400, make yourself at home. This is a great place with very knowledgable folks who in most cases will help you out with getting to your goal.
You questions are not new, or old, for that matter. They are something that just about every new handloader asks someone at sometime if they are looking to improve the consistancy of their loads.
First things first. You haven't mentioned the type of rifle your shooting, straight factory, had a little work done on it, or straight custom. This will also have an effect on your groups as well. Not that a factory rifle can't be loaded to shoot very well, or that just because it is custom it is guaranteed, but some will do better than others.
Your scope can also make a huge difference in groups as well. If it has a bit of parallax in it then you may or may not be repeating the same sight picture from one shot to the next which will cause you to shoot from just a bit off to a whole bunch off. If this happens to be the case just swapping to another scope could bring your groups in somewhat tighter. IF it is a fixed power, then a variable might also help out. Just things to consider.
If you feel that all of the above is good to go and your serious about cutting your group size then you will have to be serious about your loads. This means making sure that the cases are from the same lot, make, length, and even weight if you want to take it that far. For general hunting rounds I have shot several dump truck loads of range brass reloads. They generally group about what your getting. I do not mix them in with cases I have purchased new, they are simply the ones I use when hunting in the real thick stuff or when I want to head out for simple plinking. First off pick yourself up a hundred cases in your choice or brand. I generally use Winchester for most calibers based off the .30-06, however Remington, and Federal are both good as well.
After getting your cases you will want to at least run the expander ball through the necks to be sure they are all concentric. Sometimes they get a little dinged up during shipping. Then go through and measure several, I generally will do 20 to get an overal average of the lengths. Then I will take the shortest one which I set aside, and set my trimmer to at least cut the full face of the case. After setting the lenght on the trimmer, I will trim the whole batch to this length, and debur them all. At this point you have 100 cases ready to load, however there are a few more steps you can do which "may" help you shrink the groups down a smidge. One is to debur the flash hole, another is to uinform the primer pockets, and still another is to weigh out your cases and seperate them into groups. The weighing should be the last thing done. If and when you debur the flash hole you should only use enough pressur to feel the bur being removed. Once it is gone you will feel the cutter moving on top of smooth brass and that is when you stop.
I would also suggest looking at at least one or two other powders. I have shot some nice groups using H-4831, but I have shot a lot more using IMR - 4350, IMR-3031, and now Ramshot Hunter. I have tried close to a dozen more powders as well, but the ones mentioned consistantly groups better and were muchmore consistante over the long run.
I would pick a bullet that you feel should cover anything your likly to hunt. Be it 130, 140, or whatever. I would seat it .020" off the lands to begin with and work up a load which shows promise. Then tweak it in seating a little deeper. This might not be the norm, but I have seen rifle shoot just as tight a group seated back as far as .100" off the lands as right on them. For a hunting load in a repeating rifle you want reliability, and functional feeding. Some of the newer bullet tips will sometims hang in the front of the magazine when chambering a round that is pushing the limit of the magizine length. I would rather have something that will feed smoothly and still shoot around 1" than something that is going to hang up during chambering, and will shoot .5".
As for the primers, I personally use WIN-WLR by and far the most over any other type. They have given consistant ingnition on loads for several calibers for many years. Other swear by this or that, and I have them all on hand. If the Win's just don't get it done then I will switch. I have found that if I don't hit a decent load with a particular powder within a certian load range I will then switch primers. After you have loaded for a while you will find that certian case sizes will generally preform somewhere in the same ball park for powder weights. Like the '06 sized cases, they seem to hit a decent load with medium to slower powders in the 54 - 58gr range. From my experience it really hasn't mattered wether it was necked down or not. The case will hold around 62grs of water roughly and with the mid 50 gr loads your hitting 75% - 95% load density and this generally works out for a nice load.
If I were to recommend a good all around load for this caliber, it would be a 130gr bullet seated over some Ramshot Hunter, either IMR-4350 or H-4350, and lit using a Win-WLR or Fed210.
Good Luck and I hope you can pick through some of this to get to your desired goal.
