AR 350 legend build

[Lo-Profile]

So I'm building a 16" side charging 350 legend AR. Mostly because I don't have one and ammo was available at Walmart.
My upper of choice is coming with a BCG and charging handle. Already have a lower built.

What else do I need to know about these. Will my 10 round metal USGI style magazines work with this. Have read there's issues with poly magazines

 

[maxxhavoc]

So I'm building a 16" side charging 350 legend AR.

I assume it is a BCA - I went with the 20" A friend went with the 18"

Mostly because I don't have one and ammo was available at Walmart.

I got mine just for fun with reloading. It should be interesting playing with the caliber.

What else do I need to know about these. Will my 10 round metal USGI style magazines work with this.

No. Get some specific 350 Legend Mags. The front ridge is the same as the other 2 on these. BCA recommended CMMG. I do not see any difference except branding between CMMG and Duramag. Supposedly, you can file down the front ridge in a Magpul AR mag.

I have heard they get rather reliable after they break in. I am getting feed issues, especially with Hornady Whitetail ammo. Winchester 147s work the best. Others have also recommended magazine lip changes.

 

[jmorris]

So I'm building a 16" side charging 350 legend AR. Mostly because I don't have one and ammo was available at Walmart.

Nothing like a good reason, beats an excuse after the fact every time.

Post photos and a results when you get it to the range.

 

[Skylerbone]

I had magazine issues but with a bolt rifle using AR mags (Duramag). My solution was filing the front edge off.


CMMG magazine, I don’t have any so I took a screenshot.


Duramag, another screenshot.


One of my Duramags, unaltered. Note where brass hits front of magazine before round can tip up into place.


One of my Duramags after alteration.



I'm fairly invested in 350 Legend at this point, living in a straight wall State, with 3 rifles chambered for it. Good performance and reasonably priced outside the current panic. Should be plenty fun in an AR.

 

[beagler]

Here is my BCA at 100 yards using Win xp. The 180 soft points were all over the target. The small holes are from my 5.56. I have had the best luck with Wilson Combat mags fwiw.

 

[beagler]

Anyone that built a 350, what muzzle devices are you using? Will any 9mm device work?

 

[CarJunkieLS1]

My 350L upper took some doing to get it to reliably function. I judiciously polished, dremeled, and polished again feed ramps and chamber. The mags never did feed exactly right even after modifying them like shown above. I actually found for me that the best feeding mag was a 10 round standard 5.56 PMAG. I dremeled the strengthening ribs off both sides and then used sandpaper to smooth it out to make sure the follower didn't bind up. Once that was completed the rifle feeds and ejects perfectly, and doesn't dent up my Starline Brass.

 

[earlthegoat2]

I use CMMG mags in an AR with perfect results.

 

[Walleyewarrior7]

If you hunt with it please dont use the 150 grain Winchester’s.

 

[CarJunkieLS1]

If you hunt with it please dont use the 150 grain Winchester’s.

From what I've seen the 180gr Soft Points from Federal and Winchester have been consistent performers. And I personally use the Hornady 170 Interlock and haven't had issues on paper or on the one deer I got with it.

 

[euclid]

I have found that reloading for the 350 Legend allows me to correct for what I believe to be the main reason some people suffer mis-feeds: The OAL is too short.

Factory offerings measure 2.15” - 2.20” and don’t feed well from my CMMG 5 and 10 round magazines. When I reload I set the OAL to 2.30” and have never suffered a FTF. If the factory loads would emulate this, there would be far fewer reports of mis-feeds, in my view.

 

[euclid]

I’d like to add that my reloads print 1 MOA groups from a Bear Creek 16” upper with ballistics that mimic a 30-30 from an AR-platform. Not bad.

 

[sequins]

I too see 350 legend ammo available on otherwise bare shelves and have had to banish this thought in the past.

I hope you enjoy your rifle!

 

[citizenconn]

I also have had good luck with CMMG mags in my 350 ARs. I recommend the 170 grain interlocks for deer.

 

[mavracer]

I've gone back and forth since it came out, add to that I have a Torrent T9K that's rated for 300 Win Mag. I had myself talked out of it as I have a SBR Blackout and a 450 carbine til this weekend. Another thread had me lookin at stuff and Cabela's had ammo reasonable and I had some points to burn. Now I have a bolt, barrel, mags and a suppressor mount ordered to convert the 450.
I'm gonna sell the 450 Barrel and bolt, but I'm keep in the dies and brass for now maybe a RARR is in the future.

 

[mavracer]

If you hunt with it please dont use the 150 grain Winchester’s.

Why if you don't mind?