Assembled Stainless Steel Guide Rod for Ruger® Security-380® Compact Pistols

You would go up in rate over stock for more recoil control.

Bullet weight isn't the factor, it is the pressure pushing it. If your going to the highest rate on the 380 it should be only for feeding the highest pressure ammo, like +P, as most will not cycle well with the higher rate. 380 is sub sonic normally and the stock rate is best for practice ammo that will be just inside sami specs, higher grade ammo will be in the middle to high for standard pressure and have a higher FPS. You will want the stock rate spring assembly for practice ammo unless you load your own to the higher pressure ranges.

The higher rate spring will have more holding force at battery yes. I've never seen on that was weak at battery in these though as they are tilting action not blow back. You're having misfires with off the shelf factory loaded ammo across multiple brands?

The highest rate we offer would be your best option for the very high pressure load range of that sort of ammo. I would reach out to Ruger to confirm the chamber will handle the extreme range of pressure some of the higher end custom defensive ammo runs at.

Going up to the 10% with standard pressure or high pressure ammo will work fine. The low pressure loads that just barely make it into pressure minimum range will not cycle well. The 20% increase is for the higher pressure ammo out there.