Back in 2012, I won an AR-15 lower and matching flat top upper from Dreadnaught Industries as a prize package for Kilted to Kick Cancer.
Since I already had one AR-15, I wasn't in any big hurry to build this one out, and the budget being what it was for many years, parts were hard to afford and came piecemeal: One year, I managed to scrape together some coin and I bought a .300 BLK barrel for it at the NRAAM in Nashville. A year later, I bought a lower parts kit after stashing away a couple bucks from each paycheck. This past year, I picked up a bolt carrier group with firing pin and a telescoping stock, buffer tube and spring, and a few other parts for the upper.
I'm finally down to the last few items: Gas tube and block, compensator, and a free float handguard are all that remain.
So this past weekend, Friday being payday and all, I went to my LGS and picked up a gas tube and block. I was reasonably sure it was a 9 inch tube that I needed.
I was wrong.
So back to the LGS I go, and I picked up a 7 inch gas tube. Spent an hour trying to get the rolling pin into the block and tube, finally gave up. I'll probably take the upper to the gunsmith and ask him to install it for me, along with the dust cover. In the interest of safety, I'll probably have him give the entire thing a once-over to ensure it's built correctly before I fire it.
And yes, I have different magazines for the .300BLK rounds and my 5.56 NATO rounds. My 5.56 AR-15 is all black (because of course, right?) while I purposely built my .300BLK in Flat Dark Earth accessories (stock, grip, and will get a FDE fore end), so I figure FDE magazines would be a good way to determine which mag has which round.
At any rate, I think I can have this done by the end of the year, thus bringing to a close a 5 year long AR-15 build project.