rnbra-shooter
CGN Ultra frequent flyer
- Location
- New Brunswick
Bolivar - If your SD (Standard Deviation) is more than 15fps or your ES (Extreme Spread) is more than 45fps, it is probably hurting your 1000y results and it would be worth trying to do better. (interesting aside - a nice rule of thumb is that the ES of a group is often about 3X its SD).
For iron sights & sling "Target Rifle" shooting, getting your SD down to 10fps (ES 30fps or less) is good enough to win a national or world championship match.
For F-Class shooting you should certainly try to get get SD down to 10fps, and it might help you a bit to do even a bit better than this.
Weight sorting cases isn't that hard, with a digital scale. Before you get too bent out of shape weighing a thousand pieces of brass, try weighing out a hundred or two hundred. If it were a .308 I would suggest putting them into 1-grain "bins" but since it is a .223 I will suggest putting them into 0.5 grain "bins".
You will find that you will have two or three cases that are clear "outliers", being considerably heavier or lighter than all the rest. Set them aside and write their weight on them with a Sharpie. When you have a really good load developed (low SD), after you have shot 5-10 shots with your weight-sorted brass over a chronohraph and therefore know how fast they are going that day, try shooting a few shots loaded with your "outlier" brass. See how much higher or lower than mean velocity you get (what you really want to see is how many SDs fast or slow they are). That will give you a pretty good idea of how many fps difference a grain or two of case weight will give you. If you don't have any decently-wide outliers in your brass you could try a military case (they tend to be *much* heavier).
Most people will weight-sort their brass into 0.1 grain "bins", because everybody has a digital scale that reads to 0.1 grains. That certainly causes no harm, but I am pretty sure that this is probably a finer tolerance than matters.
FWIW years ago when we shot military issue ammo, I found that an IVI military case (.308) would hit about 2 MOA higher than a Winchester commercial case (this is the the same charge of powder, shooting a 155 grain bullet out of a 30" barrel). The IVI case was (IIRC) about 20 grains heavier than the 165 grain Winchester case. So given that a case 20 grains heavier hit about 2 MOA higher at 1000 yards you can see why I suggest that 1-grain "bins" are good enough and that 0.1 grain bins are probably a time-waster.
For iron sights & sling "Target Rifle" shooting, getting your SD down to 10fps (ES 30fps or less) is good enough to win a national or world championship match.
For F-Class shooting you should certainly try to get get SD down to 10fps, and it might help you a bit to do even a bit better than this.
Weight sorting cases isn't that hard, with a digital scale. Before you get too bent out of shape weighing a thousand pieces of brass, try weighing out a hundred or two hundred. If it were a .308 I would suggest putting them into 1-grain "bins" but since it is a .223 I will suggest putting them into 0.5 grain "bins".
You will find that you will have two or three cases that are clear "outliers", being considerably heavier or lighter than all the rest. Set them aside and write their weight on them with a Sharpie. When you have a really good load developed (low SD), after you have shot 5-10 shots with your weight-sorted brass over a chronohraph and therefore know how fast they are going that day, try shooting a few shots loaded with your "outlier" brass. See how much higher or lower than mean velocity you get (what you really want to see is how many SDs fast or slow they are). That will give you a pretty good idea of how many fps difference a grain or two of case weight will give you. If you don't have any decently-wide outliers in your brass you could try a military case (they tend to be *much* heavier).
Most people will weight-sort their brass into 0.1 grain "bins", because everybody has a digital scale that reads to 0.1 grains. That certainly causes no harm, but I am pretty sure that this is probably a finer tolerance than matters.
FWIW years ago when we shot military issue ammo, I found that an IVI military case (.308) would hit about 2 MOA higher than a Winchester commercial case (this is the the same charge of powder, shooting a 155 grain bullet out of a 30" barrel). The IVI case was (IIRC) about 20 grains heavier than the 165 grain Winchester case. So given that a case 20 grains heavier hit about 2 MOA higher at 1000 yards you can see why I suggest that 1-grain "bins" are good enough and that 0.1 grain bins are probably a time-waster.
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