Im not going to lie but this is my first ar build 5.56. Tax stamp waiting at the moment. I have shot plenty but never built my own.  My plan going into this was to build a very light weight AR with low recoil.  I have a Geissele 10.5 inch barrel so I know enough that it will be a little more violent with the gas.
So my question is I was thinking a low mass bcg middle range like 8oz give or take and a SLR gas block and an adjustable buffer kit to get it all timed right but I wanted to get the experts opinions on that combo...  
I understand that a low mass carrier will not be as strong as a full bcg and a heavier buffer which is what my friend did but I still would like to go light weight.  I will not be shooting 5000 rounds through this gun but I'd like a gun I can take out every now and then and target shoot and not something built for the apocalypse.  I'm going to build another gun for that next.  It was more of how light can I make this gun.
But the main thing I question is if i should even run a low mass in a 10.5 inch barrel and do people even do this because I assume its made for longer barrels?
Before I spend 3-4 hundred on something that will wear out quick.
Thank you and sorry if I'm wasting your time...

The lighter you build your rifle, the more recoil you will feel.

It'll take a very efficient brake to help tame it, and to a certain extent you can try to spread that recoil out with a very strong spring to slow down a lightweight BCG, and cushion or spread it out with a cushioned, wide contact area buttpad.

If you want light *and* low recoil, you'll need to customize your ammo.

thank you for this information.  I can look more into that but now I have a place to start.  A heavy spring is a great idea.  I know I will never achieve minimal recoil but the plan is to get it as low as i can with that barrel.  Muzzle brake I havent decided on yet lots to choose and I have learned so much in such a short time.  Brain hurts.  Nah im just kidding I wish I got into it much earlier in life now im 39.  Any suggestions on a good brake...  I can look up reviews and what not but Id like to know what others think as well...

After a decade of collecting and building and constantly learning: Do yourself a favor and put this idea on the backburner for now and just build a basic but good goto war rifle first. Save everything extravagant for later.

Aero, BCM, whatever mid grade lower, colt receiver extension, USGI action spring, h2 buffer, single stage colt trigger. Learn to install a lower parts kit, the SOLGW starter lower parts kit is your best bet for quality/dollar spent.

Colt, BCM, DD, Aero upper receiver, whatever has M4 feedramps, whatever charging handle, toolcraft bcg, colt or dd barrel with a FSB or without and learn to install a lopro gas block, whatever muzzle device, Knights RAS handgaurd or a DD RIS FSP or a Midwest rail or a Centurion. Something basic but GOOD

Tools youll need:
A 5-6" vise, a midwest industries upper receiver rod, pilot punch set, pin punch set, brass pin punch set, 1/2" torque wrench, magpul armorers wrench, 8oz brass/rubber mallet, and the forward controls muzzle wrench and castle nut wrench are also great. Get an SLR gas block dimpling jig and at least one 5/32 Titanium-Aluminum-Nitride drill bit from Mcmaster-Carr for dimpling.
(You might as well invest in high quality tools now before you ruin a bunch of parts learning that you need them later.)

Also for assembly get a good amount of homemade gun lube on hand (full synthetic mobil1 0w-20 + grease works great) for lubing new builds. Less is not more, just keep it out of the chamber.

Figure out how to build a basic rifle first and go from there. I guarantee your taste will change and/or your preferences will develop to be more refined. Take it from someone who has blown shittons of cash on builds that have no idea what they want to be because I had no idea what I wanted them to be because I had no idea what I was doing.

A low mass carrier is not going to wear out faster. After almost 20 years of building AR’s all my personal builds, in a myriad of calibers, and including SBR’s which are all suppressed, I use low mass carriers. Control the gas and you’re good to go.

Your right I wish i had come here much sooner.  The problem is Im only a muzzle, bcg and spring away now...  I would have been done by now but with the ammo situation the way it was I decided not to rush and take my time...  Im more of a computer nerd to be honest but I was also thinking if I dont like something I see it as extra parts might as well build another like computers...  At least thats how I justify it with wifey.  My military friend just finished his SBR and its is really nice with his eotech and silencer and I enjoyed shooting it...  So I wanted something very similiar but I wanted to reduce as much weight as i could incase I add an acog and a silencer later on...  I doubt I can start over with a new build just yet.  The only real difference we have is 10.3 barrel vs 10.5 barrel and a low mass bcg that i was planning.  Maybe i will just get a full bcg for now.  Prolly find one in stock much easier.  I can always switch them out later when I build my second AR.  I really only want 2.  I do appreciate all your recommendations though.  Just wish I came here first.  Live and learn.

@chewbacca,  Can you recommend a spring and buffer.  I was thinking about the adjustable buffer kit so I can see what size works best by adding weights.  Instead of just buying random buffers...  My pal on 10.3 barrel and full bcg used an H2 buffer but that was without adjustable gas block..  he uses a Geissele super block on his.  I plan on an adjustable gas block on mine though.  Glad to know someone uses that set up.

I want to take the time to Thank you all as well.  I was really hesitant to post due to the backlash I was expecting or people wanting to troll.  However I am glad I did.  So far everyone here gave me alot to think about and great advise.  So thank you again.  Glad I joined.

I use most often a JP carbine spring and standard weight carbine buffer. I have used wolf XP and tubbs flatware springs too. Using a heavy buffer defeats the purpose of a low mass carrier. Tune the gas and you’re good to go.

my thoughts exactly.  Its counter productive.  Nice now I just need to find them in stock and wait for my stamp to arrive.  appreciate the recommendations.

Tuning the gas does nothing to mitigate your primary recoil impulse, which is the bullet being pushed out the bore. Pretty much only a muzzle brake can reduce it and extra rifle weight can change how you feel it.

Tunable gas does let you put just enough force into the BCG to cycle properly, though. Bottoming out in the buffer tube during counterbattery, and slamming into the breech when chambering can be minimized, so you get the least amount of secondary and tertiary impulses possible.

I was worried about chambering and timing with a low mass.  seems an adjustable block would fix that.
At the time I was also thinking about the bcg moving in side that if it is heavy it would produce more recoil.  
so thats when I thought lighter would be better. You suggested a spring to soften that up and is now the current search...  Ive been looking this whole time to see what others are using just not finding alot.  Do you not think JP spring would be sufficient?  Ive never used one.  Just interested since another SBR user uses them.
I do know because of your advice that a good muzzle brake is required since im at least a year out for a suppressor.
The only thing Im weary of if I have to go with a heavier buffer on a low mass then it will weigh the same as if i just went full bcg.
am I wrong that a full mass bcg would cause a bit more recoil?  As above user said I should have built a standard rifle first but im already down this rabbit hole.

You're not going to want a brake on that...at least not for long.

You're probably going to want to suppress it at some point...because it's going to be obnoxiously loud.

awesome   that was very informative.  I did some research on brakes as i was told to get a good brake and the smc was the one that caught my eye...  There was another one called Precision Armament Hypertap Muzzle Brake.  I will go with smc.  I plan on a suppressor asap but from what I gather it takes 6 months to a year.  The plan was a thunderbeast dominous suppressor however I havent done much research on them yet so that can change.  As for now with everyones help here I can get this build done and order a suppressor end of the month.

Go ahead and put a brake or flash hider that works for the suppressor you are going to buy. It will save you money not buying a useless brake. Every time I end up near someone at the indoor range with an unsuppressed 556 sbr I am reminded how much I like my suppressors. It would be really unfortunate to have to use that gun in a self defense situation indoors. You will likely suffer some degree permanent hearing damage.

1. A low mass carrier will not increase recoil when paired with an adjustable gas block.
2. A low mass carrier is not "weaker" by any meaningful standard. It won't wear out. It won't break.
3. 5.56 ARs don't have much traditional "recoil" and the muzzle jump is primarily the result of reciprocating mass. Controlling that is what you are after.
4. All you need is a JP LMOS carrier, JP polished spring, and a 3oz standard carbine buffer to get your adjustable gas block to give 100% accuracy and reliability while minimizing recoil in my experience. This works suppressed and unsuppressed.
5. A lightweight 10.5" carbine starts with a lightweight barrel and rail. Your barrel should be under 20oz at 10.5" inength. Your rail should be under 9oz with all attachment hardware and barrel nut.
6. You do NOT want a brake on a 10.5" barrel. It will be the most annoyingly concusive thing you could imagine and impossible to use without hearing protection indoors. Use a flashider suppressor mount.
7. When setting up your adjustable gas block DO NOT add any clicks for reliability. Your spring will wear, your gas block will seal with carbon, your gas port will erode, and your gas rings and wear points will polish up and improve reliability in the first 200 rounds anyway.
8. If you have a LPVO you will have PLENTY of mass to tame recoil on a lightweight gun. If you have an optic, a light, and a can you will have way more than enough weight even on a sub 5 pound rifle before the can.

Low mass BCGs are a gimmick.  No military gun uses them.  Keep it simple, use heavier buffer.