I'm not sure on the pressure either, maybe someone else would have a clue, You might (I've thought about it not 100% sure it would work) take your 170 .355 horns and use them in your 35, they do work ok in my 358 and shoot pretty dang good, but there is no velocity gain from my 180's so it was a not productive experiment . when i try using the 35 die there isn't enough neck tension to hold them so if I was going to do that I would get a separate die and put a 9 mm resizer in it. and then you could use the same bullet in both.