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My sons new 300 AAC Blackout

4K views 37 replies 12 participants last post by  Coils 
#1 ·
My son has finally graduated from his Rossi.357 single shot rifle to something a little bigger for hunting. I was out shooting some hand loads through my ultralight ar and he wanted to try it. I was a little hesitant but let him try. His first group (eotec exps and magnifier) was at 77yards all in 3/4 of an inch center to center. His second group was 1 3/4 of an inch. I had been reading up on the 300 AAC Blackout. Basically a .221 necked up for .30 cal and when loaded to supersonic velocities it is a match for 30-30 and 7.62x39. Soooo i ordered a green mountain .308 gatlin barrel for 40 bucks, chopped the chamber, reprofiled and built him one. At first he wanted a m4 handguard but then wanted me to make him a free float tube. Knurled. With ball nose grooves. Not vented. Oh and make the grooves SPIRAL. I spent a few hours in the shop and here she is. I still need to bead blast and camo it, plus that is a Neighbors lower that was handy for the pic (WARNING that is a moores machine shop lpwer DO NOT buy one)
 
#3 ·
Dangit, tease!!!!! LOL. Sounds interesting. I look forward to seeing it.
 
#7 ·
I hated it at first. He wanted the grooves twisting the other way but hes a righty so i cut them this way for a good grip. After some rattle can black it looks better and i guess seeing him staring lovingly at it the last few days its growing on me. One day i wont be able to make him this happy so he can have it his way. Except he is talking of painting ot blue...i cant do that.
 
#9 ·
I like the 300 BLK round. BigAl and I just got done building a couple of these for ourselves. I found some reconditioned LC brass in 300 BLK for 16.50 per 100. I still need my AAC flash hider and a can for it, but the rifle is done .

PM me if you need the contact info for the brass.
 
#14 ·
:notworthy And here I thought you did it with your dividing head and the green machine. Building your own cnc is even better! I do have a couple builds that I'm slowly working on that I haven't got handguards yet.
 
#15 ·
Lol the dividing head had a cogged belt gear machined for it, a stepper motor, bracket and belt added and it became the fourth axis on that is green machine that i put 3 axis on. Its hard to believe but i go to the "real" machine shop in town now and cuss about counting turns of the dials and where to account for backlash etc.

I can cut zigzags on the tube,spirals multipitch spirals etc.
 
#17 ·
First test fire was today! The gas port isnt drilled but that and little rounding of the chamber mouth is all that is left on th upper. Fired case was perfect but the sharp chamber mouth scratches or hangs up manual feeding from the mag. No biggie as i didnt want to do it before assembly and testing. My wife and i were surprised at th sound level of the round and the ABSOLUTE lack of flash and powder burn on the test board it was strapped to. Pretty quite to for an ak powered round.
 
#18 · (Edited)
VZ, I'm not well versed on the AR's, so I apologize for my ignorance, but how do those handguards on your 450 and your son's 300 blackout attach to the upper? They look great.
 
#20 ·
Oh, ok. I get it now. Thanks BigAl.
 
#21 ·
Big Al is right. That is how some attach. But since I cut these to match, there is the .125" wall tube that is thinned further on the lathe. Then I spin an internally threaded nut with a smoot od that will allow tube press fit over the nut. Once pressed on and ensured it is true to the barrel I drill a hole from the tube into the nut and heliarc th hole shut. This locks the two together permanently and very solidly. I then turn or file or sand the top of the weld to make it disappear. Then I torque the tube barrel and receiver to spec, mark the location of the gas tube, remove, drill one hole for the gas tube then reinstall. Done.
 
#22 ·
Cool. It looks great.
 
#25 ·
That looks very nice VZ58. That handguard really sets it apart from a kit gun. What kind of muzzle break are you going with? What load are you going to use for deer? How does the GMB mini gun barrel shoot? Too many questions?
 
#26 ·
We both got some trigger time today. Had to get the.gas port up to .125" for reliable bho. 20 rounds fired of hornady 125 grain. One miss feed bolt over round. Apparently this round does NOT like the gm barrel.my best group was 1.875" @100 yards. My average was 2.5" My son was consistant at 2.5" groups.. now i know you may be saying thats not bad. But i was expecting 1-1.5" groups. Yes it is plenty good for hunting where i am taking him. Its 77 yards and under. Heck i have a colt 5.56 that cant shoot under 3" and a H&K 5.56 that is lucky to do 1.5". But after all the hype i was expecting better. I may recrown the barrel and who knows sometimes a new barrel takes a few boxes to settle in.
 
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