Alright, I’m on my first build and have my BCM 16" middy ready-to-go. But I still need the lower. My goal is not to buy another lower for a bit, and just slap on new uppers. Therefor, I’d like it to be top-notch. Here’s what I have so far:
-Mega stripped forged lower receiver
-BCM stock assembly
-PSA LPK w/o fcg
-Geissele SSA
-BCM grip, Mod 1
Anyway, I’d like to hear from you guys what else I could add to make this lower absolutely first-class. Thanks.
-Aiden
You don’t need anything else in reality. I assume the BCM stock assembly contains all the parts; receiver extension, spring, buffer, castle nut and endplate? I’m not a big fan of the BCM basic stock. I’d be looking at a B5 Bravo.
I think that an Vltor A5 extension, buffer and spring setup is superior, especially when combined with a B5 Bravo or Sopmod stock. Good luck getting any Vltor A5 parts any time soon, though.
I would get a BAD CASS-SA ambi-safety.
I don’t dick around with oversized mag releases, KNS pins or BAD levers
Why did you post this in general and technical discussion?
I do like the parts you listed. And agree the Sopmod is really nice. Or IMOD with clubfoot
Ambidextrous selector, qd end plate, magpul bad lever,
And dont forget the custom engraving that says “kick-ass lower” 
don’t post the same question in multiple sections, please.
I don’t know where you’re from, but if there’s a company within your state that makes a solid lower, you should get it from them.
When people ask you who made it, you can say ‘The guys in town.’ I always thought supporting your local AR manufacturer is bad ass. Especially if you’re from Colorado, then you can posses an Iron Ridge with pride.
But you said you have a Mega lower, did you mean upper?
No I think he means how to trick out his lower he already has
Honestly, if you wanted something that was just top top notch and had everything you would ever need (and perhaps will never need) I would tear up b/s/t forums and look for one of the ambi offerings from KAC or AXTS. We are not going to critique your choice of grip since that is purely user comfort. What comes with the standard BCM stock assembly? Standard A2?
hmm. well shit, this question is kinda in eye of the beholder for function, ain’t it?
MFT Minimalist Stock if you have Harry Potter arms.
UBR Stock if you like a workout while firing.
And no KNS for the SSA, there have been issues.
If you’re ambidextrous then anything ambidextrous will make the lower kick ass to you.
I’m just saying because if you only want one lower, it should really be tailored to you. I have another lower that has ambi controls that’s not for me. It’s so when my dad visits (he’s lefty). If this is going to be your one and only, make it for you brother.
Considering for rapid firing or classes, get the stuff that you believe will help you shoot it best, and not what we think is pimp…but I do make excuses for myself out of function to get the cool shit.
I would get a B5 Bravo stock over the standard- cost is minimal. I would also get a Battle Arms selector lever and Troy ambi magazine release.
Your plan is similar to mine as far as wanting one top notch lower to interchange multiple uppers with, so I thought I’d share my build plan. Whether you want to copy any of it or not is entirely up to you.
Lower Receiver: Seekins Precision SP15
I’d say you’re good to go with the Mega. I don’t have any experience with them, but I’m told they make an excellent product. In my mind, a lower is a lower, as long as it’s made to spec, forged 7075, and Type III Class 2 anodized. I looked long and hard at the Mega, but bought the Seekins for two reasons. 1) It was in stock. 2) I like the way it looks.
Lower Parts Kit: Either a PSA or WOA + Geissele SD-E
I’m not yet decided on which parts kit I’m going with, but I know I want one sans trigger assembly. I would buy from Grant but his have been out of stock since I started looking, and don’t appear to be coming back in any sort of timely fashion. That pretty much leaves me with PSA or WOA… I’ll probably end up flipping a coin. I’m also considering sending off the major components to have them nitrided (not the springs/detents/pins, just the selector, catches, takedown pins, etc…), and my wife is left handed so I may end up swapping out the selector with an ambi version, although I haven’t looked into it much yet. The trigger will be an SD-E, and that is only because I want the flat trigger bow and one of the uppers will be a semi-precision setup. I trust you’ve done your own research and decided the SSA is best for you. To round out the LPK I’ll be swapping the trigger guard with a Magpul Enhanced and the grip with a Magpul K2 or a BCM Mod 1 if I get impatient.
Buffer System: Vltor A5 w/ Magpul ACS Stock
My research has convinced me that the A5 system is far superior to the carbine buffer system, so I’ve decided to absorb the extra cost for the added benefit. I’ll be starting with the A5H4 buffer (heaviest they offer, with 4 tungsten weights) and swapping in steel weights from a standard carbine buffer if I need to lighten it up. Due to the added length of the receiver extension, I’m going with the longer ACS stock. You can never have too much storage space IMO… Even if you don’t see a need for it now you’ll have it later if you ever do. A Noveske QD end plate finishes things off.
Anyway, that’s what I came up with for my “one size fits all” lower, YMMV. I would recommend looking into the A5 system though if you haven’t already, and definitely this:
On the right hand side of the magwell. 