There are many things you are going to be learning. I would suggest you purchase one of the big name bullet company's reloading manuals printed to help reloaders. Read every bit of the section on how to load rifle cartridges. Attention to detail is paramount when loading these high pressure cartridges.
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A properly set up and sound rifle is very important and should be done before you spend time and money working up loads for your rifle:
BEDDING: The metal should be bedded in the stock so there is no movement. If do not do this you MIGHT still be able to shoot fairly decent groups, but the odds are against you. The concept here is to prevent any shifting of the metal in the stock. If you are using a wooden stock there is an additional issue of changing humidity which can cause the wood to change its shape which can alter point of impact (POI) and also change the size of the groups/accuracy.
TRIGGERJOB: You said you did you own? I would suggest you run a few tests to make sure it is reliable and SAFE.
Cock the trigger and slam the bolt closed as hard as you can. Then pull the trigger recock and repeat multiple times.
Cock the trigger and set the safety, pull the trigger while on safe then push safety off and see if it fires. Repeat
Cock the trigger and slam the recoil pad down hard on the floor to see if you can make it go off.
If any of these cause it to fire the trigger is dangerous and must be readjusted.
SCOPE MOUNTING: Quality bases and rings must be installed so they don't move during recoil. They should be alligned properly so there is no torque applied to the scope tube. In addition it wouldn't hurt to lap the rings to ensure they are alligned and any high/rough spots are removed. This will prevent damage to the scope body or marring of the finish.
ACTION SCREWS: These should be tightenED properly. Some shooters use an inch pound torque wrench. It is difficult to try and tighten consistently by hand. As a general rule tightening as tight as you can do it with one hand on a narrow handled screwdriver is a bit too much. A bit below that torque should work fine IF THE STOCK IS BEDDED. If not bedded even less torque to prevent damage to a wooden stock. You will have to recheck the tightness especially after the first shooting session as things sometimes settle down.
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As for loading refer to the reloading book and your friend's knowledge for setting up the dies and prepping the cases. There is a great deal of information on the web too. It is a matter of consistency. All things like case prep, bullet seating depth, accurate powder measurement need to be the same cartridge to cartridge. You might know this but it must be mentioned: use the same brand brass that has been fired the same number of times. Best way is to start with new brass all from the same lot. As you work you way towards a more accurate round do one change at a time, like adding more powder, and note change. If you do more than one change and things improve or get worse you won't know the cause.
While there are several approaches in working up a load, an easy one is to establish a bullet seating depth first with a dummy round. My approach is to seat the bullet out as far as possible based on the length of the bullet and the end of the magazine. Check with a several dummy rounds to be sure they feed properly and fit. Be sure to fill the magazine and cycle all dummy rounds as if you are hunting and firing multiple shots. (nothing worse than finding out they don't feed from bottom of magazine while hunting) Then be sure the bullet doesn't contact the rifling. An easy way to see if there is contact is to buff the jacket of the bullet with fine steel wool then close the bolt on the dummy round. If the rifling contacts the bullet you will see some small squarish evenly spaced marks which are the rifling. If you see the marks seat the bullet deeper.
Consulting the loading manual start with a powder charge somewhere near the middle of the charge weight. With the 7 rem mag I'd suggest you increase the powder charge in 1/2 grain increments working towards a max charge listed in the book. Shoot three shots with each charge weight at 100 yds off the bench, allowing for cooling of the barrel before firing the next three.
If things work well for you there should be a group or two that are tighter than the rest. Depending on how accurate it is you can stop or go to the next step. If you do find what appears to be a good load you will need to repeat the test several times to prove it truly is consistent and accurate.
If you are still not happy with the accuracy here are two things to try. You could fine tune the powder charge but with this large case it won't make as much a difference as the other manipulation. Change the bullet seating depth in small increments looking for a trend towards a tighter group size. This can be a tedious job if you don't have a seating die with a micrometer top for accurate changes. The idea is to seat the bullet in, lets say, .005" increments deeper into the case.
If you don't have a micrometer style seating style die you can still do this process but it is far more difficult. This really requires some sort of bullet comparator tool like this one:
Sinclair Insert Style Bullet Comparator - Sinclair Intl
Without it you cannot accurately set the seating die/ bullet depth.
Here is how I have done it without a micrometer style seating die: You will be making one dummy round for each seating depth using your bullet comparator to ensure the change is .005" deeper. A factory seating die with its threaded stem is a pain to get just right but it can be done. Once you get the first depth correct load up several cases with the pet powder charge and seat. Lower the seating stem again measuring another dummy round's length to move to the next seating depth increment. Repeat for perhaps 6 increments for testing. If any seating depths show promise go back to the dummy round you made and use it to compare when you go back to adjust the seating die to make more of that depth. Hope this makes sense. Obviously with a micrometer style seating die you would have just written down the number value off the scale and then twisted it to that setting to make more ammo with that seating depth.
So as you can see this reloading can get quite involved. It is attention to details, making small changes and noting results.
I haven't mentioned bench technique which is something you should study. It is all about consistency.
There are even more refined loading details like neck tension, neck sizing instead of full length sizing that are probably best left alone at this time.
Good luck. Research this in detail and get as much information as you can. Let us know your results.
. I am no expert by no means and I was needing some advice and info on what I need to do and know about the rifle and cartrages so that I can have it shooting more accuratly. I have read about guys getting work done to their rifles for better accuracy. What exactly gets done to them. Is the model 70 a rifle that this stuff can be done to and is it worth dioing to?
