My AR-10 358 Winchester project reached the functional stage late Saturday after I got back from France.  I was able to take it out on Sunday for a 20 round function check, which it passed with no hiccups.

The basic specs:

Lower Receiver:  TN Arms AR-308 lower
Lower Parts:  Nothing special mostly.  DPMS, PSA + some V-seven titanium take-down and pivot pins
Buffer/Receiver extension/Stock:  PSA 3oz buffer (AR-15), PSA PA-10 Receiver extension, Generic collapsable stock
Upper Receiver: Fulton Armory Titan side cock standard profile
BCG:  vSeven Titanium BCG
Barrel:  KAK Industries 16" 358 Win Stainless
FSB:  Fulton Armory FSB .750"
Gas Tube:  Brownells
Generic thread protector on the muzzle
Free Float Tube:  DPMS, kinda
Rear Sight:  Magpul MBUS

I get that AR-10 is not a standard.  The is a DPMS pattern 308 AR style rifle build, and I will use AR-10 throughout.  Sorry if that bugs anyone's sensibilities.

The main goal of this build was under 7lb with reliability.  To that end I used the TN Arms lower, which is about half the weight of a standard AR-10 lower.  Next big place for weight savings was the bolt carrier group.  I went with a titanium BCG, which weighs about 12 oz including the bolt. 

Last big savings place was the front grip/free-float tube.  I ordered a DPMS carbon fiber tube in carbine length, then didn't like the look or that it left a solid  2.5" of the gas tube exposed since it is a mid-length system.  So, I ordered a section of of 6061 T6 aluminum tubing from online metals and pressed it onto the barrel nut that came with the DPMS carbon fiber tube. Ended up the same weight as the carbon fiber one after I cut it to length.  It clears the back of the front sight base by about 1/16" of an inch.  To install it I used some leather the pad the rifle, a pipe vice and the Brownells torque tool that goes in the upper receiver and engages the locking lugs in the barrel extention.  Took 45 ft-lbs of torque to get the holes aligned for the gas tube.

Final weight Saturday night was 6lbs 11.9 oz.  The photo I have is before I installed the gas tube, bolt catch and thread protector on the muzzle, which apparently weight a bit over 3 oz.



The gun in it's final form:



I have an NOE 310 grain .360 flat nose mold that comes with HP pins.  I cast up about 50 last night.  The should weigh right at 300 grains once powder coated.  I plan to load them up in front of some BLC-2 and give them a test this coming weekend.  Then more function testing. 

So far I am really digging this gun.  It does have some punch when shooting it, about like a Mosin Nagant or M1 Garand.

Pretty sweet


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.308 necked up to .35 cal... in a Semi-Auto, AR platform?
 
Yeah... I dig that. 
 

Based on my experience, it should be a relatively easy project.  There are a ton more barrel options for the DPMS pattern AR10 platform in 338 than I found in 358.

And, you could play around with the really big 338 bullets like the 285 ELD loaded subsonic.  That is one thing I miss out on with 358 is big high BC bullets.  NOE has cataloged a 280 grain mold spire point mold, but it is not in stock, I don't know if they plan on any additional runs and even if they did it still isn't a boat tail with a super high BC.  As a result, a 338 in in my plans.

In fact, once I wring this one out and have it thumping with NOE 298 grain HP thumpers reliably, then I plan to build 243, 260, 7mm-08, 308, 338 uppers as well.  I have gobs of 7.62 brass to re-form into whatever I want, so I figure a whole family of AR-10's for all the 308 family of cartridges can only be fun!

sqlbullet... thanks for the post..... Im new to form, was searching high n low for info on building a .358 win ar10. I have been around weapons all my life but i consider myself a novice still.  I got bit by the ar bug. I am building a .358 win, I have McGown Barrel, and Aero precision receiver.  Im searching for a BCG, a .308 bolt will work ok ? I dont need a cal specific BCG ? I know my 6.5 creed I had to get a 6.5 bcg.  any and all help, ideas and so forth !

Thanks in advance.....   Billy

Watching this...interested in how the TN Arms lower holds up.  I have one (from the Oct '16 pre-election stocking up) that I haven't built on yet.