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Posted: 3/15/2011 2:04:08 PM EDT
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I am in the process of restarting my loads for my .308 rifle. I started out loading my 178gr amax rounds to 2.8" as suggested in my hornady manual.
However, I have been reading and see that it is best to load long and work shorter so pressure doesn't become an issue. I have not seen any pressure signs at this level. My previous load: 178 amax 43 gr varget lc lr brass 2.8" I want to start at 43gr and work up to 44, but I want to move my oal out to 2.81". Will increasing my oal .01" at 43gr cause problems? Then all the rounds following will be loaded in .2gr increments at 2.81" oal. I have read up on the ladder test and would like to do that, but I don't have access to a 300+ yd range except once or twice a month. All testing will be done at 100yds, shooting 5 round groups. I will then load more and test more in depth on the next range day. |
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Where to load a bullet depends on the magazine length, the location of the chamber throat, and the bullet design.
The bullet needs to engage the case neck by 1 to 1.5 diameters, and more doesn't hurt. Magazine length is obvious, the cartridges will need to be single fed if they're too long. The throat is a whole nuther problem and requires some thought. Loading to a jam means starting over from scratch on the load work up, and the bullet's tolerance for starting from a jam. Loading to a jump depends on the bullet's tolerance for the distance. Most likely the loaded cartridge is too long to load in the magazine when loaded out to a small jump (let's say 0.020), but maybe not in a rifle with a custom chamber. Look at the tiny volume you'll add to the case interior by moving the bullet 0.01; it's 0.000 75 cubic inches. Compare that to the volume of the case. However, don't take bullet seating depth lightly with small straight wall cases, the fraction is much larger and alters pressures quickly. |
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I am loading mag length as the max. I have tried putting a bullet seated long in a case with a loose neck tension, then inserted the round and closed the bolt. I read on another forum this is a rough way to measure to where the rifling starts.
Even after moving my bullets out to 2.81" oal, they still have to jump roughly .088" if I have done the test correctly. The reason I decided to change the oal is because most people say it is best to start long and move shorter. As far as max distance, I can shoot to 700yds. I referenced 300 yards because the ladder test seems to do better at 300+ yds. I don't have access to that range as often as I do the 100yd range. |
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Quoted:
I am loading mag length as the max. I have tried putting a bullet seated long in a case with a loose neck tension, then inserted the round and closed the bolt. I read on another forum this is a rough way to measure to where the rifling starts. Even after moving my bullets out to 2.81" oal, they still have to jump roughly .088" if I have done the test correctly. The reason I decided to change the oal is because most people say it is best to start long and move shorter. As far as max distance, I can shoot to 700yds. I referenced 300 yards because the ladder test seems to do better at 300+ yds. I don't have access to that range as often as I do the 100yd range. why would you want to start at a higher pressure and work down? by increasing the oal you increase preasure. seems to me you should work it up. |
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Quoted:
Quoted:
I am loading mag length as the max. I have tried putting a bullet seated long in a case with a loose neck tension, then inserted the round and closed the bolt. I read on another forum this is a rough way to measure to where the rifling starts. Even after moving my bullets out to 2.81" oal, they still have to jump roughly .088" if I have done the test correctly. The reason I decided to change the oal is because most people say it is best to start long and move shorter. As far as max distance, I can shoot to 700yds. I referenced 300 yards because the ladder test seems to do better at 300+ yds. I don't have access to that range as often as I do the 100yd range. why would you want to start at a higher pressure and work down? by increasing the oal you increase preasure. seems to me you should work it up. From what I gather, you are starting at the longer oal and a lower powder charge. Then you work up in powder charge until you find what shoots well. Next you play with oal by moving it shorter and in doing so you can safely assume you will not be increasing pressure. I think the reasoning is so you are not maxxed out on powder with some jump and then decide to increase oal which will increase pressure. I have read that increasing oal can lead to large pressure spikes that were not occuring at the shorter oal. The very bottom of post 1 in this thread is where I got my info: Snipers hide |
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I shoot with a my son who seats to the lands in his match chamber, 2.865. I seat 2.80. Granted we are shooting two completely different loads...
I'm just not seeing much difference out to 800 yards. Past 800 out to 1000 yards.... I am seeing a difference but that could easilily be accounted for by his ability to read wind. |
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