I know there is a topic for lightweight AR-15 parts, but I would like to have a really good discussion regarding the various components associated with a lightweight DI setup.  I would really like to hear from anyone with knowledge regarding setting one up!

I've got two aluminum bolt carriers, a PM&T Titanium, and AIM lightweights.  

They will work without adjustable gas, although you could run into problems if your gun is already overgassed with a standard BCG.  I run the PM&T with a 7.5" Voodoo barrel.  With a standard BCG it won't run as it's undergassed.  With the PM&T it runs like a sewing machine.  I'm using an adjustable gas key on one of the aluminum BCGs and an MGI adjustable gas tube on the other.  The AIM is being used with an adjustable gas block.

I'd recommend using adjustable gas to get the most out of a lightweight BCG, but it's not required in most cases.

I am a 5'-4" 110lb lady and I am setting up a lightweight good all around AR-15. I have started by selecting what I feel to be a good middle of the road weight, light BCG.  RCA's Titanium offering with the adj. gas key is the one I'm using for my very first AR build.  I selected this one for the fact that all dimensions for all intensive purposes are that of an M16 carrier.  Everyone seems to have differing opinions on how to set-up the rest of the components.  So what can everyone agree on? I would also like to talk about Bolts, Cam Pins, Ejectors, etc.. Everyone seems to sell an upgrade for everything that is part of the BCG, its confusing.

I would like to make well informed choices and not expensive mistakes!

Quite a few people say to use JP's SCS for the buffer with the LW BCG, and that it makes a huge difference over the other choices. What about all these enhanced this and that everyone is peddling? Anything worth it?

Yes it can be confusing.  When it comes to the BCG, you have two main parts and that is the bolt and the carrier.  The bolt sees the high pressure from firing a round so bolts are typically steel.  You want to stay with a reputable manufacturer that makes the bolt from C158 steel or 9310 steel.  The components like extractor and ejector parts see as much high pressure so staying with the bolt's manufacturer parts is good.  BCM and other reputable bolt manufacturers sell bolt rebuild kits that replace worn out parts like gas rings, extractor, ejector and their springs.  Cam pins are high wear parts, but buying one made from some exotic material doesn't save you much weight and will cost a lot, same for firing pins and retaining Cotter pin.  So I would just stick with the components that come with your RCA BCG, they make good stuff.  If you are going for the lightest possible weight like some do, you can spend a lot of money on titanium cam pin and firing pin and that will save a few grams.  Not worth it IMHO.

I have a build that uses a JP polished stainless LMOS BCG in conjunction with their Silent Captured set-up and a Syrac Adjustable gas block.  The recoil is almost nill and is superb for follow-up shots.  I'm a believer.

I have no experience with the SCS, I've heard good things though.  Stick with standard firing pins, Ti is a poor choice for firing pins.  Cam pins, a standard one will work fine.  I use a hydra fire roller cam pin in my aluminum BCGs, standard in the Ti and steel.

Stay away from the Sharps enhanced bolt.  Other than that, the various enhanced bolts are marginally better than a standard milspec bolt.  Up to
You to determine if they're also worth the additional cost.  If you're using a carbine or pistol gas I'd get something like the LWRC, if you've got a mid length or rifle length then the benefits of an enhanced bolt are less important.

Seems that the 9310 steel gets a lot of praise as a big upgrade over the mil spec C158 as far as bolt material goes. I could not be happier with my decision to go with the RCA BCG, it really is immaculate. The bolt is of 9310 with an excellent finish and a laser engraved logo. The firing pin and cam pin has the same exquisite finish as the bolt, and I will be buying extras to keep on hand. Should I have any other parts for the BCG on back up?  Also, are the JP one piece gas rings a worth while investment?  

Thank you so very much for all the great info!

Do you know where a good place to pick up one of the JP SCS setups for a good price? Good grief they are expensive!!!

Honestly, if you just buy a spare bolt, you'll be covered.  If you just want to buy parts, a bolt rebuild kit would be fine.  Having a spare firing pin (because they can get damaged easily), a retaining cotter pin (because they are easy to lose, an extractor and extractor spring (because they wear out), and the extractor pin (easy to lose), and the ejector spring (wear out).  I don't have experience with the JP single gas ring.  Standard gas rings are fine (wear out).  To test your gas rings to see if they are worn out, extend the bolt in the carrier and set the BCG on a flat surface bolt face down.  If the weight of the carrier causes the bolt to move back into the carrier, your gas rings should be replaced.

Keep the bolt (and lugs) and bearing points on the carrier well lubed, (and clean) and it will last a few thousand rounds.

There is debate whether C158 is better or worse than 9310, but as I understand it, manufacturers are moving towards 9310 because its a bit easier to manufacture. I believe that C158 is specified as Mil-Spec.  I have both and from a function and reliability perspective, I can't tell the difference.

There are a few hyped things about cam pins.  Like I said, it is a high wear part.  POF roller cam pin, V7 radiused cam pin, etc.  Some of these make sense mechanically to offer some benefit, but I wouldn't go out of my way to buy them.  Up to you.  It's part of the fun with messing with your AR.  You experiment and find out what is pure hype versus real benefit.  You're doing it right, though.  Do a healthy amount of research, ask questions, and experiment.  And be safe but have fun!

Thank you! I have seen a lot of mixed stuff on those Sharps reliabolts, they seem to be trying to fix a nonexistent problem. Just from what I've read!

Just posted the second part of my review on the RCA Titanium BCG w/AGK!