Wow, prepare to drink from a fire hose, cause you're going to get flooded with info from everyone.
First and foremost when reloading, identify the purpose of the cartridge you are going to reload for. I assume because you plan on loading SMKs that you're shooting competition? Or atleast not for hunting, as SMKs are not hunting bullets
If competition is your goal, then you've got your work cut out for you. Unfortunately allaroundhunter nailed it, it's hard as hell to find components right now.
Don't limit yourself, every rifle is different, some may like the 175 SMK some may not. What twist is your rifle? If you have a 1:12 you might want to look at a lighter bullet like the 155 Palma. If you've got the 1:10 a 175 would work pretty well but don't be afraid to experiment.
You NEED a manual, if you haven't already been told that enough.
Ensure that you only load within the manual's specifications. People have a lot of good recipes on the Internet but don't load to the unless they are within a manuals safety limits.
Precision shooting is nothing more than eliminating as many variables as you can, by that there are many things to consider.
- case prep (probably the most important aspect of precision shooting)
Weigh each case (From the same lot) and set aside each piece of brass that weighs any more than say half a grain, to ensure uniformity of volume within the case. Ream the primer pockets, debuted the flash hole, make sure all cases are trimmed to te same length, and chamfer the neck.
Powder- there are many powders out there, and most of them great. It really depends on your rifles appetite. That's where research comes in. When I am looking to develop a load, first I select the bullet for the mission, which seems like you already have. Then I do research on "pet loads" for that bullet in that caliber. There will be a ton of information out there, but look for a lot of repeats, i.e. a ton of people saying the same thing, say, 43.5gr of Varget with the 175SMK works best in theirs. Take that information and look in your manual, and make sure that is within the safety limits of the load. Then you've got something to test. I usually start about 10% of where i see alot of repeat recipes, and load up in increments of .2 grains. Load in groups of 3-5 cartridges per charge. once you have a few groups its time for a range test. But First...
Another consideration:
Seating depth is another consideration when loading, seating depth is how deep you seat the bullet into the case. for precision shooting, send an email to Sierra and see how far off the lands they suggest you seat the bullet. The lands are the beginning grooves of the barrels rifling. more often than not they suggest .030 - .070" off the lands. but consider your internal magazine as well. If you cannot load the ogive of the bullet off the lands, and fit the overall cartridge length within the max length of the internal magazine, that may be an issue for you, if you don't care, and would then rather single load your bullets, then you're good to go. Pick on ONE seating depth for your test (remember, you want your test to only measure ONE variable, in this case it would be the powder)
Once you have your cartridges to test, go to the range, and try em out. if you find one you like, then go with that, if you don't like your results you gotta keep testing. you can change up your variables, bullet, primer, brass, powder, seating depth, whichever.
I wish it were easier, but it took me quite a while to find my pet load.
I didn't adress each variable, because theres books written on that stuff, and too much info for a forum reply.
One last thing to think about when trying to get the tightest MOA group you can get, is understanding that the cartridge is one of three aspects of precision shooting.
Precision shooting is based around
- the equipment (your rifle and optics)
- the cartridge
- the shooter
The Equipment: couple things for your rifle you may want to consider
- The stock - if your stock isn't bedded, do it. it will make a world of difference, whether its pillar bedded, glass bedded, full length aluminum bedded, always better than nothing. Make sure your barrel is floated. and test your trigger tension, find a tension you like, but you definitely don't want it very tight, because that will effect your group quite a bit.
- the barrel - its very important for you to understand all of the physical things that happen as soon as the firing pin hits the primer. understand how temperature effects the whip of your barrel. When testing a load, shoot every shot only once the barrel has cooled.
- The Optics - get yourself some quality optics, plain and simple, if youre shooting out to 500+ you need some good glass. for a beginner, I would suggest the Vortex Diamondback 4-12x 40mm. Its a good scope for a good price. but it isn't the best of quality either. if you have money to spend, look to Leupold.
The Cartridge - We went over a little bit of that, but do your reading and research.
The Shooter - The most important thing for you to tighten your group, is shoot shoot shoot. I would suggest getting something like a bolt action 22LR. Cheap to practice with, accurate, and no recoil to develop bad habits. You can even do that with a pellet gun (set up an indoor range in your garage with a bb gun or pellet gun, remember the goal is trigger time, doesn't matter what kind of projectile)
I think thats more than enough to digest for now, but if you have any questions please let me know.