AR build in -39mm continues to impress

Lefty38-55

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Joined
Feb 17, 2016
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159
Location
New England
Gents:

OK, a precision rifle, never mind a precision AR ... she is not. However, I built this as I have a ton of bulk -39mm on hand and I have successfully used my SKS on deer whilst using 124-grn softpoints (good hunting ammo by PMC). In the SKS that I tricked out, she's a solid 1.5" arm all day at 100-yds for 3-shot hunting groups. I thought that maybe a good AR build could be better, but wow … am I simply amazed!

Intro – I admit right up that I was never really into the ARs, but always did my shooting offhand, and one day the high power boys got me to give up my trusty M1 and try a 'black rifle'. Oh boy, I was hooked, but I think more so do to the inherent GENIUS of the platform … and not the caliber. I bought a precision 24" heavy barrel AR and then built a 20" heavy fluted Wylde-chambered 1-in-8" upper for offhand use with sights (off the same target/precision lower - not pictured), but a fan of the 5.56mm cartridge ... nope, I am not. So I'd pick my M1 back up, haha!

Build – But one day I was looking at my -39mm stores and thought 'Geeze, maybe I should build an upper in that caliber". Now admittedly magazines are the sore point, but I got some good 10-rounds and quite a few pre-ban high capacity ones. And before anyone asks … this is the only picture I have of this build, so of course I took it with a big mag in there, but for hunting I only use ones blocked to whatever the State restriction is. The picture shows all I have into it and to a point I think many of the components helped wring out the accuracy potential of this rifle and caliber/cartridge.

Man, is she accurate! I firmly owe it all to the straight in-line design of the Stoner platform and this rifle takes the capability of the 'lowly AK cartridge' to another level. Knowing many arms are over-gassed, I went with a JP Ent adjustable gas port. When I went to function test her and tune the adj post, my last mag was a mag dump of a 30-rounder, but only filled to 27 or 28 or so. My buddy said "Look at your brass pile", as all the empties (steel cased no less) landed into about a 2' square area in the sand pit we were shooting in, landing out & behind at about 4 o'c from the muzzle.

More impressive is how she shoots, as I've tried many brands of bulk ammo and for plinking, none are worse than 2 MOA or less. Simply amazeballs amazing! That same PMC hunting ammo will put 3-shots groups under an inch at 100Y, lie 3/4" groups, and using Brown Bear bulk, I once shot a 5-shot < 2" group at 200Y, from the benchrest setup on the high power range, off bipods. Witnessed to boot.

Man, I just LOVE the AR in this caliber! I call it my '308 Short', as she has much more 'thump' than the 5.56. Everyone who shoots it wants to shoot it more than they do this rig when dressed in its 5.56 form, or other ARs present on the range. I recall hearing that saying "If you can't hit it with an AK … you can't kill it with an AR" … well I sure wouldn't want to be out in front of this one …

AR-39mm_zpsjmxrjptl.jpg
 
I use C products 6.5 Grendel mags of lower capacity in mine with no issues.
Mine also ejects into a nice "pile" but at 7 o clock! Easily grouping 3/4 in with a Hornady bullet over RL-7. It recently put three hogs to bed, each with a single shot into the boiler room. All at or slightly more than 100 yards.
 
The choice was made for me! The barrel is a Green Mountain Barrels product and comes with a carbine length port.
I have had great results with two of their A1 12 twist barrels and thought I would try their -39 offering.
The first load I tried cycled correctly and accurately, been happy since.
BTW both A1 12 twist barrels shot very well up to 60 grain pill (6o V Max / 26 Varget shoots great). Anything heaverier is out of the question.
 
I don't have a x39 but my brother has one. A Model 1 sales upper and he seems to be impressed with his. Functions properly and kills anything he shoots. I myself am a Grendel guy.
 
Can i ask why you chose the carbine length gas over a mid length ?
Same here, when I went to buy, I personally found the barrel choices in this caliber to be limited. Ideally I'd prefer a mid-length 18" SS fluted barrel ... but I've yet to find one.
LOVE this AR I do!
 
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