Wait... Aussie gun laws restrict what calibres can be used in competition??
Yep. Our handgun laws are broadly similar to yours (10 round mags, be a member of a club) with a few extra pointless restrictions. Our minimum barrel length is 120mm for semi auto and 100mm for revolver so we can have a 4" revolver but not a Glock 17. Glock make the 17A just for us which has a small extension, looks like the restricted Glock 19 does in Canada.
We had the major gun buyback after Port Arthur in 1996 which resulted in removing semi auto rifles and shotguns from pretty much every one. Farmers can still get a semi .22 or shotgun but semi auto center fire rifles for anyone besides government and a few professional animal cullers is impossible. Handguns weren't affected as they have always been much more heavily restricted. This changed in 2002 after a licensed shooter (should never have been approved) killed two fellow students at Monash University which resulted in minimum barrel length, calibre restrictions and ten round mags as well as higher participation requirements and longer waiting periods. From first applying to being able to have your own pistol securely stored in your own safe takes about 8 months if everything goes smoothly but we tell new members to be more realistic and expect 10-12 months. You can still shoot club guns, just can't have your own.
Here target shooting is pretty much the only reason most people can have a handgun and you must be a member of a club and shoot a minimum of six times per year to maintain your license. If you have more than one class of pistol (classes are air, rim fire, center fire not greater than 9mm/.38 and center fire greater than 9mm/.38 but not greater than .45) you have to do an additional four shoots per class. Example is I own a 9mm, .357, .40S&W and .45ACP so I have two classes and have to shoot ten times a year. I could own ten 9mm handguns but I would only have to shoot six times a year as they are all the same class.
As I said max calibre is 9mm/.38 but you can pay ~$80 and get a High Calibre permit to shoot no greater than .45 for metallic silhouette and/or western action. Depending on the club's range approval (regulated on a state/provincial level) you can shoot your .45ACP in other matches but those shoots will not count as scoring shoots as far as maintaining your license goes as only metallic silhouette and western action are approved disciplines. Also, shooting clubs here, like everywhere, have old farts who don't like anything so even if the range is approved for it the committee can still vote to stop you shooting high calibre pistols in other matches and practicing.
Here's a handy chart that has our firearms license classes, what firearms fall into which class and genuine reasons for getting each one (you must supply a genuine reason when applying and "I want one" or "self defense" will result in a speedy rejection). As you can see most fun stuff is NOT AVAILABLE to Average Joe.
http://www.police.nsw.gov.au/__data/assets/pdf_file/0015/133134/genuine_reasons_table.pdf
Sorry to ramble, was going to give a quick reply but it turned into a bit of a saga
