Dumb question about seating depth

Ryan Venema

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Jun 7, 2018
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I am new to reloading rifle cartridges. I am currently doing my first reloading for load development and have a question about seating depth. I am loading 6.5 creedmoor, Hornady brass (trimmed to 1.92"), Hornady SST 140 Grain. I did the dummy load to measure my lands at 2.81" OAL, and am backing off .02 to 2.79" OAL. My question is when I seat to this depth the knurled ring on the Bullet is not below the shell casing. Is this ok? I can't remember ever loading a round that has this showing, but I am well within the Cartridge OAL listed by Nosler.

Thank you
 

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gohring3006

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It can happen when you do as you did, and loaded towards the lands. I will add, I like at least 80% of the caliber size of the bullet in the neck not counting the boat tail. Some like whatever the caliber is, that much of the bearing surface should be seated in the neck. I like at least 80%.
 

gohring3006

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Not counting boat tail I have .43” seated which if I understand you is well above the .264 of the caliber. And you like at least .211” (in this case)
I wasn’t to worried about your bullet/case seating, I know that 140 grain bullets in 6.5 are fairly long. I seen your pics and was confident you were fine in that regard. That’s why my first response was a short one. But I thought my second response was relevant to the topic.
 
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AZShooter

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The cannulure (knurled zone) is used for crimping the cartridge neck on the bullet. I am now wondering about ANY 6.5 that would need to be crimped but that is another thread.

Seat where you desire within certain parameters. Not so deep into the lands that should you have to remove the loaded round without firing it would leave the bullet in the barrel and spill powder. Or if you desire a repeater not so long that wouldn't fit and feed properly from the magazine. Or with a short bullet not enough contact with the cartridge neck.

What you are doing is fine. Work up your powder charge for best accuracy and you should be good.
 

Ryan Venema

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Thank you guys a lot. This has been a Fun but new, adventure. It is in a bolt gun so magazine length isn’t an issue. I am probably doing over kill but I am starting at the lowest powder charge listed and the going up to the max powder, by .2 grains looking for nodes and pressure signs.
 

LaHunter

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If you are actually measuring OAL (over all length from the base of the brass to the bullet tip), you will have a lot of variance in your 'real' distance from the lands. You need to be measuring CBTO (cartridge base to ogive). The Hornady Lock n Load comparator tool kit works well. The CBTO is the useful measurement. OAL is primarily useful to determine if cartridge will fit the magazine. All bullets, and especially poly tipped bullets will vary in OAL.
 

Ryan Venema

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Will I still have that much variance if I trimmed and sized my brass I tested OAL with, then used trimmed and sized to same specs for my loads? I know it will change with new bullets, but I don’t see where my variance will come from in this scenario.
 

LaHunter

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The variance comes when you base your measurement from the bullet tip. Cartridge Base To Ogive (CBTO) is the useful measurement when working on seating depth. Trimming your brass has nothing to do with either measurement, OAL or CBTO. The tip of the bullet is not making contact with your barrel, the bearing surface of the bullet is. The ogive reference point of the bullet is near the bearing surface. Since you are new, I would suggest getting some manuals.
 

RT2506

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What LaHunter is trying to say is the bullet tips are not all the same. Even the plastic tips do very in length. If you measure from base of case to tip of the bullet and you make every bullet measure the same you will have a difference in how far away from the lands your bullet ogive is thus you will have inconsistent jump to the lands. If you use a comparator and measure your rounds from the base of the case to the ogive on the bullet then you are getting a constant uniform jump of the ogive on the bullet to the lands. As for the cannular on the bullet and why it is there many people when shooting semi auto rifles like in AR10s in 6.5 Creedmoor do seat their bullets deep to work through the magazine and crimp the case mouth into the cannular to keep the bullet from maybe being pushed back into the case some with the violent slam bang operation of the action.
 

Ryan Venema

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This is why I love this site. You guys are a wealth of information. RT2506, that makes sense. I have some manuals ordered just waiting on delivery. Thank you all again very much.
 

jes10x1

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Jun 21, 2007
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I would strongly recommend either the Forster or Ho4nady too for OAL to ogive. I found that the seating depth is really important to accuracy during a test done during a high power class conducted by Jim Owens. My particular AR shot best with a .040 off the lands seating depth. Wi5h 5hat depth it would Shiite about 1” at the 600 line. Better than I can do! But...closer is not always better!
 

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