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20 bore patterns better than 12?


Gungoesbang
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My over under 20 bore seems to take targets down much more effectively than my side by side 12 bore. Both have cyclinder and improved cylinder or equivalent chokes (20 multi, 12 fixed) but the 20 seems to dust clays/hits pheasants harder, where as the 12 often breaks the clays in two or into much fewer larger pieces. This is the same with a range of cartridges. Also, both guns fit nicely enough. Do 20 bore guns pattern better, and is this at all normal, or does my particular 20 pattern well/tighter or does my 12 pattern badly? 

Thanks very much. 

 

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20 doesn't inherently pattern better than 12,  its down to the cartridge and gun combination.  I have patterned my Perazzi with a number of cartridges and found the best ones for each given scenario (ie. clay or game).  I had a 20 for years and didnt notice it killing any better than my 12.  

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It may be that your 20 is throwing relatively tight patterns, whereas your 12 is throwing more open patterns.  Chokes are 'nominal' and vary quite a bit.  It could even possible that your 12 has been opened out by a previous owner?  You could always experiment on a pattern plate.

In times gone by, gunmakers bored guns and patterned them (sometimes with a cartridge specified by the owner/prospective owner) and paid a lot of attention to getting patterns very even, if necessary making minor alterations to the boring to get the right result, whereas most (all?) modern guns are bored to a set of dimensions.  There is no doubt that there is variation in patterns between guns.

A lot of words have also been written about all manner of 'magical' boring techniques - long cones, short cones, back boring, different choke profiles.  Much money has been spent following these doctrines.  Do they work?  Well, as the saying goes, "some say they do - and some say they don't".  My money will go on more practice rather than fancy boring!

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As tightchoke said, if you really care get them measured and also pattern it. In some cases what a manufacturer calls improved cylinder might vary by gauge (different constrictions that is).  Also, sometimes in smaller gauges the same nominal constriction will pattern tighter due to the smaller nominal bore size. You see it more in 28 and 410 but also with tighter constrictions in the 20.

 

my guess?  The 20 just fits you better  

 

Rick 

 

 

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Thinking can of worms really  in my opinion. Both are inherently capable, but one starts off already tighter than the other.Those patterns aren’t trumpet shaped you know, or at least not until they appear so on a pattern plate! ?

As dismissive as it appears this comment is; if you don’t put either pattern in the right place, neither is better than the other. 

At the same distance through the same chokes, I’m guessing the 20 patterns tighter. It has to doesn’t it? 

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1 minute ago, Scully said:

Thinking can of worms really  in my opinion. Both are inherently capable, but one starts off already tighter than the other.Those patterns aren’t trumpet shaped you know, or at least not until they appear so on a pattern plate! ?

As dismissive as it appears this comment is; if you don’t put either pattern in the right place, neither is better than the other. 

At the same distance through the same chokes, I’m guessing the 20 patterns tighter. It has to doesn’t it? 

It should.

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2 minutes ago, Scully said:

At the same distance through the same chokes, I’m guessing the 20 patterns tighter. It has to doesn’t it? 

If you take the definition of choke as the percentage inside a 30" circle around the centre of the pattern, then there for a given load (say 1oz), no, it should be the same.  However, 20 loads are usually lighter, so the number of pellets will be lower overall, and so pellets inside (as the same percentage) will be lower.

In my view, a 1oz  load fired through a half choked gun should be identical (same pellet count, same percentage, same circle) for both a 12 and a 20.

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I’m not into the scientific aspect of shooting , never have been. I just like to pull the trigger without too much thought going into it further than swing, but if you have two barrels with the same amount of shot passing through them, sent on by the same charge, at the same distance but through tighter tubes, you would think one has a tighter patten than the other. 

Doesnt it? If it doesn’t, but you’re killing what you shoot at, then does it matter? 

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11 minutes ago, Scully said:

I’m not into the scientific aspect of shooting , never have been. I just like to pull the trigger without too much thought going into it further than swing, but if you have two barrels with the same amount of shot passing through them, sent on by the same charge, at the same distance but through tighter tubes, you would think one has a tighter patten than the other. 

Doesnt it? If it doesn’t, but you’re killing what you shoot at, then does it matter? 

+1

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12 minutes ago, Scully said:

but if you have two barrels with the same amount of shot passing through them, sent on by the same charge, at the same distance but through tighter tubes, you would think one has a tighter patten than the other. 

No, not if they are choked such that they place (say) 50% inside a 30" circle.  The pattern will be identical.

 

2 minutes ago, winnie&bezza said:

If it doesn’t, but you’re killing what you shoot at, then does it matter? 

It doesn't matter in the slightest - especially as the pattern is the same.  In my view the original poster shoots better with his 20 - simple as that.

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1 hour ago, steve d said:

Which do you shoot more often? Ones OU and the other is SxS, very different sight picture and possibly double triggers?

I shoot them about the same now but I’ve had the SxS (12) for ages and only had the OU (20) for a couple of years. I have had the SxS fitted but not the OU, although the OU fits well. SxS is double trigger and OU single. I know they are very different and I shoot the 20 better, but I have no idea why. I’m going to try on a pattern plate. 

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Ammo can make a difference. I was planning shooting sporting clays with half and half this year but have recently found that my job lot of fiocchi 7.5 (english 7) Fblu are throwing such a tight pattern that using those in my gun I'm thinking of staying put or perhaps stepping down to quarter and quarter.

Nothing scientific, simply walked past the pattern plate and shot through the half choke at an unmarked part of it, at 35y measured by pace, and noticed that it is tighter than what I'd expect, plus I'm noticing there's much more dust coming off my kills.  

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On 10/02/2018 at 22:28, JohnfromUK said:

No, not if they are choked such that they place (say) 50% inside a 30" circle.  The pattern will be identical.

 

It doesn't matter in the slightest - especially as the pattern is the same.  In my view the original poster shoots better with his 20 - simple as that.

Correct. A twenty bore half choke will measure less constriction than a twelve to achieve the the same half choke pattern. If it is regulated by hand and on a pattern plate. 

For instance, traditionally half choke on a twelve is around .020 thou. with a .729 bore. On a twenty half choke is around .016 thou with .615 bore. 

The gun is then patterned and the choke tweaked accordingly. 

I know so many European guns with over boring like the Beretta 20's seem to have a bore of about .626 but the choke will/should have been opened/adjusted accordingly to accommodate for the larger bore to achieve said half choke.

And don't always believe what is stamped on the barrels. Someone sometimes has the chokes altered. 

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16 minutes ago, Fil said:

Correct. A twenty bore half choke will measure less constriction than a twelve to achieve the the same half choke pattern. If it is regulated by hand and on a pattern plate. 

For instance, traditionally half choke on a twelve is around .020 thou. with a .729 bore. On a twenty half choke is around .016 thou with .615 bore. 

The gun is then patterned and the choke tweaked accordingly. 

I know so many European guns with over boring like the Beretta 20's seem to have a bore of about .626 but the choke will/should have been opened/adjusted accordingly to accommodate for the larger bore to achieve said half choke.

And don't always believe what is stamped on the barrels. Someone sometimes has the chokes altered. 

Those generic ideal numbers as I’m sure you know the cartridge has a lot to do with this in each different gun.  

The patteren plate holds the true answer to choke not the stamps.  

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I`m no means an expert in such things (far from it)  but something that the pattern plate will not show is the shot string. Surely the 20 bore has a  longer shot string and maybe a bit more forgiving if one is well ahead of the target. Just my simplistic view, nothing technical.

OB

 

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47 minutes ago, Old Boggy said:

I`m no means an expert in such things (far from it)  but something that the pattern plate will not show is the shot string. Surely the 20 bore has a  longer shot string and maybe a bit more forgiving if one is well ahead of the target. Just my simplistic view, nothing technical.

OB

 

I also tend to think this. I have several 12 bores and a couple of 20 bores, o/u and side by side in both calibres. Over the past two seasons i have found the 20 bores kill far more efficiently than my 12 bores, especially if i use Eley . Zenith copper coated 5s. Why? i  don't know, i just know it works for me and several others that have made the switch to 20 bore.

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4 hours ago, Old Boggy said:

I`m no means an expert in such things (far from it)  but something that the pattern plate will not show is the shot string. Surely the 20 bore has a  longer shot string and maybe a bit more forgiving if one is well ahead of the target. Just my simplistic view, nothing technical.

OB

 

The shot string will travel very quickly past the target. You will simply miss if you are too far in front. There is no advantage in having a long shot string.

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