First off, I am not a very experienced builder and shooter of the AR15 (5.56) platform, but I have learned a lot from members on this board and reading articles and watching videos on other sites.  There are a lot of conflicting info out there, and what I ended up doing was to do trial and error learning utilizing the information out there that made the most sense to me.  I have built a small number of AR platform rifles, and only have been shooting them for a few years, so I have a lot to learn.  I decide to write up my experience so that others, like me, can have some data points to use on their own learning.

I built a 10.5" SBR using very high quality parts, with the intent of building a very lightweight but reliable rifle.  Lightweight and reliable in the same sentence for AR15's seem not to belong based on the opinion of many people - some that have a lot of respect on this board.  But because I'm a knuckle head, I wanted to see for myself what all the issues would be to build such a weapon.  I've posted a picture before, but here is the rifle:



The important components are: BAD556-LW upper and lower receivers, BAD Ultra match  Lightrigid 10.5" 1:8 twist Wylde chamber barrel, Taccom LW Recoil System, Taccom reduced power spring, Faxon Gunner LW BCG, SLR Titanium adjustable gas block (0.625), Griffin Armament Titanium Minimalist Brake + Blast Shield.

Without optic and magazine, this SBR weighs 4 lbs 8.8 ounces.  The PA 3X Prism Scope weighs almost a whole pound, but I use it because of my eye sight.  I intend to use a Griffin Armament Recce 5 Suppressor when I get it out of jail.  The tuning experience is all without a suppressor.

After doing all the function checks with snap caps, and cleaning the barrel and chamber thoroughly, I took it to my rural property.  I have a 50 yard make shift range that has the side of a hill as a backstop (about 50 feet high above the targets I had set up).  I was using Wolf Gold .223 rounds to do the tuning, but also tried Federal (LC) XM193 and IMI M193, all 55 gr.

From fully closed gas, I opened the gas block two clicks.  Had one round of WG in a Hexmag 30 round magazine, and fired it.  I had an observer watching, and she said that the BCG did not move.  Not enough gas to even unlock the bolt from the barrel extension.  Snaked the barrel to remove anything that first round might have kicked out of the rifling, opened the gas block 4 clicks from fully closed, and fired another single WG round.This time she said that the BCG moved, but the fired case did not eject.  Snaked the barrel again, and opened the gas block 6 clicks from fully closed and fired another single WG round.  This time, the fired case ejected and the BCG locked back.  Now these 3 shots, I noticed how little recoil there was.  Even a lot less than a 16" mid-length AR15 which as most of you know isn't a heavy recoiling rifle in the first place.  I am very amazed at how this very light SBR is so easy to handle.  By the way, these first shots were fired using the blast shield.

I went down a click (5 clicks from fully closed), and a WG round ejected but the BCG did not lock back.  I went back to 6 clicks from fully closed, took off the blast shield (shooting now with just the brake fully exposed), and again the case ejected but the BCG did not lock back.  The blast shield added enough back pressure to lock the BCG back with 6 clicks.  Interesting.  So I loaded an IMI M193 round, no blast shield, 6 clicks open, and the case ejected and the BCG did lock back.  Tried a Federal XM193 round, no blast shield, 6 clicks open, and the case ejected, and the BCG did not lock back (same result as the WG).  I was snaking the barrel between each of these shots, by the way.

I was not shooting to evaluate accuracy (I'll do that the next time), but I did try to note how much my sight moved off of my aiming point with and without the blast shield.  First of all without the blast shield, there is a split second where all you see is the blast flames and feel the concussion, but the sight barely even moved from the POA.  With the blast shield, there is no concussion felt and no blast flame, but the POA does move slightly more (barrel rise and an odd small movement to the right - might be the shooter not the rifle).

I noticed a pretty good twang of the buffer spring.  So I removed the spring and greased it up pretty good with white lithium grease.  The receiver extension had dry lube on the inside.  This quieted the twang where I no longer could hear it, and it had the effect of locking back the BCG on both WG and Federal XM193 on 6 clicks and no blast shield.  This goes to show, that even the small amount of friction of the buffer system has an effect on the reciprocating movement of the BCG and buffer system.

So, I have left the gas block at 6 clicks open.  I am absolutely amazed at how flat this rifle shoots and the lack of recoil.  I had zero malfunctions (except for those shots that were deliberately under gassed).  I shot another 100 rounds or so, mostly WG, but shot a box of IMI M193 and a box of Federal XM193, and this rifle is a pleasure to shoot (with blast shield).  It's a great rifle, and I have no indication of reliability issues.  No popped primers, no case bulges, everything looks really good.  I'll have to do this all over again when I get my suppressor.  I am at 175 days in jail, so I am hoping two more weeks, max.

I hope my experience is helpful to those of you with low levels of experience like me.  If you feel I did anything wrong or could do better, please let me know, or build on this discussion.  Thanks in advance.

Looks like a smooth setup! And that is a nice looking rifle! Congrats and getting it to run well and best of luck on the suppressor clearing soon. I checked NFA tracker and it looks like they are clearing Form 4s from early March. Still waiting on my last suppressor too!

ATW!
-Fox

Nice rifle OP and nicely explained process of adjusting your gas block.

That grease will end up turning into carbon filled grinding paste.

Well, if you recall, it took us a lot of effort to get it all straightened out, but you guys delivered as promised and I couldn't be happier in how the BCG and bolt has performed in this rifle.  Thanks, Nathan.

ETA: The other side

OK, thanks for the warning.  Now I have to clean it all out.  I just looked at it, and with just those few rounds, it still is pretty clean, but I can understand your warning