Hi Mac,
The .300 Win Mag is a belted case and personally I prefer a none belted case...which when you learn re-loading you will see why...you get much better case life and accuracy from none belted cases if looked after properly...but this is accuracy at extreme ranges...after weighing and batching cases...testing them with water for inner volume capacity and wanting the re-loaded rounds to be "clones" of each other. For factory ammo...it makes no odds...but saying it simple...you can seat a round which is none belted off the shoulder...just use a neck die and fully re-sized die after say every 5 uses and use them 15 times max if they are good brass. A belted case needs the dies tweaking carefully if you need to fully re-size to still have the round seated off the shoulder and not off the belt. They are tricky for extreme range and are not used by the worlds top shooters for this reason...they were designed for safe re-loading on dangerous game...ideally in a double rifle...so it is "horses for courses"...you can get belted cases to extract well if they are the rimmed type of rounds for double rifle use. If you are using them in a bolt action follow Tolly's advice and get a Mauser Action with a controlled feed bolt. They dont work well in large cartridges with a push feed system.
If you are thinking of an option for a second rifle for long range shooting which you can use in F Class comps which can be shot economically...as the .338 LM is expensive and whilst legal as a calibre in the US for F Class is not legal for international use...I would look at a straight .284 Winchester...it is a 7mm case and you can shoot it cheap with Winchester brass or competitively using Lapua 6.5 x 284 brass necked up to 7mm. Use either Berger 180 grain HPBT's or the sierra 175 grain HPBT...Bergers are better but more expensive.
This round won the US Nationals in 2008...so nothing is better in my opinion.
It is a custom round and would take a custom barrel but the round count is good with this round and you will have a platform to build skill on right to the very top. Bartlein barrels are near you in Wisconsin or atleast are not at the other end of the country...Tracy there is the guy to speak to...Kelbly's is in Ohio from memory and they can do an action...the Stolle Panda is good...a BAT action is better...they are single shot bench rest actions...a rifle like this costs a bit but then it is there for the rest of your life...and you can have multiple barrel/calibre options by simply changing the barrel. Single shot is no disadvantage when you hit what you aim at.... A lighter profile varmint barrel is a great all rounder...you can carry it and still compete...26 inches would be my choice as an all rounder and a half inch at the mussle on a straight taper. Similar spec's to many sniping rifles. Hunting with it is fine as it is not too heavy...
The Arktis jacket is used by some of our Police guys in Black....not my choice...here is a link to a company which makes jackets in Ventile...I went for a triple layer Ventile jacket which was custom built in forest green...it is a version of their Artic Smock with a full length zip and whilst not cheap gives 25 years of use and not 2 to 5. You want press studs on the pockets not velcro as it is too noisy...and ask for some spare studs which can be fitted at home by anyone...they are the weakest issue...but velcro really "rips" when out hunting at dawn and dusk. Mine cost £245 but is well worth it...I got some inside pockets done and a shoulder pen pocket...if you're interested they will remember my order spec's.
http://www.west-winds.co.uk/ventilejackets.htmThe sallopettes in the same colour are also great...if you wear a rucksack/deer sack the sallopettes stop trousers falling down around your backside when carrying heavy weights or when crawling...particularly the latter...they also keep your kidneys warm and over the years prevent a "lower back" arthritic complaint...again they are'nt cheap but worth it.
Forget rear back pockets...a pain in a high seat and if wearing webbing...plus if you use them the slinging of your rifle is difficult as is using a drag bag for the rifle for range use with your gear in it as you cannot carry it like a ruck sack easily...use webbing for heavy gear if need be. I have belt webbing or a molle vest which I can attach a Ghillie cape to...and kit the belt kit/vest out to suit me....the vest can take a Camel Back for water and takes my shooting sticks and my other gear. But this set up is more military than hunting.
However here is the web site for getting a good Ghillie cape without the hours needed to make your own...this lite weight poncho is best but you need to cut away around the bottom at the front for leg movement...do little bits after testing but you will need a fair bit off this to be comfortable walking...check out the other capes for an idea of what I mean. It can fit over a small rucksack etc and can be quicly removed and put in the sack so you don't scare the sheeple...makes a cammo jacket look like a hi-visibility vest...I use this with my Ventile gear so I can take it off and go in the pub for a pint and leave my rucksack etc in the corner or in the car...go light weight on this stuff...the heavy is "heavy" when wet. Hood up and simply crouched down on one knee and I have had foxes and deer come within feet of me if I have the wind right and have called them in.
http://www.ghilliesuits.com/paintballghillieponcho-1.aspx 
