You can always swing by
http://bitmunitions.com and see if we carry some good ammo at prices you are willing to pay! (Hint: We sell all products 15-20% BELOW USD market value. Great way to get extra value from those bitcoins you have.)
Also I agree the
https://en.bitcoin.it/wiki/Trade might be the best resource for customers looking for merchants.
Placed an order @ Bitmunitions.com for some Winchester M22 .22 Long Rifle 40-Grain 1000-Rounds.
I couldn't resist the prices I saw

and not a bad selection either.
I really like the concept of purchasing ammo with bitcoins.
I hope this is a successful transaction, as I would like to purchase more ammo this way in the future.
Will update.
Cheers.