ROA Nipple Problem

Awhile back I posted a problem about one of my ROA's that was having lots of misfires.
Finally got around to trying some things.

Pushing the Remington #10's on with a wood rod did not help, still had misfires.

Then I swapped nipples with my other ROA and now it works fine. So it is the nipples.

The nipples that are a problem are not like my other two ROA's, the ones that work are stainless. The ones that don't work are steel and darker in appearance.

I used a micrometer and the overall length of both are exactly the same. Only thing that seemed to mic different was the very tip, the stainless ones are slightly smaller around only at the very tip by about 2/1000 (.163 versus .161). The base near the hex is the same. My guess is the steel nipples would work better with #11's. If course I've stocked up on #10's.

I could get the Treso nipples but they use a different wrench (thought I saw some that also had the hex but can't find them now)? On my older ROA's with the stainless nipples they work fine and never plug up with fouling. I've read that the Treso nipples have a smaller flash hole, and gives a hotter ignition and less blow back. But if it plugs off and makes the cap more difficult to come off after firing I'm not sure it's worth it. Not sure what size cap these take, most say CCI #11's?

I see on Ebay that "Uncle Mikes" has stainless ROA nipples for sale. Wonder if these would identical as far as using #10 caps?

Other option is to take to try and modify the steel nipples with sanding a lapping but probably best to just save them as is.

The problem is that it takes several hits on the same cap to get the cap to ignite, even if they are pressed on with a wood rod. Not the other type of misfire where the cap ignites but the powder doesn't. The slightly smaller diameter of the SS nipples allows the caps to fire without a problem, at least that's what I assume.
Thanks for everyone's input on this, I'll probably stick with a hex head now that I know I have more options.

I am using #10 Remington nipples. I have two other ROA's that don't have a problem with at all (they are older units with SS nipples). The ROA I'm having problems with is a "newer" highly polished SS with fixed sights. For some reason it has steel nipples (not SS), they are hex head, but perhaps they are not original, or did Ruger change to steel later?

As I said, when I mic'ed them, the steel ones are .002 larger at the tip only. This must be keeping the cap from sliding down enough to allow the nipple to ignite against the edge, even when I press them on with a wood dowel rod. I've tried with the chambers unloaded to really seat them as far as I dare without setting them off, still the same problem.

I ended up getting Butler Creek/Uncle Mike's stainless steel nipples. Tried six dry fires and all of them worked. I don't expect any problems at the range. Learned a lot more about caps then what I knew before.