RE: 12 guage v. 20 gauge
Peter Capstick wrote the definitive work on this very topic. It first appeared in Sports Afield, and later as a chapter in his fine book, "Death in a Lonely Land." It is titled, "Anything the 20-gauge can do, the 12 Can Do Better." Here is part of it:
...Let there be no misunderstanding; I am extremely fond of the 20 guage, but only within those areas of reasonable effectiveness... Look I often shoot a 20 when conditions permit. There is nothing wrong with proper loads in a 20. It is simply a fact that it will not perform as well, given even slightly extended ranges, as will the 12. Sorry, but that's the way it is...
...My affair with the 20-bore began with a graceful little Belgian import... 26 inch barrels that blended with a beautifully figured French walnut stock. She pointed where I looked, and got there faster than I could focus. I had bought her, I told myself, for the same reason I drank vodka martinis and fished a dry fly. It was simply a more sporting way to do things. Fifteen years have gone by now, and I still drift a Light Cahill and certainly still drink vodka. But I've had to swallow my illusions about the 20-gauge. She's just not enough gun for today's upland shooting.
A couple of years ago, when I was working for the travel division of one of the major arms companies, I had a unique opportunity to test the 20 against the 12 under varying conditions with a unique mixture of upland game. The company was just about to start marketing the 20-gauge version of their Japanese made over\under 12 gauge, both very attractive pieces of hardware. As I was scheduled for a jaunt through Europe and North Africa to make arrangements for some gunning trips the company would offer, it seemed logical that I, and the other men on the trip, tote along a few of the new 20s for sort of an informal field test.
The trip started in... Scotland... Using the 20-gauge field load of 2 1\2 drams eq behind one ounce of lead shot, we slogged through the heather and gorse for a week, getting some very fine shooting... Each day I would alternate between guns, switching to the 12 with 3 1\4 drams pushing 1 1\4 ounces of shot, carefully noting the results of each day's shoot in my notebook. After six day's sport, I tallied the results.
Taking care not to fire at birds much over 40 yards, I had bagged exactly 26 percent more red grouse with the 12-gauge than the 20, with the same number of shells. Of the birds knocked down with the smaller gun, 31 percent were still alive when retrieved, against 11 percent with the 12. Except for gauge, both guns were as identical as they could be; the same model and both choked improved-cylinder and modified. The figures seemed significant, I thought, but a week's shooting on one species is hardly conclusive.
Next stop was... Portugal... where we hunted red legged or Spanish partridge through the cork and olive groves. Much like chukars, hunting these birds on foot reminded me of nothing so much as ruffed grouse back home, except that the red legs were smaller, faster, and if you can believe it, wilder. Fernando Fernandes, twice pigeon-shooting champion of a country that takes shooting very seriously, was virtually stiff with laughter at the idea of taking on "perdiz" with the 20-gauge. The box score for the group proved he was right; more than twice as many birds had been taken with the 12 than the 20 under identical conditions.
A few hundred miles farther south... Moracco, where I joined the noted French shooter and gastronome, Bertrand des Clers, for ten days of magnificent sport with driven snipe, partridge, duck, and wild boar. Hordes of howling... Arabs... floundered through the flooded grasslands driving sheets of wintering Siberian snipe at us for six days. One of my shooting partners concluded after the next two beats that Moraccan snipe were "very small birds surrounded by vast quantities of air." It was a pretty accurate deduction in view of the performance of the little 20-gauge... these weigh no more than a few delicious ounces, small enough to slip, time and again, through the poorer pattern of the 20-gauge load of No. 9s we were throwing. After shooting snipe 3 days with each gun, I had killed exactly 66 percent more with the 12.
That trip shook the foundations of my love affair with the 20, a relationship that got even rockier after a dozen trips through Argentina and Colombia, where I kept the test going on tinamou, martineta, paloma, and torcaz, which almost exactly equal our quail, pheasant, doves, and pigeons in body size and habits.
Since 1969, as a professional white hunter in Zambia, Botswana, and Rhodesia, I have shot literally thousands of birds for food for myself and my clients - mostly guinea fowl, sand grouse, francolin, button quail and other species - with both the 12 and 20 gauges. The conclusion was inevitable: The 12 gauge, at normal upland ranges, will put more birds in your game bag under virtually any circumstances than will the 20-bore...
It goes on, going more into the math and other technical matters, as well as several other good points, and for anyone with access to the book, the entire chapter is well worth reading. I myself have several 12 and 20 gauges, and I too, have always had a love affair with the 20, but, much as I hated to face it, I, too, flat out put more birds in the bag with the 12 than the 20. I still use my 20s, but when I want birds, I reach for the 12 (or sometimes the 10, with ducks and geese). My own experiences have very much borne out Peter Capstick's writings.
Sorry about the length of this post, but I hope it will help someone else bag more birds the way this chapter helped me...
Vinny