the barrel is now contoured, but there is still much to do
remember that little disk from earlier, well allow me to explain, on a regular bren barrel, the barrel and area with the locking lugs is all one piece, it is not threaded on, because of this, on a factory barrel no shoulder is needed for the locking lugs area (what I will call the barrel extension) to index on and thread up against. So on mine (given that I used a barrel extension that I made from an old bren barrel and this would neeed to be threaded on) I had to make a shoulder, but as the barrel sleeve/trunion butts right up against the extension and the barrel tenon diamter is larger than the diameter under the trunion, no shoulder would normally be available, so I cutt the barrel sleeve/trunion back .060 and left a shoulder built into the barrel itself.
picture of the cut barrel sleeve
the factory barrel is quite thin and so of course, so is the internal diameter of the gas block, so I opened it up. the portion of my barrel infront of the gas block is .700 and the diameter of the barrel under the gas block is .715. at this point the walls of the gas block will become very thin, I'm going to try a .725 profile barrel on my next one, but that may be iffy.
now that the barrel is contoured and the barrel sleeve and gas block are both ready to go on, let's first take care of the dangerous end of the barrel, I cut a 5/8 X 24 tenon for a muzzle break a friend gave me awhile back, I think it's made my ptg. All I know for sure is that it has about the shortest tenon I have ever seen on a 5/8 X 24 brake, with a max tenon length of only like .370. So I cut the tenon at .360 and hope it indexes close once threaded, luckily it did and I only needed to remove .002 extra to get it on in the correct orientation.
alright, after finishing that and crowning the barrel, it was time to assemble. putting on the gas block and barrel sleeve requires a 20 ton press and a good eye. I think it came out well and the alignment is just about perfect, (there is about a degree or two flexibility on line up for it to still function fine, this one was bleep close to right on the money)
and we are assembled and ready to go, getting gas port sizes worked up for the load I will be shooting will take a little while as I do load development and settle on what I want, but other than that it is good to go.
So of course I through it in my gun and test fired just to double check my work, and good news, nothing blew up this time
and that is all that I have for you guys today, hope you have enjoyed so far, as more projects develop or modifications are made I will continue to post them in this thread. Still a few more barrel and configurations I want to try with this gun and it has been quite a bit of fun. If I can remember I will also post my single stage trigger modification which takes the factory bren trigger down to around 2-2.5 lbs without changing any spring weights.
