AR help please

[IMR4320]

So after a long time of looking I finally got(although still waiting for ATT) Core-15. I did my search so picked the one chambered in 5.56 so I'm not restrained to .223 ammo only and I also knew it would have 1:7 barrel twist which leads me to believe it should like heavier bullet. What ammo do you guys recommend and how much accuracy will I lose by shooting .223(55grn. FMJ). Also, I picked up an extra Magpul Pmag and and XCR. I know there are plenty of other brands, probably not all of them great. What mags do you recommend to get and which to stay away from ?
Any other usefull tips would be welcome, I own many different guns but I'm new to AR.
Thanks

 

[North60]

Pmags work great,lots of sponsors have bulk packs on sale right now. You can also get the LAR pistol mags ( hold 10 rounds) and perfectly legal. I almost bought a Core rifle seem to be good guns at a decent price enjoy..

 

[LeeEnfieldNo.4_mk1]

I hear great things about the D&H steel 5/30 round mags. and Pmags are a pretty good choice as well, and are quite common and priced not too badly, although some of them are riveted to exactly 5 rounds instead of the preferred 5.5, so the fifth round is right tight so no inserting on a closed bolt.

As mentioned, their are the LAR 10 round pistol mags. ATRS out of Calgary is selling 20 round length polymer versions that have been received quite well by users.

As for other tips, only one I can think of right now is that an AR likes to run wet, so don't go too stingy on the lube.