I took him down to buzz today here in North Bend and had him scored (SCI), his bases were 15 4/8 and 15 5/8. Ended up with a 2/8 " difference from left to right horn, so overall pretty symmetrical. I don't know if most are like that or not, but I would guess they are.
My opinion is the ear tag rams that were original rams from Cleman do not have bases like on your ram. It's clear your ram and another one that is almost identical but one year older had the largest bases. Without any kills in that area to judge mass with on these rams, we assumed the bases were similar to Cleman rams so they were 14.5 and top out about 15" on the high end. I think all the ear tag rams don't go over 15" on the bases and most are 14-14.5. In judging them originally, I stayed conservative on the base mass not ever having seen a Chelan Butte ram killed and having a baseline on the mass. Once Brian/Ridgerunner killed his ram and we measured the bases out at about 15.25 or so, we knew we had 15.5" type mass on a couple of the other rams including your ram. The rams just grew bigger on the butte despite their Cleman genetics which was kind of surprising to me. Genetics means little but habitat is key. Brian's ram had good mass all the way through, great symetry, and good length.
It's a fun unit with great access, big rams, and it's relatively simple to hunt. I look forward to see what the unit produces in upcoming years and how they spread out. I'd like to see them fill in all that habitat between there and swakane.