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Posted: 4/16/2009 2:36:17 PM EDT
| Couldn't I seat a bullet almost all the way out of the case, then feed it into the rifle and have the combination of the bolt and the lands push the bullet to the exact COL? And if not, why? Would it damage the lands first? |
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Quoted:
Couldn't I seat a bullet almost all the way out of the case, then feed it into the rifle and have the combination of the bolt and the lands push the bullet to the exact COL? And if not, why? Would it damage the lands first? You could do that ... some precision shooters do it. But the thing is ... you will want to pull it back just a little bit ..... and if its not a match chamber or such you might be longer than what will fit in the magazine. |
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Close, but you'll end up with a measurement that's too long, because the bullet will soft seat somewhat into the rifling rather than stopping right when it begins.
If you're trying to measure where the lands are for a particular bullet, you can seat the bullet long and stuff the cartridge into the chamber with your thumb. If it falls out from gravity alone, it's not touching the rifling. If you need to use a thumbnail or tool to get it out, you're in the lands (seat deeper by 0.005" and repeat). Accurate and repeatable––moreso than the RCBS Precision Case Mic by a long ways. As the previous poster pointed out, most factory barrels will be waaaaaaaay out there. |
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Quoted:
Close, but you'll end up with a measurement that's too long, because the bullet will soft seat somewhat into the rifling rather than stopping right when it begins. If you're trying to measure where the lands are for a particular bullet, you can seat the bullet long and stuff the cartridge into the chamber with your thumb. If it falls out from gravity alone, it's not touching the rifling. If you need to use a thumbnail or tool to get it out, you're in the lands (seat deeper by 0.005" and repeat). Accurate and repeatable––moreso than the RCBS Precision Case Mic by a long ways. As the previous poster pointed out, most factory barrels will be waaaaaaaay out there. I used a fired case since it lightly held the bullet. I was able to chamber the round and extract it without the rifling engageing the bullet and pulling it from the case. |
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Quoted:
Couldn't I seat a bullet almost all the way out of the case, then feed it into the rifle and have the combination of the bolt and the lands push the bullet to the exact COL? And if not, why? Would it damage the lands first? What's your goal? Seating to hard contact with the lands, or measurement of cartridge head to ogive length? A copper jacketed lead core bullet will not hurt the barrel. If you're doing this to seat in intimate contact with rifling lands in pursuit of accuracy, first make sure you have a bullet that works okay from the jam. Be sure to back off on the starting charge; this is no place to screw around with loading maximum charges to start. If you're doing this to measure the length of the chamber throat, the split neck method will work if the bullet doesn't stick in the lands. A better method is to size just a quarter of the length of the neck, or thereabouts, just enough to hold the bullet so it doesn't stick in the lands, but still easy enough to push while closing the bolt. The bolt should be disassembled for this method so the ejector or extractor can't put a side loading bias on the case that causes it to bear against one side of the chamber. |
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