Load development with SEATING DEPTH first

[golong]

As I read back through this thread, I wonder if there may be more factual statements based on specific circumstances rather than a single definitive method. Sorting the way I do, I can adjust the L.E. Wilson seater by the amount of variation in the sort and get the same (+/- 0.0005) CBTO. Kind of makes me wonder if the minimal bearing surface needed for a seating stem hits on a more consistent part of a bullet than a larger stem???

Now I don't shoot BR so I am not trying to fit every shot into the same hole, but the only difference between a day when I shoot 3/8 (or greater ) MOA vs. 1/4 is me, not the ammo. Shooting steel, 1/2 is pretty much always good enough. With that, it could be that I am simply not precise enough to see a need to do more than I am doing.

 

[mikecr]

Kind of makes me wonder if the minimal bearing surface needed for a seating stem hits on a more consistent part of a bullet than a larger stem???

I doubt it.
The seating stem contacts lower on bullet noses -for less wedging. This, producing more consistent seating.
If the distance between the seating datum and land contact datum are the same, then CBTO taken to seating datum would be consistent. Until then, simple CBTO is the best we have.

 

[DLT]

This how I've done it for as long as I can remember.
rifle #1 hunting rifle- new to me caliber
rifle #2 target rifle
I take all my loading equipment to the range.

rifle #1 I take one powder and 3 or 4 bullets to the range. All brass been sized and primed prior to going to the range . If the magazine allows I start with my preferred bullet just touching the lands. That's land marks half as long as they are wide. No chance of sticking a bullet and dumping powder.
I take one case, resizing as I go and increase the powder charge until I reach a load that is on the warm side. That load I consider my max pressure load. @200 yds. I start shooting two shot groups while seating the bullet .005" deeper each group. Almost without fail pressure will drop to a point that I have to increase the powder charge. After a series of two shot groups I evaluate performance. Did anything shoot well? Was there a pattern? If the answer was nothing shot well and there was no indication of improved accuracy anywhere in the test I move on to another bullet and start over again.

rifle#2 target rifle, new barrel, caliber/chamber I'm familiar with. One powder and two bullets. I start with an abbreviated seating depth test with a known powder charge and my preferred bullet. I may do the same test with bullet #2 hoping to find a magical combo. I also want to establish my load window which is dependent on temperature. If I tune in cool weather and summer is right around the corner I want to stay on the low side of the window so as not to get ambushed with higher pressures by a temperature spike. What usually happens is while driving to the first match in the spring, about half way there I start thinking I needed another .7 grs. of powder.

I've never subscribed to the idea of tuning by changing the powder charge as my primary tool. Using seating depth changes has always been more predictable and productive for me.

I forgot to add that once I have a load identified either rifle I then confirm with follow up with several groups of anywhere from 3 to five shots and 3-5 groups.

During the rifle #1 test. When you find pressure and start seating your bullet .005 deeper per group and you see your pressure drop. I’m guessing you increase powder to get back to the pressure you seen before and continue on with the test @DaveTooley

Old thread I know

 

[DaveTooley]

During the rifle #1 test. When you find pressure and start seating your bullet .005 deeper per group and you see your pressure drop. I’m guessing you increase powder to get back to the pressure you seen before and continue on with the test @DaveTooley

Old thread I know

That's correct. I do most of my tuning at 200 yds. As the jump increases pressure drops. Sometimes that shows up as vertical on the target. When I see that change, if everything else is at least encouraging I just go up on the powder some and retest. Taking into account current temps and anticipated temps that the rifle will be exposed to.

 

[DLT]

That's correct. I do most of my tuning at 200 yds. As the jump increases pressure drops. Sometimes that shows up as vertical on the target. When I see that change, if everything else is at least encouraging I just go up on the powder some and retest. Taking into account current temps and anticipated temps that the rifle will be exposed to.

Thank you