Gentlemen: Because I was first introduced in to that special universe of fine sporting guns, which event presaged later glorious days afield, when as a youth I proudly took hold of the early Prussian
Charles Daly high-grade 16-bore bore side-by-side ejector gun my grandfather broke open and held out to me, I have been a lifelong aficionado and proponent of the mid-bore. At least it has worked in every situation appropriate to its use, and in the knowledge of its limitations, for over 50-years of personally chasing and shooting a wide variety of upland game birds across the farms, fields, plains, piney woods, marshlands, old orchards, and deciduous forests and woodlots of our home country. Somehow it has always seemed just right to me, in whatever configuration you find it. I own and shoot several mid-bored antique side-by-sides, though like you, I am sure there is that one most favored 16-bore gun. My current favorite is a light 16-bore
Westley Richards game gun, circa 1891.
My universal use shot size is no. 7, although for heavier upland birds I will accordingly switch to application-appropriate load weights of no. 6 or even to no. 5
lead shot. I remain cautious respecting bismuth-loaded or other types of lead alternative cartridges (with the exception of steel shot as required), which is probably entirely due, at least in my particular case, to limited experience with such cartridges. I might also attribute their non-use to suspicions attendant to one of a certain age, together with the factors of affordability, availability and supply. (If ducking, as opposed to upland game shooting, I use instead my custom 12-bore
Merkel 200E over / under, the only 'modern' gun I own, because it can safety digest steel shot pellets with its less than full choke modern steel barrels without damage.)
The circa 1891
Westley Richards shown below, which is a 16-bore with 2-1/2 inch chambers, emulates that long ago though not forgotten
Charles Daly game gun. With its 28-inch solid rib Whitworth steel barrel set attached, this lithe
Westley Richards weighs 5 lbs. 11 ozs. Remark the newly re-browned fine damascus barrels depicted resting on the (Kirk Merrington's) workbench immediately above the
Westley Richards, which are the beautiful Oxford pattern damascus barrels intended for shooting upland game often attached to the 20-bore
Westley Richards gun mentioned in the text below; although, given then prevailing circumstances afield, the 1/4- and 1/2-choke 26-inch steel barrels made for and fitted to this 20-bore by the renowned
William Ford in 1933 are naturally substituted for use against farther rising and 'tougher' birds in those situations requiring more choke, as well as needing heavier and greater weight of shot (say, for example, 3/4- or 1-ounce of no. 7 or even no. 6 lead shot).
Nonetheless, the Special Quality 16-bore
Westley Richards above is steady when pointed quickly or deliberately with my leading right-hand (I am left-handed), and handles 3/4-ounce 'lite' loads of nos. 7 or 8 shot from RST with aplomb, which is a good shot-weight diet for a light game gun with 124 year old wood. The left barrel of the Damascus barrel set is choked .010 or improved cylinder and the right barrel .005 or skeet. As it has my complete confidence, it is most often chosen for close-shooting game birds. The steel barrel set mentioned above for the 20-bore gun is used for greater distances because of the tighter patterns produced out to 40-45 yards.
My second place small bore is a circa 1882 "Best Quality"
Westley Richards 20-bore, which at 6 lbs. 7 ozs. weighs considerably more than its younger cousin obviously, due to the fact it was supposed to have been completed as a 16-bore originally, and thus loses one of the prime advantages of a small bore gun. Although, with 3/4 oz. loads of nos. 7, 8 or 9 shot, and if properly employing its Skeet 2 (.010) and 1/2-choke (.020) 28-inch damascus barrels, a better game gun for the common quail has not been invented. (
Note: The subject 20-bore is shown below cased with its two barrel sets and with some accessories; although, I would emphasize that this photograph is that of the dealer from whom it was purchased. The image shown does not, of course, evince the excellent results of the subsequent professional restoration works performed by Abe Chaber and Kirk Merrington.)
The aforementioned 16-bore
Westley Richards, however, is my unchallenged favorite for pointed Texas quail and for Upper Midwestern or Northeastern grouse. The mid-bore works equally well too for close-rising early season or preserve-reared pheasants.
For late season pheasants, or whenever longer shots and heavier, wilier or running birds are anticipated, I instead case and take afield the circa 1893
W. W. Greener Grade 60
facile princeps self-acting ejector, in 12-bore with 2-1/2 inch chambers and with its 30-inch fine "Silver Steel" damascus barrels installed, which game gun is depicted immediately below. It also digests only appropriate handloads for elder guns or is fed
RST loads using an ounce of no. 7 shot, or larger shot, in its 1/4-choke and improved modified damascus barrels.
So as not to forget the big bores, the 2-5/8 inch or 2-7/8 inch chambered 10-bore is one of my great favorites. It will do just about everything you should expect of a gun firing lead shot. Until its popularity diminished around the early 1890's, the 10-bore was considered the
nonpareil upland game gun. With one in hand, you may contemplate the endless, unturned prairies that once existed and the varieties of larger game birds that lived their lives and flourished in and amongst the fields of one-time lush hedgerows and grasses that provided a purpose for the larger bore.
I use my antique 10-bores for pheasants with appropriate low pressure loads utilizing 1-1/8 ounces of no. 6 or 5 shot, in the main, and even for swans on special occasions, as they can still be taken with lead shot in Texas. The circa 1872-1873
Charles Daly hammer-gun (a pre-Lindner
Schoverling & Daly imported gun) below, which I have not yet taken afield, but will this coming fall season, is a 10-bore with 2-5/8 inch chambers choked modified in each 30-inch black and white "
Manufacture Extra" damascus barrel, which will more than suffice for anything encountered.
It is always a pleasure to find or correspond with others who also take their fine guns afield and use them as intended, and from their actual use come to better appreciate and enjoy our temporal ownership and our fortunate days afield with a fine side-by-side gun even more. With my
Best regards to all,
Edwardian
Postscript: I have greatly enjoyed and learned from the gentlemen's much appreciated comments addressing their choke and size of shot preferences for use against varieties of quail, such as the plucky Gambel's quail. I personally think that for general purposes, especially when shooting quail (whether we are discussing Mr. Bobwhite, Mearns, Scaled, or similar species of quail) over dogs, the more open the choke the better, say improved cylinder up to light modified, with the modified choke in the second barrel as the outer extreme.
Granted, shooting the Gambel's quail can too often require a different set of chokes and shot sizes, depending on the environment and current temperament of the bird, yet I have never had occasion to need anything more than a second barrel choked modified for them. Although there are indeed some acquaintances of mine who eschew all alternative combinations other than guns with full-choked barrels and who use nothing less than no. 6 lead shot when hunting this bird without the assistance of a dog on its own ground. I must assume that they too are successful, or they would not keep to this regime. So there must be more than one way to accomplish the instant task.
Admittedly, my style of shooting largely governs my choice of choke. Also, I shoot behind a dog or dogs more often these days and am an exceedingly aggressive shot, in that I usually fire my first barrel within 20-yards or so of the intended receiver of my shot pattern, which knowledge in turn helps me to reasonably determine the degree of choke I should use.
As well, if I have ever shot a quail (or attempted to shoot one) at a distance of more than 40-45 yards from my gun, I do not recall having done so intentionally. Beyond that range, I would be concerned about crippling the bird, and will withhold my shot, no matter the bore, choke or shot size used. When using a 16- or 20-bore gun within that 40-45 yard range with my standard 3/4 ounce load of no. 7 lead shot, and coupled, If necessary, with the gun's modified or 1/2-choke barrel, execution has been more than adequate historically. In environs of the thick, entangling and spikey stuff, where sighting of the bird is but fleeting at best and most often at very short distance, the average distance to the intended target and my gun will likely be 20-25 yards. At those short distances, even the improved cylinder choke, combined with the 3/4 ounce loads of no 7 lead shot, will perform and has performed exceptionally well.
Come on in, but you won't leave like you started, and you better have some forceps for cactus spine extraction and a laceration repair kit 
