Hi, I usually do the beer/water also with pickling spices and cook it all day on a low simmer and it's always tender.
Maybe you just need a little more time cooking it? Good luck.
Kim

The main clue is don't bring it to a roaring boil...keep the temp at the barest simmer....and cook it until it's fork tender. Allow atleast 4 hours for a 3 1/2 pound piece of meat....and the same for a 4 1/2 pound piece.
Loooong sloooooow cooking.
Linda C

Got it thanks !!!!

I have one in the crock pot now, with lots of water. I put it in the night before and let it cook on low until supper time today. It ends up very tender.

I had to cook 80 lbs of corned beef yesterday...I let mine come to a boil-then simmer for 4-5 hours-depending on the size of the meat. I always put a whole onion in with the meat as well. Oh-and as that 'scum' develops on top of the water? Keep skimming that off, during the cooking period.
Last night-Elton Brown on the Food Network said by adding a Tbs of salt petre (I always spelled that peter!) to the water-it will keep the corned beef nice & pink in color-hmm-I didn't and my meat's nice & pink.

Yet another reason whi I don't like Alton Brown...he puts his face close to the camera and tells you all these secrets! When in fact most are 1/2 truths.
Yes, saltpeter ( the most common way to spell it, but in UK it's most often spelled "re") does keep the meat from turning color...but processed cornbeef that you buy already has the nitrates in it.
If you corned your own meat and didn't add sodium or potassium nitrate, it would be sort of greyish.
Linda C