More faking it while making it

Because this is a low dollar range toy, I didn't want to buy a high end match barrel that cost more than all the other parts of this project combined(and I'm not a good enough shot for a barrel like that anyway).  The barrel I'm using is an 18" CETME barrel from Apex.  It is a very nice barrel, well machined and reasonably priced.  There is one problem with it though, it's 18" and not the 25.6" of the PSG-1, and it's too thin compared to the heavy barrel contour of the PSG-1.  Because of that, it looks obviously too short and too thin with my 3D printed PSG-1 style handguard.

Don't worry though, I have a plan for that.  The muzzle on the Apex barrel is threaded 5/8-24, a standard size for 30 caliber muzzle brakes and flash hiders.  So I decided that I would just make a barrel extension that threaded on.  In addition to being an extension, it's also a sleeve that slips over the barrel until it's under the handguard to make it appear that the whole barrel is heavier.  I used some 3/4" 1144 stressproof steel bar(because that's what I had handy), drilled all the way through it with a really long 11/32" drill bit(three actually, short, medium, and long, and it took me all afternoon to drill on the lathe), then counterbored it to fit over the barrel, with a smaller step 5" down for the threads, and tapped it with an $11 e-bay 5/8-24 tap.  I had my doubts about the e-bay tap because it was so cheap, but it cut great and still looks like new.  I had to get creative with the tap holder because the tap is 4" long and the threads are 5" down in the hole, and I ended up sacrificing a thin wall 12 point socket for it.  Here's where the extension sits on the barrel, if you could see a cutaway of the extension, you'd see about an inch of threads in line the barrel's muzzle.

With the extension in place, the overall barrel is the same length as the PSG-1, and looks much better with the handguard.

I also put a recessed crown on the barrel extension instead of the flat crown on the PSG-1, mostly because I don't trust myself not to ding it up.  11/32 is only .035" bigger than .308, so it's not too noticeably bigger at a casual glance, and hopefully it won't affect accuracy.  I also don't know for certain that the drill didn't wander, but being cut on the lathe all from one direction hopefully it will be close enough.