

 

Do you think the gun was stamped wrong then?

[Guest cookoff013]

On 09/07/2021 at 19:37, wymberley said:

Yep. I can only assume that if this is a No3 3" Magnum, then the "magnum" in amongst the proof marks must relate to the model name. This as both barrel flats already reflect supplementary or magnum marks - although as has been said one would have expected 1200 'whatevers' in that case in view of the '76'. A case of the midnight oil for you, perhaps.

All chambers are made longer than published. To have a stamp saying 76mm must have 76+2mm i think. Its in the cip chamber spec.

[Gerry78]

On 08/07/2021 at 19:25, K.K.B said:

Hi all, It's about time I made my first post, I've been reading this forum for years. Anyway I picked up an AYA No.3 3" Magnum the other day in excellent condition, serial number and code date it to 1964, but I'm noticed that on the barrel flats it appears to be proofed to 900kg. What constitutes a "Magnum gun"? I thought the majority of these were proofed to 1200kg. Also being a 3" chamber, does that mean I can put any 3" commercial cartridges through it without any worry?

Cheers

 

 

My aya no3 magnum made 1978 proofed at 1200kg 3 inch chamber you should be good to put any standard steel through it I know you posted regarding magnum loads but as London best says very rarely you need 3 inch cartridges I take it you’ve emailed aya they should keep u right 

[JohnfromUK]

Seeing this thread 'revive' reminded me that I did a further investigation into my gun with the  'odd' proof combination of 1200 Kg and 70mm chambers.  (see previous page post of 9th July where there is a photo of the proof marks). 

I measured the chambers using a plug gauge.  A 'normal' AyA proofed for 70 mm shows the plug gauge drops in to slightly over 2 3/4"  (my gauge is Imperial).  The 1200 Kg proof barrels, my gauge drops in to near dead on the 3" marker (i.e about 7/32" longer chambers). 

A hypothesis might be that these were intended to be 3", but were just too short for the proof house to accept that the chamber was 76 mm (using their formal 'standard plug gauge").  The barrels were made by AyA (in Spain) as an additional pair some years after the gun was made, but it is my understanding that they were fitted and proofed in the UK.

[London Best]

4 minutes ago, JohnfromUK said:

Seeing this thread 'revive' reminded me that I did a further investigation into my gun with the  'odd' proof combination of 1200 Kg and 70mm chambers.  (see previous page post of 9th July where there is a photo of the proof marks). 

I measured the chambers using a plug gauge.  A 'normal' AyA proofed for 70 mm shows the plug gauge drops in to slightly over 2 3/4"  (my gauge is Imperial).  The 1200 Kg proof barrels, my gauge drops in to near dead on the 3" marker (i.e about 7/32" longer chambers). 

A hypothesis might be that these were intended to be 3", but were just too short for the proof house to accept that the chamber was 76 mm (using their formal 'standard plug gauge").  The barrels were made by AyA (in Spain) as an additional pair some years after the gun was made, but it is my understanding that they were fitted and proofed in the UK.

Mmm. Odd one. 3 inches is, of course, actually 76,2 mm. But that ,2 mm is only about 8 thou in Imperial.

[wymberley]

9 minutes ago, JohnfromUK said:

Seeing this thread 'revive' reminded me that I did a further investigation into my gun with the  'odd' proof combination of 1200 Kg and 70mm chambers.  (see previous page post of 9th July where there is a photo of the proof marks). 

I measured the chambers using a plug gauge.  A 'normal' AyA proofed for 70 mm shows the plug gauge drops in to slightly over 2 3/4"  (my gauge is Imperial).  The 1200 Kg proof barrels, my gauge drops in to near dead on the 3" marker (i.e about 7/32" longer chambers). 

A hypothesis might be that these were intended to be 3", but were just too short for the proof house to accept that the chamber was 76 mm (using their formal 'standard plug gauge").  The barrels were made by AyA (in Spain) as an additional pair some years after the gun was made, but it is my understanding that they were fitted and proofed in the UK.

That would still make perfect sense - right or wrong.

[JohnfromUK]

8 minutes ago, London Best said:

Mmm. Odd one. 3 inches is, of course, actually 76,2 mm. But that ,2 mm is only about 8 thou in Imperial.

My gauge is a 'home made' anyway and for the life of me I can't remember exactly what dimensions I used or where I got them from.  It is a stainless steel solid cylindrical plug, a not much looser than sliding fit in the chamber.  There are rings turned into it to mark the lengths.   In any case, with the front of the chambers being a (sort of) cone, the whole thing is open to some variation from the diameter of the gauge etc.

7 minutes ago, wymberley said:

That would still make perfect sense - right or wrong.

It does sound plausible - and in fact, since I (who uses 3/4 oz at clays and 1 oz at live quarry) am extremely unlikely to want to use 3" magnums, it is of no material consequence to me!  Just one of those strange 'shooting anomalies'!

[Guest cookoff013]

I know the minimum size for every cip chamber is chamber+2mm.

[JohnfromUK]

30 minutes ago, cookoff013 said:

I know the minimum size for every cip chamber is chamber+2mm.

My gauge (which is home made) is a 20 mm  (actually measures 19.98 mm) plug with near enough 'square' shoulders.  The accuracy of the marker ring placement would be better than +/- 0.25 mm I think.  See photo.  I can't remember if I followed any CIP standard drawing, but it was made as a guide to check, not definitive tool.

Chamber sizes are in Appendix 1 on page 41 here: https://www.gunproof.com/downloads/rules-proofing

I have not located the 'go/no go' gauge sizes, though I have not tried very hard.  For 12 bore, chamber (at the start of the forcing cone) is a minimum of 20.3 mm and the length 76.2 mm plus (as you say +2.0 tolerance)

[Guest cookoff013]

https://bobp.cip-bobp.org/en/tdcc_public?page=1&cartridge_type_id=7

shotguns now need a minimum of +2mm to be called that chamber, here is an example.

70mm gun, chamber measures 72mm = 70mm gun correct, gets a stamp.

another

 gun goes to proof, chamber measures 71mm, can only go for 2.5" or 67mm next catagory. 

but that never happens, what does if a gun gets alterd from 70mm to 76mm needs to be 78mm, might not be enough meat. 

76mm chambers are a minimum 76mm +2mm. if you are using a modern go/no go gauge, it would have +2 on it. 

 

shotguns are funny things really. the difficulty is the legeslation of what a gun is and min max dimensions of barrel and chamber. 

the 12gauge chamber is actually slightly tapered and starts at about 800tho. in old money. the figures after are the tollerences for the "forcing cone" (fired shell are the total length,).
the forcing cone has minimal room for "manufacturer interpretation".
the bore size is open to  manufacturers opinion, with optibore, tribore, over bore and the silly mossberg 10gauge barrel on a 12gauge chamber (that was the first 12/89mm).
 

the cip regs are there, i know we are looking at dated guns, but back then, most guns were made to saami and european specs not to mention the indipendent prroof evaluation. to which the cip hope to homologue all proof houses.

cool.

also to add, there are pressure barrel dimentions. these have smaller tighter specs.

[K.K.B]

So I have a slab of Pigeon Extreme 5-34g, but I have no idea if these would be safe to use in my gun (even though a 3" chamber with       2 3/4" cartridges) I am out tomorrow and would like to use them. Does anyone know the service pressure of these cartridges and if they are ok to use in my No.3?

[TIGHTCHOKE]

4 minutes ago, K.K.B said:

So I have a slab of Pigeon Extreme 5-34g, but I have no idea if these would be safe to use in my gun (even though a 3" chamber with       2 3/4" cartridges) I am out tomorrow and would like to use them. Does anyone know the service pressure of these cartridges and if they are ok to use in my No.3?

Should be on the box.

[K.K.B]

16 minutes ago, TIGHTCHOKE said:

Should be on the box.

I did look, but couldn't see anything and it's not listed on the website either.

[Gerry78]

If them pigeon power 2 3/4 cartridges you will have no problem using your aya no3 

[wymberley]

Gamebore. No problem. Although it has to be said that it's easier to shoot pigeons if they're in the same county as you using just an ounce of something. At the price and size of those I'd keep them for some high pheasant.