Thread: Seating depth variance between powders

Question for the knowledgeable, if I have developed a load that shoots very well is that likely to be the optimum COAL/CBTO regardless of powder for that rifle?

If I just change powders would you find the optimum charge weight with the new powder at the previous load COAL and write off the power if you don't find accuracy or would you take the best charge weight and tweak the seating depth to try and find accuracy?

Rifle in question shoots AR2208 load into 0.5MOA but have some RL17 to try, normal story looking for a bit more speed!

Everything I've read (and my own anecdotal experience for whatever that's worth) suggests that once you've found the absolute ideal seating depth, it's good to use across multiple powders and charge weights - but depending on how you got to the length that you're working with currently, it may not be THE best seating depth.

A quick workup to find where your pressure limit is, followed by a seating depth test (after you've found what appears to be a nice stable velocity "node" with the right powder+charge weight+primer combo) seems to be the quickest way to settle on a load that I've found.

The criticality of doing a seating depth test goes up and up, the more the bullet leans towards being a VLD style bullet (secant ogives), and the size of the adjustments you need to make to find that depth goes down.

In my limited experience once I have found the seating depth, I keep it there. As an example my 7RM with 162ELDX likes them at 30thou jump. This worked with IMR4831 and Rel 23 but no matter what seating depth I used it would not shoot with 2217. This is assuming you maintain the same projectile. My experience is limited though so others may elaborate more.