12g/20g PATTERN?

[BIG 5]

I like to shoot a 20bore for game most of the time and find it does the job very well. If using the same load as a 12g, same choke and same target distance, what difference is the pattern diameter. Is there any technical data to show any real difference without having to conduct your own experiment??

[mickmep]

my understanding is that with the same cartridge load and choke they pattern pretty much the same.

someone else may have some more in depth info than this, sure there was a post about this on here not so long ago.

[utectok]

I have read that.410 28 and 20 all pattern the same that is the chokes spread the shot in a pretty similar way although obviously there is less shot in a lighter load. Seems counter intuitive I know but apparently so.

[wymberley]

Hi,

The answers to your 2 questions are none and no. The pattern from a similar choke on any bore is the same. Yes, there is loads of technical information about which will reflect that fact but the problem is is that it is definitive, ie, it sets the nominal standard. The same round fired from another gun of the same choke can and usually will pattern differently. Similarly, equally loaded but different rounds fired from the same gun will do likewise. The only way to accurately check how any gun/cartridge combination is performing is to do a pattern test. Just to give you an idea, because I'm somewhat untidy, the page is still open on a scientific report that I've just been using and a pattern test results from the same barrel for the same cartridge batch showed a variation of 8% over the 10 rounds fired. You will appreciate that this is almost the difference between, say, IC and 1/2 choke.

Cheers

[gixer1]

so if a 12b and 20b both fired a 32g no6 through the same choke say 1/2, would it be the same pattern and hit with the same force?

 

I always wondered this as I shoot a 20 ans 12, if you think on it as a drinks straw and a toilet roll tube and you blow the same amount through them you technically get more velocity in the straw, would the same principle apply to a 20 and a 12??? which could mean the 20 would hit harder?

Edited January 28, 2010 by gixer1

[wymberley]

so if a 12b and 20b both fired a 32g no6 through the same choke say 1/2, would it be the same pattern and hit with the same force?

 

I always wondered this as I shoot a 20 ans 12, if you think on it as a drinks straw and a toilet roll tube and you blow the same amount through them you technically get more velocity in the straw, would the same principle apply to a 20 and a 12??? which could mean the 20 would hit harder?

Hi,

Let me say, that when talking about what happens inside the barrel, internal ballistics, I am well outside of my comfort zone. Bearing that in mind, mate, I think the answer is yes, same pattern (for sure) and the same force. This is because you could blow down your two tubes with differing effort for each and get the same velocity. Cartridge manufacturers load to obtain the same energy for a given shot/bore size. OK, they each have a preferred MV but in reality there's no great difference and this tends to equal out down-range anyway.

Cheers

Edited January 28, 2010 by wymberley

[flytie]

so if a 12b and 20b both fired a 32g no6 through the same choke say 1/2, would it be the same pattern and hit with the same force?

What are you, an American? 36g through a twenty, must be some kind of a masochist If you read Gough Thomas's book Shotguns and Cartridges for Game and Clays, there is a piece on shot patterns from 12 bore and 20 bore shotguns and they do work out as being very similar, also published was an article in Shooting Times by Lew Potter which drew the same conclusion, by test.

 

Unless you are using a gas semi-auto, which dampens felt recoil by spreading the actual recoil over a longer period, comfortable loads through a twenty bore follow the same formula as loads through a 12 bore do, weight of gun = 96 times the weight of shot. This is a layman's easy to follow version of the formula used by gunmakers. Basically 1oz of shot to 6lbs of gun. So for normal game shooting an o/u 20guage weighing 6lbs 4oz will fire up to 30g loads without being too uncomfortable, depending on the manufacturer obviously.

 

36g could be used in wildfowling I suppose, when very few shots will be fired compared to a game shoot, but it would be lively

 

ft

[gixer1]

What are you, an American? 36g through a twenty, must be some kind of a masochist

ft

 

 

I said 32g (to be honest they were the only fibre wad game cartridges the shop had when i went in and they seem quite good (express brand) I was shooting Eley VIP's which were 30g i think and they were fine too...

 

 

Gixer

Edited January 28, 2010 by gixer1

[flytie]

I said 32g (to be honest they were the only fibre wad game cartridges the shop had when i went in and they seem quite good (express brand) I was shooting Eley VIP's which were 30g i think and they were fine too...

 

 

Gixer

Beg pardon, must remember to put my glasses on before replying

 

ft

[gixer1]

Beg pardon, must remember to put my glasses on before replying

 

ft

[sitsinhedges]

so if a 12b and 20b both fired a 32g no6 through the same choke say 1/2, would it be the same pattern and hit with the same force?

 

I always wondered this as I shoot a 20 ans 12, if you think on it as a drinks straw and a toilet roll tube and you blow the same amount through them you technically get more velocity in the straw, would the same principle apply to a 20 and a 12??? which could mean the 20 would hit harder?

 

No because the different calibres use different types and amounts of propellant to achieve the same ultimate velocities in the respective cartridges.

[gixer1]

But the propant grammage is the same, so do you mean the quality/burn rate is different?

 

Regards,

 

Gixer.

[Beretta28g]

The best advice i can give is buy a copy of Gough Thomas Shotguns and Cartridges for game and clays.

 

It will explain everything.