Each shotgun uses a different percentage of the pellets in a shell. Shotgun Model A uses 50% of the pellets in a shell with, we'll say(for simplicity's sake), 100 pellets. This means it fires 50 pellets, discarding the other 50. Shotgun Model B uses 70% of the pellets, using 70 and discarding 30. Shotgun Model C uses 80%, Model D uses 90%,(<---Oxford Comma) and Model E uses a whopping 100% of the pellets in the shell.
Why would shotguns be made like this, you ask? Profit, I say.
See the shotgun manufacturers realize that by producing shotguns of higher and lower value they could easily make more profit than making a single model that always uses 100% of the pellets in a shell.
Say making a shotgun costs an average of $50(convert that on your own Europeans). If they then sell this for $70 they will always make a $20 profit. They average 500 sales a year(a low number I know, but this is just an example). They average a yearly profit of $10000. However, not everybody has a disposable income that will allow them to pay $70 for a shotgun(though I find that poorer people still own more guns than the middle class person[or maybe that's just a stereotype, I really don't know]). To make their item more affordable to the poor man, thus making more sales with a wider audience, they decide to slash the price to $60, always making a $10 profit. With the wider audience they average 1200 sales a year. They average a yearly profit of $12000.
Here's where they get smart. They decide that, while they could make their current standard shotgun and make their current average profit, if they make different models, and charge corresponding prices depending on quality they could make much larger profits.
So, they decide to make their current product the Model E Shotgun, jacking the price up to $170, making a $120 profit for each sale. A nice increase. This will be the rich enthusiast's/collector's shotgun. They sell 40 a year. Total profit is $4800
For the Model D Shotgun, they, at a nominal extra cost, place a limiter on the number of pellets used per shell. 90% of the pellets are fired. The price is $150. Profit- $99. Sales-80 a year. Total Profit- $7920
For the Model C Shotgun, they fire 80% of pellets. Price is $110. Profit- $59. Sales- 140/yr.
TP- $8260
Model B-70% pellets. Price- $90. Profit- $39. Sales- 550/yr. TP- $21450
Model A-50% pellets. Price- $61. Profit- $10. Sales- 390/yr. TP- $3900
Old System Yearly Profits- $12000
New System Yearly Profits- $45700
Which system works better?
Is that enough rationale for you, Mr. OP?
TL;DR- Evil Capitalists.