Any Ballistic evidence for 12 vs. 20 bore at 28 grams?

[HistoricBore]

I would be curious to know if any scientific studies have been undertaken about comparing the patterns and shot string length between a normal 12 bore 28 gram loading (2.5" case) and an equivalent 28 grams fired from a 20 bore, probably a 2.75" case. Choke used should be the same of course, say half choke.

I currently use an old Webley 700 weighing 6.8 lbs but may wish to transfer to an over-under. As these are so heavy perhaps a 20 bore would be the answer, but wonder if the longer shot string has any real effect. Surely with modern digital photography an image of the shot string could be captured? Do the cartridge manufacturers do this sort of research?

Over to the experts....

Historic Bore

 

[sh1kar]

Gough Thomas will no doubt have had the answer
S

 

[Rhodesianjess]

Shotguns and cartridges for game and clays.
Well worth a read. Have you considered a 16 bore, ballistically a square load throwing excellent patterns in traditional weight loads.
Bear in mind non toxic are nigh on non existent in 16 bore.
Available in o/u barrel configuration too these days.

 

[mealiejimmy]

Not in the least scientific, but since the shot is coming out of a smaller hole, you'd think that the 20 bore would produce a tighter pattern and therefore a longer shot string
You don't hear many good game shooters saying that a 20 bore can't kill effectively.

Cheers

Bruce

 

[HistoricBore]

Hi chaps

I have just ordered a copy of the Gough Thomas book, but it is 45 years old now, and powders, crimps etc. have improved, surely. What about some photos?

HB

 

[Rhodesianjess]

According to Gough Thomas,much the same size pattern at normal distance, just less pellets in it. Shot stringing much talked about, very difficult to see any difference IMO with 12/16/20.
410 can be seen,as long as you in front you generally kill quarry. Best seen when shooting ground game,long string visible.
Modern shotgun loads are so varied that you can match a load to your requirements, either recoil or quarry. One gun shooters use this to their advantage.

 

[Rhodesianjess]

Hi chaps

I have just ordered a copy of the Gough Thomas book, but it is 45 years old now, and powders, crimps etc. have improved, surely. What about some photos?

HB

Don't know of any but they must be accessible on internet.
Is it recoil or weight of weapon that prompts your query, assuming that not too personal a question?

 

[Sika98k]

Whether the argument of a “square load” still holds with advancement of shot,powders, wads and crimps I don’t know.
but a 30gram load in a 12 bore and a 25 gram load in a 20 bore are considered to be “square loads”. The height of the shot column is the same as the width. This produces a good pattern, theoretically at least.
i have never understood why people buy modern 20 bores weighing the same as a 12 bore and then push 30+ gram loads through them. My vote goes for a 16 bore shooting 26 grams.
Gough Thomas wrote some great books to read over lockdown.

 

[Rhodesianjess]

Whether the argument of a “square load” still holds with advancement of shot,powders, wads and crimps I don’t know.
but a 30gram load in a 12 bore and a 25 gram load in a 20 bore are considered to be “square loads”. The height of the shot column is the same as the width. This produces a good pattern, theoretically at least.
i have never understood why people buy modern 20 bores weighing the same as a 12 bore and then push 30+ gram loads through them. My vote goes for a 16 bore shooting 26 grams.
Gough Thomas wrote some great books to read over lockdown.

All loads you mentioned are traditional. You would be horrified by what I pick up around pegs, yesterday a sportsman using a 20 was firing 32 grams of 5s at my birds, not very successfully either according to the pickers up.
Regularly find 12s in 36 gram 4/5 , once last season gamebore buffalo . Bloody fox drive cartridges!

 

[Sika98k]

All loads you mentioned are traditional. You would be horrified by what I pick up around pegs, yesterday a sportsman using a 20 was firing 32 grams of 5s at my birds, not very successfully either according to the pickers up.
Regularly find 12s in 36 gram 4/5 , once last season gamebore buffalo . Bloody fox drive cartridges!

Horrified ? Not at all, seen exactly the same lying around the pegs or guns asking me to find some particular favorite cartridges for them. Still I’m jealous, the pheasant season starts here today and it’s banned because of our lockdown. Go figure !

 

[Freeforester]

1:96 ratio of gun to charge weights, when a decent 12g game gun weighed 6lb 6oz. 1 1/16 oz (30gr) being ideal.

Injun more important than arrow..

 

[Rhodesianjess]

Horrified ? Not at all, seen exactly the same lying around the pegs or guns asking me to find some particular favorite cartridges for them. Still I’m jealous, the pheasant season starts here today and it’s banned because of our lockdown. Go figure !

Hope things only get better, hopefully you'll be out before end of season with 16 over your arm.
My personal choice too by the way

 

[HistoricBore]

I did see a nice Rizzini side by side BR550 in 16 bore with fixed chokes, built on their 20 bore action. Only one trigger though...

HB

 

[Rhodesianjess]

I did see a nice Rizzini side by side BR550 in 16 bore with fixed chokes, built on their 20 bore action. Only one trigger though...

HB

If your budget will allow it, have a look at 16 bore Rizzini round action, around£4k.
I've shot with one, superb weapon. Single selective trigger though.
The odd Browning turns up in 16 now and again, reputation speaks for itself.

 

[Foxyboy43]

IMO this Comparison is a bit of a pointless exercise - I bought a 20 more than 30 years ago - my experiences since tell me that 28gms out of the 20 will deal with any game quarry at all (acceptable) 12 bore ranges and handle better. 12 bore only used for geese cos of longer ranges/heavier charges etc. since then. Nuff said!

 

[Tim.243]

All loads you mentioned are traditional. You would be horrified by what I pick up around pegs, yesterday a sportsman using a 20 was firing 32 grams of 5s at my birds, not very successfully either according to the pickers up.
Regularly find 12s in 36 gram 4/5 , once last season gamebore buffalo . Bloody fox drive cartridges!

Some time back I was on an invite day with 32gm 6's, hit some nice birds centre pattern, come lunch time
a comment came up on " What you using Tim"? 32.6 Oh we only use 28gm...

Had you said in the briefing of does and don'ts I would have used yours...As you said nothing I used mine lol

 

[Rhodesianjess]

Some time back I was on an invite day with 32gm 6's, hit some nice birds centre pattern, come lunch time
a comment came up on " What you using Tim"? 32.6 Oh we only use 28gm...

Had you said in the briefing of does and don'ts I would have used yours...As you said nothing I used mine lol

Always tickles me how shotgun shooters assume that their load will work well in different gun/ choke combination. I often ask how a particular cartridge patterns at a pattern plate in their gun,blank stare is quite often the answer.
Rifle shooters tend to experiment a bit then settle on a load, based on results at target. Different strokes etc I guess.

 

[Tim.243]

Always tickles me how shotgun shooters assume that their load will work well in different gun/ choke combination. I often ask how a particular cartridge patterns at a pattern plate in their gun,blank stare is quite often the answer.
Rifle shooters tend to experiment a bit then settle on a load, based on results at target. Different strokes etc I guess.

I did add that I shoot their foxes with a 95gn round just to make sure..

 

[Magnificent 7]

All loads you mentioned are traditional. You would be horrified by what I pick up around pegs, yesterday a sportsman using a 20 was firing 32 grams of 5s at my birds, not very successfully either according to the pickers up.
Regularly find 12s in 36 gram 4/5 , once last season gamebore buffalo . Bloody fox drive cartridges!

I use 36g 5 as my go to.cartrodge all season and pick and choose what birds I shoot id rather go home. remembering the dexent birds than hit some no challenging bird myself I suppose its horses for courses

 

[Rhodesianjess]

I use 36g 5 as my go to.cartrodge all season and pick and choose what birds I shoot id rather go home. remembering the dexent birds than hit some no challenging bird myself I suppose its horses for courses

If it works for you then it's the right cartridge. Rather you than me though with a light SBS game gun on a biggish day, some cartridges thump a bit.
I chicken out and use light loads of I'm going to firing a lot, generally with a heavy gun too.
As you said,horses for courses.