From speaking with customers, it seems BCM FSB taper pins are harder to remove than some others. When we do it here, we can knock the pins free in under 60 seconds.
Here are some basic pointers on the way we remove them.
1) It takes Two. You will need a buddy to hold the upper group stable as you pound out the pins. You will not be able to get a good concentrated force on the pins if the upper is wobbling around (even a little bit).
2) Action Jackson. You will need a couple of action blocks (see Brownells for a good selection). These will be great platforms to stabilize the barrel. Also get the Brownells FSB block. You may have to mod the shape of the FSB block if using a free float.
3) Installed from starboard side. Milspec FSB are drill and the reamed for taper pins. The reamer runs from the right to the left (pointing the muzzle at the bad guy). So BCM pins need to be removed from left to right. Cannot be done the opposite way.
4) Secure that carbine. Using action blocks and the buddy system secure the upper group so the left side is facing up.
5) Get a fat one. We do not use those small radius head punches to break the pins free. We use a much fatter punch (5/16”). It’s a meaty sucker. Lots to hang on to, and enables you to put some force on the hammer. Using a 5/16” punch and a 12oz hammer, give her a smack. Anywhere between 1 and 6 smacks, and the pin moves. All you want to do is to get it to move to about flush.
6) Grab a skinny one. Now get the tiny little 1/8” punch to push the pins out of the FSB. They are already broken free, this just drives the fully out. Tap, tap, tap.
7) Celebrate. You are done. Do the banana dance.
Hope this info helps...