In my infinite wisdom, I decided that my nearly 5 year old PSA upper M4 profile 16" barrel on a Spikes lower with plain jane MOE furniture needed sprucing up. My goal was a semi-modernized M4 type variant like the US military was issuing in the mid-'00s to soldiers in the sandbox. So I bought a BCM 7" QRF so I could retain the FSB and got a B5 SOPMOD stock since I'm also a Mk18 fanboy. Well, had I known what a pain in the ass it'd be to do this rail install, I think I would have just started with a fresh upper.
The FSB pins were a huge PITA to remove. Don't bother with a flat tipped punch, you'll get nowhere, as I learned over about two hours of intermittent wailing on the things. Buy a 3/32" or larger nail set if you're going to buy the wrong tools. Then buy another set because you mushroom the first one. Just get a real tapered pin punch. Besides getting nail sets, the other best advice off Arfcom was "if you think you're hitting it hard, hit it harder."
Pro-tip: don't let your palm get pinched between the front barrel opening of the FSB and the grenade launching ring of an M4 profile barrel. You'll bleed if you do it right.
Picture taken after the bleeding stopped
I thought my troubles were behind me, but no, the AR gods did not shine down on me. No, they took a steamy shit right on my barrel index pin.
Probably because I took this picture threatening much pain to the barrel nut if it didn't yield.
Note: I did not actually use a vise-grip like a fucking savage, I have a proper Magpul armorer's wrench that worked a treat.
And yield the barrel nut eventually did. And holy shit, that thing was definitely torqued beyond the maximum recommended 80 ft/lbs. I applied heat from my heat gun, blasted it with Deep Creep, and wailed on my armorer's wrench with a rubber mallet until it finally started moving. I should have known something was off by how tough and gritty it was to still move.
Well, fuck.
And the inside of the upper is scratched up a bit now as well, which makes me question reusing it. Anyway, thought you all might enjoy my trip down fuck-up lane.
I guess I now have an "excuse" to buy a nicer upper and barrel now...