The key is a large punch.  I tried for a while with a 3/16" punch but couldnt get the power to transfer to the pins.  Then i saw a 3/8"x3" ss bolt on my bench and the pins moved with about 8 whacks from my ball peen hammer.

Just had a tshirt wrapped around the upper, and a chunk of 2x4 under the fsb.

I posted to this thread years ago with problems getting pins out and the above is what worked for me too.

I bought that exact base/holder for the FSB and some big ass hard punches at lowes.  That and a big hammer with solid backing...presto, pins moved a bit and then slid right out.  60 seconds after I whacked it, FSB was off.

Just went through this myself.  I'm no smith, but I've driven my fair share of pins out of FSBs, and I don't believe for a second that this thing was assembled with a hammer and a punch.  No question they use a press of some sort, probably have a neat jig and it takes them 11 seconds to apply 10 tons of force to them.  Went through all that so I could swap the triangle cap to a round and fit a Magpul MOE SL.  Lesson learned, won't be ordering any uppers with original parts from the 50s on them again.

Edit:  Make damn sure you put the pins back in the same hole, they deform the barrel and FSB as they're pressed in, and if you lose track of them, the FSB will be crooked.  Very excited to get to do this a second time.

Now that I have a giant flat punch, big hammer, and correct cradle for the barrel...it really is about a 2 minute job.

3 whacks with the hammer and the pin is out.  

I know this is an old thread but, tried for hours to get the taper pins to move, even tried to stare it down, no good.

Finally decided to use the vice.  Taped up the shaved FSB (except for the pins), placed a small nut over the large end of the taper pin (pin in the middle of the nut) so the vice would push the taper pin toward the small nut and the pin had a place to go. Had to hold the nut in place while initially tightening the vice.

Worked like a charm, in two minutes had both pins pushed flush, used small punch small hammer and with several hits both pins were out.