An archer should be at or near 400 dex
392 is the cap for casting (archery) speed, but the higher dex still does minimally more damage b/c that is like Intelligence for a caster
Your cap would be:
Your races starting stat, so say for a briton (60)
Your starting points you put into it (up to 18, maybe 15 is typical)
Your suit and items/template (up to 101)
Buffs (should be 155, but if you self buff instead of bot, perhaps a bit less)
Your rising stats (49 at level 50)--verify this, I am assuming dex is an archer primary rising stat, but I have never played one
Your Realm Abilities (Aug Dex)
A lurikeen, which starts at 80 dex should easily hit the 392.
The number you gave does not seem possible if you are including the number fully buffed. I am assuming that was your unbuffed number.
Edit--The number you are saying, 22 over cap only applies to your template. The max is 101. If yours says something like 95/95 (22 over cap), this means you need something with 6 more dex cap to reach the 101 cap. Anything after that is not used, but you should be 101/101, and it is common to have some over cap b/c so many of the items you will use will have dex in them.
Edit #2--getting 392 does not give you a 10% reduction in bow casting speed. You should also have 10/10 archery speed. At 10 archery speed bonus, 392 hits your maximum bow casting speed. This value is widely accepted from multiple player tested logs. You absolutely should never have less than 10 archery speed (with your bow equipped) b/c so many of the items have it on it. So to summarize, with buffs, you should be at 392 and that should be your goal. 400 or 405 is okay b/c the extra will help damage a small amount but values over 400 have been said to have a very limited return. You also should have 10 archery damage and 10 archery speed in your template with bow equipped.
Edited, Nov 18th 2012 4:07pm by thuri
Edited, Nov 18th 2012 4:10pm by thuri