So I'm familiar with the round robin technique of powder charge selection but what's the best way to incorporate seating depth in the equation. Do you start with round robin in the groove and once you settle on the best OCW then start screwing with seating debth by backing off. Or do you start at say .002 off the lands?
- Thread starter Buckoman
- Start date
Re: Fine Tuning a Load's OCW and Seating Depth
Personally, I start the first round of my OCW with my bullets as long as possible, usually 0.005" off the lands because I like to jump my bullets. VLD shooters would obviously start into the lands. Never, ever start off the lands, and then work your way into the lands.
I call this first seating depth my "zero" position. After determining the best powder charge in round 1, I then decrease seating depth in 0.005" increments in the second round. VLD shooters should consider decreasing seating depth in 0.002" increments.
I also increase my volume to 5-shot groups in the second round.
A third round might then include some 300+ meter confirmation of the final load's long-range performance.
Again, this is just the method that works for me.
<span style="font-weight: bold">Round 1</span> (44.5g chosen)
<span style="font-weight: bold">Round 2</span> (-0.015" from "zero" chosen)
Personally, I start the first round of my OCW with my bullets as long as possible, usually 0.005" off the lands because I like to jump my bullets. VLD shooters would obviously start into the lands. Never, ever start off the lands, and then work your way into the lands.
I call this first seating depth my "zero" position. After determining the best powder charge in round 1, I then decrease seating depth in 0.005" increments in the second round. VLD shooters should consider decreasing seating depth in 0.002" increments.
I also increase my volume to 5-shot groups in the second round.
A third round might then include some 300+ meter confirmation of the final load's long-range performance.
Again, this is just the method that works for me.
<span style="font-weight: bold">Round 1</span> (44.5g chosen)
<span style="font-weight: bold">Round 2</span> (-0.015" from "zero" chosen)
Re: Fine Tuning a Load's OCW and Seating Depth
wow, that is some very good info. Thanks a bunch.
wow, that is some very good info. Thanks a bunch.
Re: Fine Tuning a Load's OCW and Seating Depth
Glock24, why was 44.5gr chosen? It appeared to have worked out for you, but it doesn't look to have the least amount of vertical dispersion.
Glock24, why was 44.5gr chosen? It appeared to have worked out for you, but it doesn't look to have the least amount of vertical dispersion.
Re: Fine Tuning a Load's OCW and Seating Depth
OCW isn't necessarily about choosing the least amount of vertical dispersion in a particular test group, but the point where the least amount of POI shift occurs. Sometimes the two situation coincide, but thats just happy circumstance
@ 100yds sometimes its hard to accurately triangulate the actual center of the group just by eye-ballin' it... which is when I resort to scanning targets into On Target Precision Calculator (camera pics work as well if you have a reference object in the image).
OCW isn't necessarily about choosing the least amount of vertical dispersion in a particular test group, but the point where the least amount of POI shift occurs. Sometimes the two situation coincide, but thats just happy circumstance
@ 100yds sometimes its hard to accurately triangulate the actual center of the group just by eye-ballin' it... which is when I resort to scanning targets into On Target Precision Calculator (camera pics work as well if you have a reference object in the image).
Re: Fine Tuning a Load's OCW and Seating Depth
glock24, I agree with your OCW assessment above, but would challenge your seating depth choice.
I would have chosen the 10 thous off as my load. Then, as your throat erodes, you at least know that you are good for another 5 thous of erosion. If you choose 15 thous off, you dont have data on 20 thous to see if still in the node.
What were your thoughts on choosing 15 thous for your OAL?
glock24, I agree with your OCW assessment above, but would challenge your seating depth choice.
I would have chosen the 10 thous off as my load. Then, as your throat erodes, you at least know that you are good for another 5 thous of erosion. If you choose 15 thous off, you dont have data on 20 thous to see if still in the node.
What were your thoughts on choosing 15 thous for your OAL?
Re: Fine Tuning a Load's OCW and Seating Depth
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kyreloader</div><div class="ubbcode-body">glock24, I agree with your OCW assessment above, but would challenge your seating depth choice.
I would have chosen the 10 thous off as my load. Then, as your throat erodes, you at least know that you are good for another 5 thous of erosion. If you choose 15 thous off, you dont have data on 20 thous to see if still in the node.
What were your thoughts on choosing 15 thous for your OAL? </div></div>
You make a good point. My decision was based on trying to stay far away from the 0.005" depth where my groups aren't optimal. I see now that I may have went too far the other way. I'll keep throat erosion in mind as I reload additional rounds on an older barrel.
Thanks
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kyreloader</div><div class="ubbcode-body">glock24, I agree with your OCW assessment above, but would challenge your seating depth choice.
I would have chosen the 10 thous off as my load. Then, as your throat erodes, you at least know that you are good for another 5 thous of erosion. If you choose 15 thous off, you dont have data on 20 thous to see if still in the node.
What were your thoughts on choosing 15 thous for your OAL? </div></div>
You make a good point. My decision was based on trying to stay far away from the 0.005" depth where my groups aren't optimal. I see now that I may have went too far the other way. I'll keep throat erosion in mind as I reload additional rounds on an older barrel.
Thanks
Re: Fine Tuning a Load's OCW and Seating Depth
I start my OCW exercise at the recommended seating depth and work from there. In your own example you moved back from your "0" at .005" from the lands. I'll wager your .015" from your zero is much closer to the bullet manufacturers recommended seating depth than your zero.
I start my OCW exercise at the recommended seating depth and work from there. In your own example you moved back from your "0" at .005" from the lands. I'll wager your .015" from your zero is much closer to the bullet manufacturers recommended seating depth than your zero.
