Well, long range shooting and hand loading is a whole different game than loading for hunting or for ranges with 200-300 meter target butts.
You have given us a vague idea of what you are trying to do.
The first thing to consider is whether or not your rifles are capable of DECENT long range accuracy.
The 22-250, IMHO is a fantastic cartridge but if you want to use it at extended ranges, for most people anything over 300m is considered to be extended, then the rifle needs to be purchased or built to shoot heavier very low drag bullets. This means at least a 1-8 twist rate for the rifling in your bore. It also means a special, tight chamber and tight tolerances on the necks. Then you will need special dies with interchangeable neck sizing rings and an arbor press. A regular press will not cut it when it comes to competition. Yes, there are always exceptions but they are very few and far between.
When it comes to long range shooting, about the only thing that is interchangeable is the arbor press.
9mm can be done on just about any decent press. If you are going to shoot several hundred rounds per week, a progressive press is your best bet. Unless you have a special pistol built for accuracy standards are a lot looser.
The 308 Win, is a very good long range cartridge/rifle combination.
Today's off the shelf offerings are very good and often good enough to be competition rifles. The trick is to pick one out of the herd. You may have to go through several or maybe the first one you buy will be a winner. Again, you would be further ahead purchasing a rifle made by the manufacturer of your choice and build a rifle to suit your purpose. These days with CNC produced components just about any of the majors produce exceptional receivers. Trigger groups mostly leave something to be desired.
Again, special dies with interchangeable necks are needed.
On top of this, you will need a tool to turn the necks of your cases so that there is around .002in difference between the ID of the chamber and OD of the neck. It's a lot easier than it sounds and once you're set up for it, not tedious at all.
I don't think, from the sounds of your post, that your experience in long range shooting is lacking.
If the option is open for you, contact some people in your area that are willing to be mentors. I'm not talking about a bud from the local suds palace that has preconceived ideas based on video games and movies.
You need to go to a local club or shop that deals with people that are interested in wringing out as much accuracy as they possibly can from their firearms.
Once you have gone so far as to search out such people they will check you out to see if you are really serious or not. If you pass muster and don't come off like you're playing a game of Seal Team Six they will take you under their wing and teach you proper shooting techniques so that you can be as good as your rifle.
The group of long range precision shooter is small. Most people can't afford the rifles and the kit that goes with them. Same goes for ammunition components.
You really need to do some homework and figure out the style of long range shooting you want to get into as well as the ranges you want to shoot.
IMHO, the $300 you speak of is a drop in the proverbial bucket but it is a good start if you have a rifle that warrants the expense.
Contrary to a lot of popular conceptions, not all rifles are capable of good accuracy. If you're going to compete or even hunt critters such as coyotes, your rifle has to be capable of 1/4 moa or less right out to the ranges you wish to shoot. REMEMBER, the average coyote is from 4-6 in from the top of its spine to the bottom of its sternum. Any gust of wind between you and that coyote at 400 yards is enough to drift your bullet into the ether and either wound or miss your animal.
Competition is even more critical.
I don't want to dissuade you from this form of shooting but it has been my experience that for most people it is more wannabe than it is a realistic endeavor. Be prepared to spend a lot of money and hours of your time loading, tweaking and developing loads for each rifle. Then of course, don't forget the scope. Be prepared to spend more money on a scope capable of eliminating the parallax out to the ranges you wish to shoot than the cost of the rifle and other components combined.
Are you sure you want to go to these lengths??? A lot of clubs and even buddy circles have a lot of fun with off the shelf rifles without having to take out a mortgage and use up almost all of your available spare time.
If you're married and your spouse refuses to or can't understand your passion, you will either get a divorce or quit before you really get into it.
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