Most rimfire is even larger than .222. The ones i've checked run .223 to .224. Usually CCI is .224
Don't confuse the cartridge bullet diameter with the rifle bore and lands diameter. Many cartridges are made a little large, so they perform well in older or worn out firearms.
As to the OP's question. I have swaged jacketed bullets from .338 to .330 for an old European military rifle. Complete core separation happened, the ammo was the worst I ever shot from that rifle (and I was using a proven "Good" load). The lead goes down to a diameter inside the jacket and , depending on alloy, my spring back .0005 or less. The jacket goes down to the die diameter and also depending on alloy may spring back up to .004. I have had cores "Rattle" around inside the jacket. It is a total waste of resources!
On lead bullets, it is a different story! I have a 300 grain 45-70 bullet mold, with a harder alloy it casts to .467". It is all I can do to size them to .459". I size all of those castings to .459, then size some of them again to .454 or .452 for use in 45 Colt. Lots of work, but saved me from buying another mold! If you ever try this, smear some bullet lube on the first to reduce a little of the friction.
As to the question about "Are 22-250's in .224" also?" Yes as stated, all 22 center fire rifle cartridges made post WW II are in .224. There are some pistol rounds that are exceptions. There is ONE exception to that rule: 22 Savage High Power. It uses a .228 bullet (Hornady was the only place you could get them for years,) and these are Semi-Round Nosed and usually 80 grains. You won't confuse them for anything else!
Now onto your 22-250. These rifles (of almost any brand) are very accurate! 22 FMJ bullets are of mass production to be cheep, and are of usually less than stellar accuracy! My favorite bullet for all of the medium case sized 22 Center Fire Cartridges is a 50 grain polymer tipped bullet. There are 4 brands; Hornady, Sierra, Nosler, and Combined Technologies (Winchester & Nosler). They are mostly the same price with the CT's being the most expensive. Of my 12 firearms (9 rifles and 3 Contender barrels) every one has a preference as to which one it likes, except, I have 1 rifle that likes two brand equally well. So I keep boxes of each brand in stock, and whatever I have the most of, I use for load development. Then I load up 5 of each bullet with that best load and see which the gun likes best. It is extremely unusual for a gun to like 2. I have a 1:9 twist Savage 223, that doesn't like any bullet that light! I likes 75 grain A-Max (Hornady) bullet and shoots them very well!
Sierra has a very good loading manual. It has a recommend load for accuracy for every cartridge, THIS is where I start (and usually am satisfied with it!) 22-250, if a well used rifle, can have an eroded throat, that may require seating the bullet out further. Then I go for the brand selection.
Have fun finding out just how well your gun can shoot!
Ivan
