The 505A is very similar with the difference being box finish and the pearl additive.
I would imagine with very slight box adjustment you cand get a very similar reaction to the 505C by using the 505A.
That being said EBI goes through bowling balls very quickly these days. Many have been discontinued after being released in August. There will be another 5C series it will likely have a slightly different core. Like a 506 or 507C,A,and T series.
The 4s are likely all going to be overseas releases.
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