I had the same issue with Bushnell scopes -- that big ocular bell, even with a fixed 4x. Used a small flat file to relieve the hammer extension, mounted it upside-down, and then used a Dremel cutoff wheel to remove the excess hammer spur. I am a lefty, so it did not interfere with the barrel release, but the right side (not the extension itself) did need to be trimmed and cleaned up a bit.
Currently using Weaver mediums, and might be able to get away with lows -- there's space to spare now. Learned the procedure from someone on this board, as usual!