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When you are measuring your COAL with a Stoney tool for example, and want to bump off the lands by a certain distance what do you general use for Varmint rifles and hunting rifles? Stoney states to use .020 but Nosler book states to use between .015 to .030. I have been using .020 and as wondering if that is more jump than need for safe reloads? Also bullets vary somewhat so I presume I would need to get some jump to ensure that the reloads are not actually into the lands. I am just wondering if many people start with .010 from the lands?
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Joined: Nov 2011
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Campfire 'Bwana
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Campfire 'Bwana
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Here are the places folks most commonly start.
Just touching. .010 off. Magazine length if more then .010 off.
Which is right for you? I don't know, ask your rifle.
You didn't use logic or reason to get into this opinion, I cannot use logic or reason to get you out of it.
You cannot over estimate the unimportance of nearly everything. John Maxwell
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Campfire Tracker
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I have for a long time started off with the bullet touching, then I jam, then back off 0.010, it 's a hail mary from there.
I use the Stoney point ogive gage with a split neck case.
Bullets should vary very little in the ogive length.
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I start at magazine length or 0.010" off, unless the ogive varies more than that. Hate to say it but cheap bullets may be hard to get close to the lands.
I've found my best accuracy anywhere from 0.020" off to 0.125" off. So much for being close to the lands for best accuracy.
molɔ̀ːn labé skýla
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.010" off is a place to start, but from there you have to experiment. It's just a starting place, every rifle is different and what works for one combo might be wildly different for another. The only way to figure out what your rifle likes is to shoot it. Many rifles need to the bullet jammed into the rifling to shoot their best, but that can be a problem in a hunting rifle because you can pull the bullet out of the case when unloading.
My general rule with hunting rifles is to find the best shooting load I can while still maintaining at least .005" off the lands to keep the bullet from pulling while unloading. This is assuming they'll fit in the magazine, many factory rifles won't let you kiss the lands and still have the rounds fit in the magazine. With a varmint or target rifle I don't care, I'll jam the bullets into the rifling if that's what it takes to make it shoot.
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Reason for asking this is because I did not think people would jam up in the lands as this increases pressure more. And assuming ammunition is more accurate with almost full case or in the upper velocity range and this is where we attempt to find accurate loads, jamming into the lands will increase pressure even more.
I load starting at .020 off the lands and I am thinking maybe I can start at .010 off the lands as I think more ammunition is going to be accurate the closer the bullet is to the lands. As one writer puts it "the time a bullet wandering into the lands can arrive there slightly off which makes it less accurate" but of course each rifle has a distinct preference.
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Reason for asking this is because I did not think people would jam up in the lands as this increases pressure more. And assuming ammunition is more accurate with almost full case or in the upper velocity range and this is where we attempt to find accurate loads, jamming into the lands will increase pressure even more.
That's an assumption that would be argued by many. I've seen plenty of loads that were pretty far from 100% load density that were very accurate, and I haven't found that velocities in the upper velocity range for the cartridge tend to be more accurate. Accuracy is all about harmonics, a load with the widest "node" will usually be more accurate. Fastest and fullest case doesn't mean most accurate, that's an old wives tale that doesn't hold water. If you're going to seat bullets into the lands then you need to work up to it, you don't want to take a full house load worked up with a .030" jump and seat it into the lands, it probably will be a little hot then although the amount of extra pressure seating into the lands generates is often exaggerated. If you work up the load with a chronograph & the bullet kissing the lands you'll likely find it'll take slightly less powder for the same velocity as a jumped bullet. It's not a problem so long as you recognize the limits. Pressure's not a bad thing, too much pressure is.
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Campfire 'Bwana
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Valad, the "at the lands" philosophy originated in the "gimbel" loading method that was prevalent in 1970's benchrest shooters.
As for jamming into the lands, I refuse to do so for the reasons mentioned above. I just have this aversion to a magazine full of powder and a bullet stuck in the lands.
The general rule for safe reloading is start with your longest length fist, and work up your powder charge, then work your AOL shorter. This helps avoid the pressure issues you mentioned above.
In general, I like a full case. That being said, perhaps my most accurate load in the .338 WM is BLC-2 behind a 200gr bullet.
You didn't use logic or reason to get into this opinion, I cannot use logic or reason to get you out of it.
You cannot over estimate the unimportance of nearly everything. John Maxwell
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