We have recently purchased this gun. It is still in the box. It is a 5.56 rifle. According to the manual provided I can not find any where as to if it needs to be shot with 5.56 rounds for X amount of rounds for a break in period before friing .223? We are new to guns, very new. We are joining a gun club very soon and hope to learn more.
Thank you for any advice you can provide.
Jace
No break in necessary, especially before “friing” .223. Congrats on your purchase, welcome to the site & be safe. 
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It does not need to be specifically broke in first with 5.56. Just use good quality brass cased ammo and enjoy your new rifle. I would use cheap (inexpensive) Federal M193 or PMC M193 or what ever is available to you. Excellent choice for a first rifle. I would stay away from using Wolf/Tula ammo.
Thank you gentleman. This is all a learning curve for me/us. Greatly appreciated.
Jason
Excellent rifle! I have 2 and they have been awesome! BCM builds great stuff! You will only find it giving you trouble with weak .223 ammo. Like they said, 5.56 brass cased M193/M855 will function great! Enjoy!
Sparky
Here’s a link to cleaning and lubing your new rifle. Continue to read the stickies to gain more knowledge of the AR platform. Welcome to the forum.
https://www.m4carbine.net/showthread.php?35490-Basic-AR15-cleaning
It will run with 223 ammo just fine the most important thing is to keep it well lubed,look up the lube points, oil is a good thing. There is no need to wear out the rifle over cleaning it. It doesn’t have to be clean to run well.
Thanks guys. Thank you for the ‘cleaning’ link. It is much appreciated. We will continue to research and learn.
Jace
But then you don’t have to wear out the BCM by over cleaning ithttp://www.slip2000.com/blog/s-w-a-t-magazine-filthy-14/
Please stop saying “we/us” without further clarification of whom you are speaking; it’s creepy.
:lol: True, it’s reminiscent of Gollum from LOTR
But congrats on your purchase. You’ll get a lot of love on this forum for purchasing a BCM to pop your cherry. A lot of people get DPMS, BM, etc out of ignorance, so you’re a step ahead.
As everyone else said, just shoot it. You’ll figure out what it likes.
Please stop saying “we/us” without further clarification of whom you are speaking; it’s creepy.
LOL, I say keep going with it. It makes things spicy and unpredictable.