Best Methodology for Decreasing Group Size?

[goody523]

I know this has probably been covered in bits and pieces elsewhere, but I am trying to get this whole thing straight in my head (I'm new to the reloading game in case you can't figure it out by reading my post).

Let's say, for the sake of simplicity, that you have a custom made gun which is as accurate as humanly possible and it is mounted on a device that takes all shooter error out of the equation. You are trying to work up a load for this gun where accuracy is paramount and speed is secondary. If you were trying to do this in the least number of attempts what is the methodology you would follow. In other words as you are working this down what variables what areas give you the best bang for the buck (or in this case the most accurate bang for the time spent). Based on what I think I understand from reading about a million posts I think it would go something like this (but I'm sure one of you guys who actually knows what they are doing will correct me):

1) Vary powder in .5 grain increments and find tightest group. Once you find best range try .01 increments in this range to get absolute best?

2) If none of these give you good results try a different powder.

3) If none of the powders give better results, try a different bullet (maybe this should actually be #2 - it seems like a lot less of a hassle).

3) Start changing bullet seating depth from start point in increments of X to see if that tightens groups. What is a reasonable number for X?

4) Try different primers?

5) Try different brass? This one really confuses me when I read about guys sorting the brass by weight. I get the concept - if they are all the same length but the weight varies then the internal volume must be variable. So now that I have them weight sorted, what do I do to accomodate the various weights - use slightly more powder in the cases that have a larger internal volume? If so, how the heck do I determine how much more (trial and error I assume). Then I keep some kind of log book with various powder loads for brass of various weights? This seems like it could drive a guy into a padded room quickly.

Am I even remotely correct here?

[skipper]

I wouldn't work up in .5 gr. increments because the steps are too large. I would start somewhere close to minimum and work up in .2 grain increments. Pressures can build fast and you might miss the best load.

I think you have the general idea of how it's done. Pick a powder, bullet, case and primer combination. Look around on the forum and try to find what combinations work for others who shoot the same rifle you do. That might give you an idea of where to start. A lot of peoples rifles seem to like the 39 gr. Sierra BK's with H4895, CCI BR-4 or Rem 7 1/2 primers and Winchester cases. Start loading 5 or so near the minimum charge. Then load the next 5 rounds .2 grains higher and so on until you get to the max. Load your weight sorted cases in order so you don't shoot the lightest and then the heaviest right behind it. That way the difference in volume will be less noticeable. Go out to the range and shoot your rifle starting with the minimum loads and working towards the max. Inspect your fired cases for signs of excessive pressure the whole way through the process. A chronograph would help. A .2 gr. increase should produce a proportional velocity increase. When a .2 gr. increase doesn't result in a proportional velocity increase you should stop.

You might find a load that works with the first combination you try and you might not. If not change powders and try it again. When you find a combination that your rifle likes then you can start changing seating depth, primers, neck tension, etc. to get it fine tuned. Only change one thing at a time otherwise you won't know which change caused things to get better or worse.

[WHISTLEPIG]

goody523, Depending on how many cases you are working with, if you are going to weight sort for shooting groups, get 20 or thirty that are all the same or within 1gr. and keep those for your range cases. You will go nuts sorting 1000 or 1500 cases. Get your load and go with it for the rest of the cases. Your poi will be well within a minuet of squirrel.

I would strongly urge you to not only weight sort your range cases, but also your bullets, and hand weigh each charge.

[goody523]

The sorting idea makes sense to me except I am wondering what you do with all the brass and bullets that don't fit inside the range you set up. Do you break them into groups as well and try to have a load data for each set of ranges. That seems like it could get very difficult to keep track of in a big hurry.

[skipper]

As long as you have enough of each weight to load (5 or however many you shoot for groups) just load them and shoot them together. At 100 yards it is probably not going to make much, if any, difference. They may shoot to a different point of impact at long range but they should still group.

[Hawkeye Joe]

[janneuf]

I read an article on 6mmbr about a guy who shoots 1000 yard groups with a HUNTING rifle from a bipod. This guy shoots 5 shot groups into 2-3" at that range and he stated in the article that he ONLY weighs powder and bullets. He feels weighing cases is a waste of time and effort.

I found this article interesting because he's shooting a 7mm WSM which I own in addition to my 204.

Here's a link if anyone is interested. It's a pretty good article.

http://www.6mmbr.com/gunweek064.html