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Old February 23, 2013, 10:57 PM   #1
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Bullet seating depth?

So I am just getting into reloading and was wanting to know what most people seat there bullets to. Do most just follow the Max C.O.L. for the given cartridge in the loading data book? Seat up against the lands? Give a .020 "jump space" to the lands? Or does it just depend on what works best for a particular rifle?

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Old February 23, 2013, 11:23 PM   #2
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i personally seat my bullets according to the chamber of the rifle. I always do a chamber cast of my rifles before loading for them, that way i know exactly what the chamber measurments are. i will then start my C.O.L. from those measurments and play with that round till i find what works best in my rifle. Sometimes it might be better to seat the bullet a little farther then the suggested C.O.L. and others not so much.
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Old February 24, 2013, 08:14 AM   #3
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The majority of rifle bullets shoot most accurate whey they seat into the rifling. But they may be too long to feed reliably from the magazine. Some of Berger's bullets seem to shoot most accurate with 10 to 20 thousandths jump to the rifling due to their shape.
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Old February 24, 2013, 08:57 AM   #4
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"So I am just getting into reloading ..."

Strongly suggest you follow the book values for now.

Plenty of variables to tweak later, as your experience base is expanded.
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Old February 24, 2013, 09:26 AM   #5
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A great deal of information on seating depths is discussed at lengh in various gun mags and internet sites. Dan Newberry's OCW method (charge weight and seating depth) is one that comes to mind. I'm new (5 years) to reloading and am just beginning to experiment with various seating depths. I suggest sticking to your reloading manuals recommendations for the time being.
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Old February 24, 2013, 09:26 AM   #6
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My answer to this question has alway been whatever gives you the best results for your particular rifle. Something to experiment with.
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Old February 24, 2013, 10:10 AM   #7
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Seating depth

I feel that seating depth is an extremely under valued component to accuracy improvement. I have to admit that is normally the last adjustment I make but, I do play with seating depth. If you use Barnes bullets they recommend seating depths .030 to .070 off the lands. As far as traditional jacketed bullets, I like .010 to .015 as a starting point. As some have indicated, you're just starting to what. RCBS makes a precision mic to measure just what you're asking for. Some have made their own measurement tool by using an empty round (case and bullet w/o powder or primer). It is very important to remember what you are measuring is the point at which the ogive is contacting the rifiling and backing off from there. So, it is also important to remember that when you switch bullet weights, types, or brands you will have to remeasure for each that you reload. Look what seating depth can do with Barnes bullets.
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Old February 24, 2013, 10:20 AM   #8
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I normally load em up pretty much like 284 does, in that cartridge length is the last thing I fiddle with. I'll use the COAL data from Lyman's 49th for that specific bullet (if that info is available) for the starting loads. If I can't get the info, then I'll measure from bolt face to lands for max length info and decide on a starting length and then vary from there.

And, like already stated, COAL is probably undervalued as an accuracy component by many folks.
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Old February 24, 2013, 10:22 AM   #9
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150 grain E-Tip

Nosler, like Barnes also says that their bullet needs a jump to get it started into the rifling when the primer is struck.... On the other hand, I load the Barnes TTSX 130 grain bullets, only .010 of the lands, and it performs nicely.
The E-tip from nosler, that I'm testing is the 150 grain (.308) for my 30-06, and with these dudes I have them set right at .030 of the lands. My testing and load developement are still inconclusive at this moment.
I use the Comparator from Hornady, and find the measurement of all bullets that I load, for a given rifle, from there I start usually at .010 off the lands and test the powders, until I find the charge weight that it likes, Then I test OAL, until accuracy goes away, and comes back, and goes away, as I lenghten or shorten OAL, at .003 at a time.
I find that this method, For Me, is easy and effective.

Before I had the comparator, I would make up a "dummy" with a bullet and blacken it with a candle then chamber the "dummy", then slide it out and look for rifling marks, and adjust until desired lenght and accuracy are found.
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Last edited by hooligan1; February 24, 2013 at 10:30 AM.
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