I'm not talking about builds, here. I'm talking firearms that were purchased with the intent to leave as is yet ended up vastly changed.
There's a few guns I have that through the years I've just not been able to leave enough alone.
The first is my 10/22. It was originally a standard stainless wood stocked carbine. Over the years I sought to make it more accurate and comfortable. All that's left is the receiver, trigger housing, bolt, and a few small parts.
20130927_132119 by
Slick_Rick77, on Flickr
It shoots well to the point of boredom. It just effortlessly shoots tight groups. The wife and kid don't like it at all. They don't know what they're missing.
The next was this AR. It started as a ban era 20" A2 Hbar with non threaded barrel, neutered bayo lug, and big pin lower with sear block complete with the screw type pivot pin. It's gotta be the only Colt a guy couldn't recoup money on (I tried). Instead it evolved to it's current form, bastardized to the max. The factory barrel remains (albeit shortened, threaded, and re-profiled) as well as the original lower receiver and bolt group. I think Dissipators are the bees knees, and despite decades of resistance, I finally flat-topped it recently.
20180209_170420 by
Slick_Rick77, on Flickr
The optic on that thing was an item of many swaps until Leupold made a 1-4x with a #1 reticle and CDS elevation knob at my request. I call it the most expensive shotgun scope in existence. It's awesome. It's a bit of a sleeper with a FF sleeve under the handguards and a 3.5lb match trigger. The GG&G MAD 600yd elevation adjustable rear sight is an old school cool gem I recently acquired. It's still a little heavy at 10lbs unloaded, but I like it more than ever now.
Lastly is my poor Colt (now Caspian) pistol. It was purchased as a GI style until I learned the wonders of the beavertail and was disappointed by the accuracy, warranting a match barrel and bushing. Eventually parts from a few makers found their way on it, until the fateful day it fell out of a backpack from a moving vehicle. The frame was tweaked enough that a Caspian replaced it. The slide and a few small parts are all what remain factory. It still remains a great shooting and dependable pistol, and my favorite of all. I've spent enough time on it, and it is so ugly and with mismatched finishes that it's a keeper, regardless
20140723_111359 by
Slick_Rick77, on Flickr
20140723_111443 by
Slick_Rick77, on Flickr
My FIL had told me once that I've ruined my guns. Perhaps...but if they work better than they started and better suit my purposes I'll not care.