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Old April 7, 2013, 03:56 PM   #1
ndking1126
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A double check on seating depth.. for my safety

I'm new to reloading and have gotten to deciding on seating depth and I really don't have a warm-fuzzy about it right now. Given the safety factor (touching lands=greater pressure), I'd appreciate a little feedback before I go any further.

Today I cut a 30-06 case, put a 165gr Nosler BT in it and closed the bolt softly, open it softly and try to catch the round as it ejected. Starting a COAL of about 3.65", it would push the bullet in consistently to COAL of 3.477-3.479".

Here is the case I was using:


The bullet sat in the case firmly enough that it didn't move at just any bump, but it did take some effort to pull it out or push it further. I don't see any noticeable marks on the bullet from the lands. I tried pushing the bullet in even farther, and the pressure seems to be even to get it to go basically all the way into the cartridge.

The length is longer than I was expecting. I know throats vary.. that's just higher than I thought. The upside is that the COAL was very consistent.

I measured the OTS rounds I have. They have a COAL of 3.22" (165 Rem Accutip) and 3.29" (168 BH A-Max). The Accutips shoot worse than CoreLocks and the BH is OK. Most accurate I've ever shot was 168 Federal GMM, but I don't any to measure right now.

I know you have to experiment to find the best seating depth for your exact rifle, but I was planning on going with .020" off the lands, as that seems like a pretty common starting point. If that's advisable, that means I would need a COAL of 3.457".

I have an older Remington 700 ADL in .30-06. Am I on the right track? Thanks!
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Old April 7, 2013, 04:08 PM   #2
Brian Pfleuger
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Also try removing the bolt, pushing the case firmly into the chamber by hand and gently pushing it out with a cleaning rod from the muzzle. That ensures that the bullet isn't sticking in the rifling. If you get the same measurement both ways, you can be confident that it's correct.

The next question is if rounds that long will fit in your magazine, or if you care that they do/don't.

Nothing wrong with 0.020 but nothing special about it either. If that number is what you want to use, start at minimum starting loads and work up in 0.7-1.0% increments.
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Old April 7, 2013, 04:24 PM   #3
ndking1126
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Great idea, thanks. I did that twice and it came out to 3.466" both times. I'll assume that's the right number since its shorter and it just seems like it would be a more reliable measurement. The round fell back out of the chamber with out any pressure on the cleaning rod (literally just about touching it) so I have no problem trusting the number.

Brian, is there a seating depth you would recommend I start with? I'm not at all set on .020" off, that's just what I've read. I haven't even checked to see if that will fit in my internal mag. I could just as easily drop that to a COAL of 3.4" just to stay on the safe side. That would still be significantly closer than the commercial ammo I'm shooting.
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Last edited by ndking1126; April 7, 2013 at 04:42 PM.
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Old April 7, 2013, 04:44 PM   #4
Brian Pfleuger
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Trouble is, if the case is sticking slightly in the chamber, the bullet may be pushing back into the case before the case starts to move.

Edit:

I see you were editing while I was replying. It sounds like you have a good number to start from. Give it a try and watch for pressure signs.

Here's another method to try....

Chamber the dummy round as you did originally. Slide your cleaning rod, with a flat tip on it, into the barrel until it touches the bullet. Scratch it with a razor blade, held flat against the crown. Now eject the round, close the bolt and insert the rod until it touches the breachface. Mark it again with the razor. That should give you a good number too.

The discrepancies you're seeing are why I greatly prefer the Hornady OAL tool.

As far as the off-set from the rifling, nothing wrong with 0.020, it's just that there's really no "correct" number. What your gun "likes" will change depending on the bullet and powder, or it may not change. Most of my guns seem to care more about consistency that a specific number.
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Old April 7, 2013, 05:11 PM   #5
ndking1126
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I appreciate the feedback. I should be able to get to the range next weekend and try out my first set of rounds I loaded. It'll be fun! I'll let you know if anything interesting happens.
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