I got a great deal on a complete BCM upper - minus the BCM BCG.

there is a no name, but also new, BCG inside. I ordered a new BCM BCG just now. But i was thinking of shooting the rifle this weekend while out of town, but was wondering if this would be foolish since i will definitely be putting in a new BCG next week?

What are your thoughts? I will have access to a really good range this weekend which is why i would want to shoot, but it is an investment so whichever the smarter choice is....

I never was in a situation like this with a build

You plan to keep both BCGs?  If so, game on.

definitely keeping both BCGs. But the BCM will go in as soon as it arrives and the mystery BCG will enjoy the view in the spare parts box. Thanks for the advice! ready to bust a few " caps" , if you will

I'm confused, why would you not shoot it?  Just because you have a no name bcg? Who cares!

haha, just because i have never just shot a new rifle, then switched out BCGs. I know headspace isn't really an issue in good parts manufacturers from what i read, but it just... feels... weird

Oh gotcha, I wouldn't worry about it.  BUT... headspace Guage/ go/ no go gauges are never a bad idea.

what brand would you recommend? there seems to be quite a few

Forster

Mine is a Brownells/Forster.  With modern manufacturing techniques, I understand that 223/556 head space issues on new equipment should not be a concern.  However, I check each one of mine.  Small price to pay in labor and money to ensure all is well.

I believe a larger issue is 223 vs. 556 chambers.  Due to some smaller dimensions (223 leade specifically), shooting 556 ammunition in a 223 chamber causes significantly increased pressures.  All five of my barrels are marked as 556 but only one- a BCM BFH, measured originally as 556 with the rest as 223.  The other four barrels are less expensive and I easily reamed to 556 specs to be safe.  In the end only one of my barrels was out of spec enough to possibly cause issues (an old Bushmaster), indicated by the amount of material on the reamer when it had completed its job, with the other out of spec barrels just needing a bit of a touch up to be in spec.  YMMV.

I use the .223/5.56? gage of Ned Christiansen for checking:  http://m-guns.com/tools.php