Taper pins can be removed without much difficulty. They need to be driven out from the opposite direction they went in (put your punch on the smaller end, to drive them out). Generally, they're installed from right-to-left, and removed from left-to-right. It takes some proper hits with a hammer and punch (nail set or concave face punch works best), to get them moving. But once they're moving, any punch will do.
However.... barrels that have had taper pins installed will have holes through the underside of the barrel, where the gas block was. So, replacement gas blocks need to cover that area. Otherwise, it leaves a nasty looking blemish on your rifle, or needs to be pinned and welded to fill the hole.
If you have some basic hand tools and a vise, there's always the option of chopping the sight tower.
I did one last week on a PSA upper. A lot of people try to remove as much material as possible, to give it a streamlined, lightweight look; but I went for anti-snag and functional. As a bit of a bonus... the sight tower was warped, anyway. So it was a waste of metal, to begin with.
I clamped the barrel in my vise, left the sight base fully installed, and hacksawed the tower off with a "mini" hacksaw (it came in a little tool kit that my little brother got for his 8th birthday, umpteen years ago
). I cut from the inside, out, on each side, so starting the cut would be easier.
Then, I covered the barrel and as much of the grip cap as possible with painters' tape, profiled the front end with a couple mill files, did what I could to the rear end without damaging the grip cap.
Then I removed the sight base and grip cap, and reinstalled the sight base (taper pins just snug enough to hold it). I could have just clamped it in my vise, but I wanted to use the flat on top of the picatinny rail as a point of reference while I eyeballed the profile for the gas block (it also gave me more room to work with the files).
With it reinstalled, I profiled the rear portion of the block, shaped the transition I wanted from front to back, added some fillets to all edges and corners (which isn't apparent in the pictures - the lighting only picked up flat surfaces), and hit it with some 120 grit sandpaper to remove the file marks. (80 grit probably would have been good enough, but 120 was already on the bench
).
Once done, I removed the block, removed the gas tube, thoroughly cleaned the new "low profile" gas block, and cold-blued it. With reassembly, I was done.
The whole job took about 2.5 hours. ....Maybe less, since I took a few breaks.
(Note: The taper pins were not fully installed for the above picture. I didn't want to wake up the family at 2 am.)
