Adjusting seating depth?

devildoc · #1 03-02-2006, 03:30 PM

In the past I've always just used a stoney point bullet comparator to discern max seating depth and seat a little bit back from that (unless that is too long for the magazine). However after reading this forum I'd like to try playing with my seating depth a little. So my question is, what procedure do some of you pros use to adjust your seating depth? What increments do you test etc.

Ol'Gator · #2 03-02-2006, 04:03 PM

I know you've ask for pros opinion but I'm gonna put in my $.02 anyway. I've been using the same stoney point tools to determine the oal that just touches the lands. Once I feel like I have the best powder load and only then do I start backing away from the lands. I move in 4 thousandths increments but couldn't tell you why I chose this amount. I like to start off touching or very near so I only have one way to travel for my testing. Sometimes (with some guns) seating depth isn't as critical as you might imagine. I know some find the sweet spot moving into the lands. That's what makes this all so interesting.

BountyHunter · #3 03-03-2006, 02:55 PM

IF mag concerns drive your OAL. Start at mag max OAL and come off .010 increments and see what the groups do.

You should hit a point where they tighten then loosen up. In that area you might reshoot at .005 increments if they are not tight enough for you.

Generally most mags throats move about .003-.005 or more with every 100 rds fired, so to maintain same ogive-lands relationship, your seating depth has to move forward the amount of the throat erosion.

The sinclair intl tool, Sinclair Seating Depth Tool, #09-400 cost is $28.95 is the easiest to use for measuring throat erosion and location of the lands. www.sinclairintl.com

BH

devildoc · #4 03-03-2006, 05:01 PM

I'm sorry, I missed what you were saying at the end there Bounty, Are you saying the magazine's or the barrel's throat will erode every 100rounds. I'm assuming you mis-typed, because I was unaware a magazine had a throat.

relabbe · #5 03-03-2006, 06:23 PM

I guessed Bountyhunter is referring to Magnum rifles, not magazine.

Eaglet · #6 03-03-2006, 10:28 PM

Yes! That's exactly what he's saying.

devildoc · #7 03-04-2006, 08:20 AM

Ahhhh, well that makes a little more sense.