So a couple months ago I got this silly idea that it would be fun to build an BCL102 from scratch to use as my main hunting rifle (pre-Stag 10 release of course), so I did a pile of research, ordered a receiver set and a bunch of parts, most of which showed up right away, but for a few important parts like the barrel and handguard I ordered from the states and of course had to wait for them to be imported. As it would be the import was delayed and took an extra few weeks in addition to the month wait, and so I waited. Well they finally got here a couple days ago, so I figured I'd make it my weekend project. Which I of course started at 8pm on a Friday night, but of course then I was hooked and couldn't stop and it ended up taking me until about 2:30 am to finish. 
I've never done an AR build before so it was going to be a learning experience. I youtubed it up, opened a "how to" on my second monitor, pulled my mostly stock BCL out to use as a reference, converted my low dresser into a work station (don't judge, it's the renter's life for me, got no workshop). I took my time following the instructions the lovely people of the internet provided and aside from a couple minor hiccup and taking what is I'm sure far longer than it should have, everything went fairly smooth. Had to work the cerekote down on the buffer retainer hole to get it to spring nicely, and I had to open up the rear takedown detent hole with a drill as it was way too small, but other than that my receiver set seems to be in spec (for a BCL anyways) and seems well made and everything else fit nicely.
Starting to assemble the lower, using plenty of tape on the receiver to reduce the chance of scratches.
Here is where I ran into my first conundrum, turns out the Geissele lower parts kit I got doesn't come with the trigger pins, since it's the "less trigger" version, but the TriggerTech trigger also didn't come with trigger pins either since it expects you to re-use your old pins. Not to be stalled so easily, I stole them off my 1st gen 102 so I could carry on with the build, I'll have some of those on order shortly to put it's trigger back in, I may use this as an excuse to upgrade that one's trigger as well.
Everything else went relatively smoothly, until the lower was almost completed and I was attempting to install the buffer retainer, and it shot across the room. The spring? Landed nicely in the middle of my open gun case on my bed. The retainer? In an incredible display of Murphy's law, bounced off the wall and down behind the about 8 inch gap between my bed and the wall, and down the furnace vent, coming to a stop around the corner about 3 feet down it just out of reach.
Yes, it's the tiny Black thing way down there just past all the scuff marks, (again, don't judge me on the disgusting vents, it's a rental haha) I could see it with my phone camera but I couldn't reach it. I could just barely and somewhat painfully get my arm around the corner but still couldn't get it. After about 20 minutes of trying I was able to use the additional reach of an empty paper towel roll and scootch it close enough to grab it. After which, I successfully installed it and finished the lower!
The upper was actually much easier than I expected it to be, having never done it of before of course. I was mostly a little intimidated by the barrel install. The SLR handguard conveniently comes with a wrench for it's barrel nut and it has a 1/2 adapter for a torque wrench. I taped up the upper with masking tape, even more than the excessive amount I used on the lower, and pinched it in the vice sideways (bought a 5" vice last week at CanTire for $50, yay 1/2 off sales!) between a scrap of 2x4 which was across the pic rail, and a scrap of 2x6 which stood up fits nicely in between the takedown pin hole studs, tightened this setup snug in the vice, and torqued the barrel on, following the rule of 3 to condition the threads (on-off-on-off-on), kinda time consuming but it seemed to work well.
It got a bit of scratched where the barrel nut was hiding it and wouldn't let me tape it, the Fulton Armory barrel came with this nice stretchy net thing which works great to protect it while working on it so the rest was pretty safe. Everywhere I read said the roll pin for the gas tube can be a pain, and people try to hold in place with pliers or use make shift tools and such to make it easier. After trying with a pair of pliers and deciding I really needed a third arm, I stopped and thought about it for a minute, after which I poked a round hole in a piece of masking tape, taped it in place over the hole so the pin stood up on its own, and gave a couple taps with a hammer and it was started nicely. Put the gas block on screwed it in place, the business card that came with the SLR gas block was about the perfect size to create the gap so the gas port and gas block holes lined up. Put on the handguard, then I put the muzzle brake on, but I need a wider shim than was included to time it properly. That's all I need pick up now to "finish" the build. I put the do-dads like the Magpul rail covers and the vertical fore grip, swapped the scope off my other (currently floppy triggered BCL), and she should go "bang" now!
I'm very happy with how it turned out, just about exactly as I wanted it to.
Hope you enjoyed my little AR-building adventure! I'll post the parts list as a comment.

I've never done an AR build before so it was going to be a learning experience. I youtubed it up, opened a "how to" on my second monitor, pulled my mostly stock BCL out to use as a reference, converted my low dresser into a work station (don't judge, it's the renter's life for me, got no workshop). I took my time following the instructions the lovely people of the internet provided and aside from a couple minor hiccup and taking what is I'm sure far longer than it should have, everything went fairly smooth. Had to work the cerekote down on the buffer retainer hole to get it to spring nicely, and I had to open up the rear takedown detent hole with a drill as it was way too small, but other than that my receiver set seems to be in spec (for a BCL anyways) and seems well made and everything else fit nicely.
Starting to assemble the lower, using plenty of tape on the receiver to reduce the chance of scratches.
Here is where I ran into my first conundrum, turns out the Geissele lower parts kit I got doesn't come with the trigger pins, since it's the "less trigger" version, but the TriggerTech trigger also didn't come with trigger pins either since it expects you to re-use your old pins. Not to be stalled so easily, I stole them off my 1st gen 102 so I could carry on with the build, I'll have some of those on order shortly to put it's trigger back in, I may use this as an excuse to upgrade that one's trigger as well.
Everything else went relatively smoothly, until the lower was almost completed and I was attempting to install the buffer retainer, and it shot across the room. The spring? Landed nicely in the middle of my open gun case on my bed. The retainer? In an incredible display of Murphy's law, bounced off the wall and down behind the about 8 inch gap between my bed and the wall, and down the furnace vent, coming to a stop around the corner about 3 feet down it just out of reach.

Yes, it's the tiny Black thing way down there just past all the scuff marks, (again, don't judge me on the disgusting vents, it's a rental haha) I could see it with my phone camera but I couldn't reach it. I could just barely and somewhat painfully get my arm around the corner but still couldn't get it. After about 20 minutes of trying I was able to use the additional reach of an empty paper towel roll and scootch it close enough to grab it. After which, I successfully installed it and finished the lower!
The upper was actually much easier than I expected it to be, having never done it of before of course. I was mostly a little intimidated by the barrel install. The SLR handguard conveniently comes with a wrench for it's barrel nut and it has a 1/2 adapter for a torque wrench. I taped up the upper with masking tape, even more than the excessive amount I used on the lower, and pinched it in the vice sideways (bought a 5" vice last week at CanTire for $50, yay 1/2 off sales!) between a scrap of 2x4 which was across the pic rail, and a scrap of 2x6 which stood up fits nicely in between the takedown pin hole studs, tightened this setup snug in the vice, and torqued the barrel on, following the rule of 3 to condition the threads (on-off-on-off-on), kinda time consuming but it seemed to work well.
It got a bit of scratched where the barrel nut was hiding it and wouldn't let me tape it, the Fulton Armory barrel came with this nice stretchy net thing which works great to protect it while working on it so the rest was pretty safe. Everywhere I read said the roll pin for the gas tube can be a pain, and people try to hold in place with pliers or use make shift tools and such to make it easier. After trying with a pair of pliers and deciding I really needed a third arm, I stopped and thought about it for a minute, after which I poked a round hole in a piece of masking tape, taped it in place over the hole so the pin stood up on its own, and gave a couple taps with a hammer and it was started nicely. Put the gas block on screwed it in place, the business card that came with the SLR gas block was about the perfect size to create the gap so the gas port and gas block holes lined up. Put on the handguard, then I put the muzzle brake on, but I need a wider shim than was included to time it properly. That's all I need pick up now to "finish" the build. I put the do-dads like the Magpul rail covers and the vertical fore grip, swapped the scope off my other (currently floppy triggered BCL), and she should go "bang" now!
I'm very happy with how it turned out, just about exactly as I wanted it to.
Hope you enjoyed my little AR-building adventure! I'll post the parts list as a comment.




















































