Interested to know why some people would choose .222 or .223 for a mid calibre?
Reasons to choose .222 and .223
Low cost ammo and easy to get hold of. They are both quieter than the bigger varmint rounds and are capable of being loaded deer legal. Also the rifles for these rounds are plentiful used and new, so you have a great choice and can usually find a bargain. Also .222 and .223 calibre rifles tend to be very accurate even out of light weight barrels and the barrel and mod heats up more slowly than the bigger rounds so you retain that accuracy for longer than a couple of shots.
That was really the point of my original post. How to get a newby into shooting with great kit at low initial outlay. Once the bug has really bitten, you can sell the dog, remortgage the house and pimp the wife out so you can buy all manner of exotic kit, but that should probably be the subject of another thread
An added advantage of .223, if you target shoot, is cheap full metal jacket ammo - if your rifle is safe with 5.56x45
Military Calibres and Cost
We are lucky in this country that we can have rifles in “military” calibres like 7.62x51 (.308) and .223 (nearly the same as 5.56 x 45). These calibres are very popular, so ammunition and loading components are plentiful and inexpensive relative to more obscure rounds. Also some of the army surplus ammo is very accurate. The rounds with the head stamp including a cross in a circle is particularly good. Other army surplus ammo is a bit variable and obviously FMJ rounds are no use on deer and though excellent for head shooting rabbits, hold together too well and can result in ricochets. Basically FMJ ammo is only safe and useful for rough sighting in when swapping scopes over or for target work. 7.62x51 is pretty much always ok to shoot in a .308, but some of the machine gun rounds are a little warm! 5.56x45 is best only used if you know the lead to the rifling is long enough in your rifle. A gun smith can advise you on that.
If you end up shooting ten rounds of surplus ammo to get a rough Zero, you’ve spent less than a fiver. I also use random reloads for sighting in. Way cheaper. None of this matters if you sight your rifle in once and leave the scope on there, but if like me you swap scopes around and like trying new kit, it’s handy having some cheap ammo to burn through.