bradders Posted April 27, 2017 Report Share Posted April 27, 2017 I know you all like looking at how stuff's done, so here's another pictorial Todays project: Machining a Mega Machine upper receiver I have a few of these uppers, and the problem with them is that they're too thick at 10mm wall thickness, which prevents me fitting one of my World Famous® Charging Handles. To make the very best of this, the ideal solution is to remove material from the sidewalls of the receiver, 4mm to be precise, which brings the wall thickness down to .250" That should be Billety enough for anyone! Machined vs unmachined sides Doing this however leaves the upper too slab-sides, so reprofiling of the upper and lower facets is required After this the charging handle slot needs machining to suit the handle. The Mega uppers are already partially machined for sidecharginbg, but it is far from suitable. The slot requires lowering, lengthening and widening Chamfered. This will be finished by hand later After all machining is done, it's off to the bench for finishing. The first step is to remove the machining marks Reprofile the rear edges to blend and match Finally after all radiusing and deburring and a clean The finished item Tomorrow we blast and Cerakote® ETA: Cerakoted them yesterday, so here's the finished item And here's some pics of a barrel I fluted and crowned yesterday Link to comment Share on other sites More sharing options...
snakeman Posted April 27, 2017 Report Share Posted April 27, 2017 Very impressive, brads...out of interest, how long did that receiver take to complete? Cheers Link to comment Share on other sites More sharing options...
bradders Posted April 27, 2017 Author Report Share Posted April 27, 2017 Very impressive, brads...out of interest, how long did that receiver take to complete? Cheers All in, probably about 90 minutes each, but I was doing 6...and with all the other things like drilling and tapping bolt carriers, as well as other jobs, today turned into another 12hr day Don't know where the times goes some days Link to comment Share on other sites More sharing options...
snakeman Posted April 27, 2017 Report Share Posted April 27, 2017 Cheers bradders...let's hope they go to a good home ATB Link to comment Share on other sites More sharing options...
bradders Posted April 30, 2017 Author Report Share Posted April 30, 2017 Finished pics added to OP Link to comment Share on other sites More sharing options...
lapua Posted April 30, 2017 Report Share Posted April 30, 2017 Very nice Link to comment Share on other sites More sharing options...
johnnyb0_1 Posted May 2, 2017 Report Share Posted May 2, 2017 Very interesting. Thanks for posting. JP. Link to comment Share on other sites More sharing options...
chaz Posted May 2, 2017 Report Share Posted May 2, 2017 Lovely finished item. British engineering at it's best! Link to comment Share on other sites More sharing options...
silent_varmintor Posted May 19, 2017 Report Share Posted May 19, 2017 what is the barrel spec, length, calibre ? Looks lovely and short. Would be a beautiful 300 blackout truck AR Craig Link to comment Share on other sites More sharing options...
bradders Posted May 19, 2017 Author Report Share Posted May 19, 2017 what is the barrel spec, length, calibre ? Looks lovely and short. Would be a beautiful 300 blackout truck AR Craig It's a .22lr, 12" made from a Sassen blank That said, I've done plenty of .300Blks/Whispers and .223s in 12" configs I did the first one in 2005 when the only option was .300 Whisper Link to comment Share on other sites More sharing options...
silent_varmintor Posted May 19, 2017 Report Share Posted May 19, 2017 Interesting What would be average speed, and muzzle energy with both 223 and 300 Blackout with a 12" system ? I would love something like this for a dedicated thermal system for fox both walk around and from truck. Link to comment Share on other sites More sharing options...
bradders Posted May 19, 2017 Author Report Share Posted May 19, 2017 These are Swedish military findings regarding barrel length and 5.56mm 62gn SS109 ammo It should be relevant for all 62gn/SS109 ammo types Barrel length SS109/M855 V4 bullet velocity 210 mm (8.3 in) 723 m/s (2,372 ft/s) 240 mm (9.4 in) 764 m/s (2,507 ft/s) 270 mm (10.6 in) 796 m/s (2,612 ft/s) 300 mm (11.8 in) 825 m/s (2,707 ft/s) 330 mm (13.0 in) 843 m/s (2,766 ft/s) 360 mm (14.2 in) 866 m/s (2,841 ft/s) 390 mm (15.4 in) 878 m/s (2,881 ft/s) 420 mm (16.5 in) 892 m/s (2,927 ft/s) 450 mm (17.7 in) 906 m/s (2,972 ft/s) 480 mm (18.9 in) 915 m/s (3,002 ft/s) 508 mm (20.0 in) 922 m/s (3,025 ft/s) As for Blk, well subsonics will be below 1150fps, but with a 125gn .30 for example, you'll be getting about 2100-2150fps with a 12" barrel Link to comment Share on other sites More sharing options...
MrCetrizine Posted May 19, 2017 Report Share Posted May 19, 2017 Before I sold my Blackout I was running 200gn bullets at 1080fps from a 12" 1:7 with what I'd describe as .22lr accuracy but with a touch more range. As Bradders says, supersonics in the 125-135gn range ran around 2100fps but I found them more accurate at 1800fps. Link to comment Share on other sites More sharing options...
gazzarM1 Posted May 20, 2017 Report Share Posted May 20, 2017 is a naked upper receiver classed as a licensed item ? Link to comment Share on other sites More sharing options...
bradders Posted May 20, 2017 Author Report Share Posted May 20, 2017 is a naked upper receiver classed as a licensed item ? It is now according to the recent changes Link to comment Share on other sites More sharing options...
silent_varmintor Posted May 23, 2017 Report Share Posted May 23, 2017 Thanks for that info regarding bullet speed, Something for me to think about. Link to comment Share on other sites More sharing options...
alpha1 Posted May 23, 2017 Report Share Posted May 23, 2017 The tool you are using to cut the flutes what is it Link to comment Share on other sites More sharing options...
bradders Posted May 24, 2017 Author Report Share Posted May 24, 2017 It's called a Convex Radius Cutter Link to comment Share on other sites More sharing options...
alpha1 Posted May 24, 2017 Report Share Posted May 24, 2017 Thanks. Interesting stuff thanks for posting. Link to comment Share on other sites More sharing options...
alpha1 Posted May 24, 2017 Report Share Posted May 24, 2017 Do you mind if I ask were I can get one of those convex radius cutters from. Link to comment Share on other sites More sharing options...
bradders Posted May 24, 2017 Author Report Share Posted May 24, 2017 I got mine from a supplier in Sheffield, (can't remember who it was) but they are available elsewhere Google is your friend Link to comment Share on other sites More sharing options...
alpha1 Posted May 24, 2017 Report Share Posted May 24, 2017 The only ones I can find are in the USA. I will keep looking. Thanks. Link to comment Share on other sites More sharing options...
bradders Posted May 24, 2017 Author Report Share Posted May 24, 2017 http://www.mscdirect.co.uk/CGI/INSRCH?ns=1&oldNtt=&oldNtk=&oldURLVar=&scrNtt=convex+radius+cutter&image.x=0&image.y=0&Ntk=Keyword+Search Link to comment Share on other sites More sharing options...
alpha1 Posted May 24, 2017 Report Share Posted May 24, 2017 Fantastic thank you. Link to comment Share on other sites More sharing options...
bradders Posted May 24, 2017 Author Report Share Posted May 24, 2017 Fantastic thank you. So are you going to start fluting now? Link to comment Share on other sites More sharing options...
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