This is my first post.  I am building a 20" varmint model strictly for medium range varmint shooting.  I will not be doing any rapid fire with it at all.  I've used the search function and got some but not all the information on building my own AR but still have a few questions:

First of all, I live in California so I am very limited in the lower receivers that I can purchase.  I just paid for a Sun Devil, CNC milled receiver. Is this a "small pin" receiver?

I legally have to have a 10 round magazine fixed into the receiver and so I was going to order a 10 round magazine from Bushmaster for this.  Since this magazine must be mounted in the receiver and will not be able to be removed without tools is this a good brand choice?  

Will a Bushmaster lower receiver kit be adequate to get the gun running and should I get it with a two stage match trigger or buy a single stage match trigger seperately ?

Do I care if the bolt and carrier are chromed lined, etc.?

I have a friend recommending a 20" upper kit from J&T Distributing.com that uses an air guaged Wilson stainless barrel, free floated handguard, etc.  It retails for about $120 cheaper than the Bushmaster assembly,  Has anyone heard anything good or bad about JT Distributing products.


Thanks for any help.

Lacking first hand experience with a lot of the parts you're using, all I can help you with is a little advice about triggers. If you're going to be shooting at a significant distance, having a match trigger will make that a lot easier. For a "battle rifle", a standard trigger is usually "good enough" (although I still intend to go the match trigger route in my AR at some point), but match triggers make shooting exactly where you want to, quite a bit easier. Nothing improves accuracy-especially for the $-as much as a really good trigger.

"Do I care if the bolt and carrier are chromed lined, etc.? "
IIRC, they are all chrome lined, where the gas rings go, or at least they should be, but as far as a totally chromed bolt & carrier gos, no it doesn't really matter, MAYBE it would be more corrosion resistant, but the military doesn't use 'em, so you don't need 'em. I just bought a M4 upper and the dealer gave me the option of a chromed B/BC at no extra cost, so I took it 'cause I know they cost more, incase I resell it I could get more money.

For mid range critter busting the air-gauged wilson 1 in 8 should be perfectly adequate for the task.  
I've never ordered anything from JT Dist, but they seemed like real nice folk when I met them at the last gun show.