I really like the BCM SS410 barrel. I like th ecomplete upper, but I don’t know that I’d eve use the 12" of rail real estate. I’ve considered just buing the barrel and slapping a DD 10" rail on it. The thing is I’m guessing that the BCM proprietary build is superior. So, for those of you with a BCM complete Upper w/ 12" rail…how’s the balance of the rifle. If the 12" makes for better balance, and not too much weight than I’d prefer it. If it throws off the balance and is really only useful if you need the space for accessories, than it’s a no go for me.
i have 16" middy standard barrel with a 12" rail using an Magpul ACS stock and it balances well. I would think with the heavier SS barrel you might need something like a UBR or A2 stock. The difference b/t a Lite 10.0 and an Omega or Lite 12.0 is around 2.5-3oz according to DD website.
The Daniel Defence OMEGA & OMEGA X rails are TITS! I just put a 9" OMEGA X on my SBR and I will never own another rail. All my guns from now on will have the OMEGA rails unless its a really, really thick barrel…Hell even if it is I would try to make it work some how. My buddy just put a 12" Omega rail on his 16" middy and it’s SUPER light to have that much “rail” estate. These rails are extremely light and skinny. I can’t rave enough about them, just go get one and you will fall in love.
I would suggest the 12.0 rail, the weight difference is going to be minimal, however the extra 2" of rail makes a big difference (how the carbine feels if you like to get your hand further out on the forend, amount of real estate you have to rest the gun on a barricade, etc).
For a SS410 with a 12.0 rail I would suggest a stock with a little more weight, like a Vltor EMOD or a Magpul ACS or UBR.
These two articles may be helpful:
03designgroup | [b]AR15 Upper Receiver Weight Comparisons 
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03designgroup | [b]AR15 Buttstock Considerations [/b]