Sxs choke

[NorfolkAYA]

hi all,

 

Does anyone know what .719 dictates in choke size? 

 

Cheers pete 

[dipper]

If bore size is 729  should be 1/4

[bluesj]

1/4 ish but it depends on barrel dimensions.

[JohnfromUK]

The amount of choke is related to (but not defined as) the difference (constriction) near the muzzle compared with the main (near enough parallel) length of the barrel between the end of the cones and the start of the choke.  The main bore is typically measured 9" forward of the breech.  For a 12 bore the nominal figure is .729" - but many guns differ from this a bit - and may also have been fine bored since original proof.

The choke measurement is the smallest diameter that is measured as the gauge passes through the choke area.  If this is .719 - and the main bore is .729, there is .010 constriction, which is (as has been said) would be expected to give about 1/4 choke patterns.

Two things to note

1. Strictly - choke is the pattern achieved and any estimation of choke by barrel measurements alone will be an approximation and will vary a bit with different cartridges etc.
2. Many guns have been altered over the years - either by a little fine boring (usually to remove pitting/corrosion) - or having the choke altered, or both.  hence any stamped measurement really should be checked if you are to use it for estimating things.

In summary, the stated 1/4 choke above is the best estimate (and correct answer) based on the single stamped mark of .719 being the choke - but it might be erroneous and the real test is how the gun patterns with the cartridge you use.

[NorfolkAYA]

Thanks all, seems that my baikel is actually 1/4 1/4 then. 

 

Cheers pete

 

[London Best]

4 minutes ago, NorfolkAYA said:

Thanks all, seems that my baikel is actually 1/4 1/4 then. 

 

Cheers pete

 

You do realise that if your gun is stamped, say, .719 on the barrel flats, then that is the size of the bore at proof and has nothing to do with the choke?

[TIGHTCHOKE]

27 minutes ago, NorfolkAYA said:

Thanks all, seems that my baikal is actually 1/4 1/4 then. 

That's surprising to have the same choking in both barrels, probably not how it started out!

[wymberley]

24 minutes ago, London Best said:

You do realise that if your gun is stamped, say, .719 on the barrel flats, then that is the size of the bore at proof and has nothing to do with the choke?

Additionally and according to a PW member who knew, the length of the barrels can affect the choke. The pattern plate is your only answer.

[JohnfromUK]

London Best has raised a good point.  Do we know that the .719 refers to the choke?

If .719 was the proof dimension of the main part of the bore - (entirely plausible) - then they would both be the same.  .719 if measured with plug gauges could be up to .728 anyway as they usually used .01 increment plug gauges.  It is only fractionally tight for a nominal 12 bore - as many were.

[London Best]

I checked a Baikal only last week. It was stamped .719 and both barrels were a very close fit to a .719 plug gauge. Perhaps that is the size Baikal work to?

I have never checked another one.

[Gunman]

.719 has no relevance to choke size at all .It is a nominal bore size .

Choke bores can only be accurately measured buy comparing the bore size behind the choke and the choke size itself .Not all countries used the same choke percentages as we did in the UK often using degrees of .008" rather that .010" , the Spanish using a between system so each choke had its own range  of size .

Bore sizes were checked with a plug gauge . If a .729" plug was entered to the 9" mark  , then a .729" plug was tried . If this did not enter the bore would be stamped at the lower size even if it was actually .726".

With the importation of foreign guns in the 60's and 70's which were built using [evil IMHO ] metric sizes of .720" , .724" , & .728" inter mediate size plugs were used and the bore size was stamped accordingly at the discretion of the viewer , so it was possible to get a gun marked up as .729" that actually measured .727".

I have seem early Miroku's marked  by Birmingham at .719" ,  that measured .728" before this was realized . 

This all changed whet the British proof houses adopted metric markings and sizes .

[PeterHenry]

20 hours ago, wymberley said:

Additionally and according to a PW member who knew, the length of the barrels can affect the choke. The pattern plate is your only answer.

Thats intresting - do you know what bearing this has on the use of steel shot?

For instance, is it just the constriction at the end of the barell being 1/2 choke or under, or is it the overall 'choke', takeing into account factors such as barell length?

[London Best]

1 hour ago, PeterHenry said:

Thats intresting - do you know what bearing this has on the use of steel shot?

For instance, is it just the constriction at the end of the barell being 1/2 choke or under, or is it the overall 'choke', takeing into account factors such as barell length?

Barrel length has nothing to do with the choke, unless the barrels have been shortened and removed the choke, which is in the muzzles.

[wymberley]

2 hours ago, PeterHenry said:

Thats intresting - do you know what bearing this has on the use of steel shot?

For instance, is it just the constriction at the end of the barell being 1/2 choke or under, or is it the overall 'choke', takeing into account factors such as barell length?

I've not had to use steel for over 30 years and have no intention of doing so again so am not the bloke to ask. However, as I understand it, it is the choke itself that does the damage as it were. Unlike lead, soft iron doesn't give so something else has to when the quart is passed through the pint pot.

40 minutes ago, London Best said:

Barrel length has nothing to do with the choke, unless the barrels have been shortened and removed the choke, which is in the muzzles.

I thought TIGHTCHOKE above was going to have the answer from what he said. Was last week's Baikal fixed choke and did you notice anything in particular?

[Scully]

3 hours ago, PeterHenry said:

Thats intresting - do you know what bearing this has on the use of steel shot?

For instance, is it just the constriction at the end of the barell being 1/2 choke or under, or is it the overall 'choke', takeing into account factors such as barell length?

I’ve never heard of barrel length having any bearing whatsoever on the chokes. 
You can put any steel shot you like through that constriction ( 1/2 ) without any cause for concern. 

[wymberley]

On 13/12/2020 at 18:35, NorfolkAYA said:

Thanks all, seems that my baikel is actually 1/4 1/4 then. 

 

Cheers pete

 

I'm afraid I give in. I've done countless searches and can only find that what I was looking for is pre 4th Jan 2009 when one of our Admin staff posted on that date that he  remembered seeing it According to a member who worked for the Baikal importers/distributors/call them what you will Baikal fixed chokes could be cones/taper only with no parallel element. A 28" barrel with 1/2 and Full choke would become a 27&1/2" barrel with 1/4 and 3/4 upon request. Should the barrels be chrome lined, as opposed to chrome steel, cutting them to suit would be a economic way of altering the choke although the ratio would remain.

[London Best]

1 hour ago, wymberley said:

 

I thought TIGHTCHOKE above was going to have the answer from what he said. Was last week's Baikal fixed choke and did you notice anything in particular?

The ‘last weeks Baikal’ to which I referred had been hacksawed to 24 1/4 inch barrels. It had stamps to say it was Birmingham proofed at .719 inch in the bore. My .719 inch plug gauge was a close fit right through, and I formed the opinion that even a .720 inch plug ( which I do not possess ) would not have passed through, such was the fit of the .719”. (I am a precision toolmaker by trade.) Neither barrel carried any choke whatsoever.

[wymberley]

4 minutes ago, London Best said:

The ‘last weeks Baikal’ to which I referred had been hacksawed to 24 1/4 inch barrels. It had stamps to say it was Birmingham proofed at .719 inch in the bore. My .719 inch plug gauge was a close fit right through, and I formed the opinion that even a .720 inch plug ( which I do not possess ) would not have passed through, such was the fit of the .719”. (I am a precision toolmaker by trade.) Neither barrel carried any choke whatsoever.

I fear the missing 3&3/4" holds the answer!

[TIGHTCHOKE]

5 minutes ago, London Best said:

The ‘last weeks Baikal’ to which I referred had been hacksawed to 24 1/4 inch barrels. It had stamps to say it was Birmingham proofed at .719 inch in the bore. My .719 inch plug gauge was a close fit right through, and I formed the opinion that even a .720 inch plug ( which I do not possess ) would not have passed through, such was the fit of the .719”. (I am a precision toolmaker by trade.) Neither barrel carried any choke whatsoever.

There would be no degree of choke if the barrels had been cut down and the chokes removed.

Why are some of you trying to re-invent the wheel?

[London Best]

1 minute ago, TIGHTCHOKE said:

There would be no degree of choke if the barrels had been cut down and the chokes removed.

Why are some of you trying to re-invent the wheel?

I’m not, it’s all the other boys.

I was just trying to explain things for the theory men.

Edited December 14, 2020 by London Best

[TIGHTCHOKE]

PW and this thread in particular do suffer from the over-thinkers!

Edited December 14, 2020 by TIGHTCHOKE

[wymberley]

3 minutes ago, London Best said:

I’m not, it’s all the other boys.

I was just trying to explain things for the theory men.

Nor me, I was in detention at the time.

[London Best]

2 minutes ago, TIGHTCHOKE said:

PW and this thread in particular do suffer from the over-thinkers!

It seems to me that the PW massiv in general appears to be obsessed with choke. 

[TIGHTCHOKE]

1 minute ago, London Best said:

It seems to me that the PW massiv in general appears to be obsessed with choke. 

And more importantly a high percentage of those that are obsessed with it fail to understand it (choke) and much of the rest of the weapons they use!

[London Best]

You noticed too!