Did I make a mistake

Just finished an Stone Arrogant Bastard Clone.

This was my first full 5 gallon boil. Started with 6 gallons at boil

Split the 8 lbs of malt extract into 2 adds. One at initial boil, one with :15 remaining.

Ended up with 4.5 gallons, so I had to top off with .75 gallons of water.

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My OG was 1.067. Supposed to be 1.072 I assume this was due to the added water at the end.

However using Hopville Beer Calculus, my IBUS came in at 126.4. I tasted the water at cool down and it was very bitter.

I know Arrogant Bastard is a bitter beer, but 126 seems extraordinarily bitter.

There were 4 ounces of Chinook hops, added 2 oz at boil, 1 oz each with :15 and :05 left

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My questions are these.

1. Should I have put less hops in the beer doing a full boil.
2. Could late malt addition have effected it.
3. Should everything normalize over time. 2 wks in primary, 2 in secondary and 6 wks in bottle.

Thanks to all who respond

I find that unfermented wort is way more bitter than the final product. This will settle down after fermentation. I wouldn't worry

You will often see increased hop utilization in a full boil and with late extract additions, but it is simply too early to tell by sampling the beer now. The beer will come together over time. So, wait until the beer is done before making a final judgement. It may end up a little more bitter than planned, but then you can use this experience to calculate and compensate for this process in the future.

^^This^^. Brewing would be a very different hobby if you had to get everything right the first time!

You have lots of options, but it may take you several batches before you get the process dialed in the way you like it. You can scale back on hops; or stage the bittering hops at 60, 45, and 30 or something like that; you can try first-wort hopping; plus other options I'm not thinking of right now.

The good news is, you will get to drink the results of your experiments. Cheers!

The late additions will certainly affect the IBU calculation. It will probably not affect the actual bitterness as much.

You almost certainly do not have 126 IBU in your beer. Depending on who you believe, the limit of solubility of the bittering compounds in wort is around 100 IBU, and you diluted that by about 20%, so I'd guess that 80-85 IBU is the highest your beer can possibly be.

Also, like the others above, my experience has been that wort tastes much more bitter than the final product. It has a very sharp bitterness that fades. I've learned to ignore that when evaluating the taste of the wort. It hasn't shone through in the final product even once.

A lot of people have talked about an upper ceiling for perceived bitterness, usually near the 100 IBU mark. That is, you can continue adding bittering IBU's but your taste buds may not notice a difference. If that's the case, then anything over 100 is a number only and may not represent the product.

Agree on taste at yeast pitch not correlating at all with finished taste. Your beer will still have a little extra bite to it after fermentation until most of the yeast has dropped out. Carbonation will change things again. Have a homebrew and get another batch going.

I'm just curious, is there a reason why you didn't add the full amount of DME at the beginning of the boil?

More and more people are adding extract near the end of the boil ("late addition" if searching). It prevents the beer from getting too dark as the extract has already been "cooked" once when it was being created. You really just need to dilute/disolve and kill off any nasties that may be in the extract.

A late addition will also have some impact on the hop utilization.