Help me critique this build

[Skyfire1201]

I'm planning on building a full time suppressed pistol for my next gun. Since this will be the first time I deviate from a factory built upper, I want to get some feedback from all your pros and avoid typical pitfalls that only come with experience. I want to stick to known quality mil-spec parts from manufacturers like Colt, BCM and LMT to maximize reliability, while customize the pistol to be as short as possible.

So here's what I'm thinking of doing:
Upper:
BCM enhanced light weight 11.5" barrel, cut and re-threaded by ADCO to 10.5"
A direct thread 5.56mm suppressor, not pinned
BCM low profile gasblock
BCM upper and bolt
BCM KMR9 rail

Lower:
Aero pistol lower
Law folding stock adapter Gen 3
Blade pistol stock
H2 buffer

My biggest concern about this build is the barrel. I want to stick to a 10.5" chrome lined milspec barrel with NATO chamber, that will cycle reliably with or without suppressor on (someday I may decode to run a comp rather than a suppressor). I want to stick to BCM but they don't make a 10.5" barrel, so I got the idea of having ADCO cut it down to size. But will this create barrel length/gas port size mismatch that'll make the rifle less reliable? Also, will a ELW barrel running with a suppressor have overheat and premature wear issues?

Although I prefer to stick to a factory upper, I'm open to building one together from quality parts. What barrel will you recommend for my build? Also, are there any parts I listed that are known to be incompatible with each other?

Thanks in advance!

[Iraqgunz]

I'll add this to the upper/barrel dilemma. It sounds like you are building an AR pistol so as to not go NFA, that's fine I suppose. I would not go through the hassle of buying an expensive barrel and cutting it down. 1" is not going to matter since you are already using the folding stock adapter so just leave it 11.5". If you cut an 11.5" barrel down, the port will be too large. If you insist on cutting down to 10.5" then you might as well buy the 16" carbine barrel and then have the port opened to .071 (especially if you want it to work w/o a suppressor as well).

I am partial to the SIONICS NP3 BCG, especially for a suppressed AR. I also like the MUR upper and would probably get one of those if I was building another AR. Lastly, if you are using this un-suppressed/suppressed the H2 buffer should be fine.

[firefighter37]

Not sure what the intended purpose is, but your requirements seem like a perfect candidate for a 300 Blackout build.

[firefighter37]

Also, if sticking to 5.56, why not an LMT 10.5"?

[docsherm]

Also, if sticking to 5.56, why not an LMT 10.5"?

I was thinking the same thing.

[Iraqgunz]

Because an LMT 10.5" upper with an FSB will not work with a 9" KMR rail. It's obvious he is looking at something without an FSB.

I was thinking the same thing.

[bigjack7440]

Also, if sticking to 5.56, why not an LMT 10.5"?

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[Skyfire1201]

Thanks for the info guys! The LMT 10.5" sounds like an interesting choice, though I'm contemplating between having a fixed front sight or not. Where the front sight is on a carbine length is where I typically like to hold the rifle, and I haven't found a light weight rail that accommodates a front sight and fits a 10.5" barrel with suppressor. Also I'd like to go as light weight as possible, which means going with a LW barrel profile vs gov profile.

Iraqgunz, thanks for the tip on the SIONICS NP3 BCG, I'll sure look into it.

As to the 300BLK, I already have one in 9", and is looking to build a short 5.56mm carbine this time around.

[firefighter37]

Chopping a FSB is easier than cutting/rethreading. I would get an LMT 10.5", and chop the FSB, slide the KMR9 on and call it a day.

[grantoga]

Sorry to derail, but are the Law folders considered g2g for a defensive weapon? Reason I ask, I came across one and am debating putting it on a 300blk pistol with KAK tube and brace