How did being late to adopt breechloading technology affect the development and competitiveness of early British cartridge-firing sporting guns?
Interesting question. The French beat the Brits by about 20 years in practical, self-contained cartridges, and it was the French who developed the first 'modern' centrefire cartridges and guns around 1853. The incorporation of a 'base wad' into shotgun cartridges was patented in France in 1849, making cartridges and chambers gas-tight thereafter. The first British breech-loading guns, say, 1854-1860, were a mixed bag. They copied /bought/stole French designs, but makers were not quick to figure out how to handle increased pressures. Mainsprings were weaker than their French counterparts, and chamber sizes and cartridge materials/sizes were far from standardized —what fit in one gun might not fit in another. Cartridge quality differed batch-to-batch, and misfires and split cases were common. However, there was enough public attention and demand to force gunmakers and ammunition makers to improve their game, and by about 1860, many of the problems with breechloading guns were ironed out; it took more years before cartridge ammunition quality improved. It should be remembered that for the all-important 1860s, breech-loading shotguns were a toy of the rich, and while made-up ammunition could be bought from gunmakers, most bought primed hulls in bulk and had their butlers/footmen prepare and load their cartridges with their favourite powders and shot.
There was a LOT going on in those early years, in terms of design, manufacture, chemistry, and social changes. Eventually, Britain caught up and (some might say) surpassed its Continental competitors, but the USA, with its factory production tools and strategies, was also aiming to win the race.
A little-known aspect of the development of British cartridge guns was the push to adopt improved smokeless powders, which happened much earlier than is commonly recognized. I wrote about it here:
https://www.vintageguns.co.uk/magazine/gun-cotton-and-pinfires