Hey guys,

I would really appreciate some advice on a build I'm currently pursuing.  Each of my first two AR builds are in good shape now, but I definitely made mistakes and wasted money. With this gun I'd like to get it as right as possible on the first go.

What I'm building:

300blk SHTF SBR

Buying Larue Ultimate AR Kit.
12" 300BO Barrel
10.5" handguard

Planned on selling Larue gas block and going with a superlative arms bleed-off adj. gas block (DI).

1st ?:
Sup arms is working on a piston set-up for 300BLK.  Assuming they are able to create one which can shoot subs and supers reliably, would you recommend a piston set-up for SHTF?
I really like the thought of a piston gun, but in my head, more parts = something more likely to break + the parts would be very difficult to replace.

Next ?:
I think the longer barrels seem to function more reliably.
But I was thinking about doing a 10.5" barrel (I would sell the Larue barrel and buy a barrel of similar quality).
Yet if the 12" barrel gets noticeable more reach, I'll be happy with the 1.5" of extra length.
So for people with experience with 300BO: it seems like 9.5-10.5" are the most popular lengths.  What is your recommendation here? 1.5" longer better for piston?

Next ?:
It seems like light-gray is the best color to avoid detection from night-vision.  Yet large, solid-color options are not as good as something with variation.
Well I could order the Larue kit in UDE cerakote (light-gray, costs $99 more).  Or, I could have the entire SBR cerakoted (including barrel, suppressor, and buffer tube) with a digital camo pattern consisting of three light-gray cerakote colors.  That will cost me hundreds more.  I would also maybe like how it looks more.  Thoughts here?  Is that just a huge waste of money?  Or potential benefit?

Last ?:
Is the echo-arII reliable enough to be a SHTF trigger?

Thanks everyone.  Appreciate any feedback.

I've had my 300blk 7.5 sbr for about 2 years now. Couple thousand rounds through it. I can honestly say you will never need a piston system for the 300blk. It has been 100% both subs and supers on a pistol length DI system. Only thing i need on it is an adjustable GB for when I run the can (AAC 762SD). I'm willing to bet an ADAMS ARMS piston system will mount up fine to your 300blk if you were dead set on it.

In regaurds to bbl length I suggest going with 9-9.5in. My 7.5 sending subs downrange is not quiet enough to extend them out as far as i'd like. However, the reason I built it was for cqb/HD. Running a TROY PDW stock on it with the can makes it a sweet little package with plenty of stopping power.

I cerekote myself. I went with Tungsten grey on the recivers/hg. Running a MI 12inch HG with my suppressor integreted. Thing is dank af.

*EDIT*
Just re-read your part about the echo trigger. LOL If you can afford the ammo, go for it.

Thanks for your response.

Yeah I suppose I should mention this would also be my main home defense gun.  So it'll have a real purpose even if the world doesn't end, lol.

The shortest the larue handguard goes is 10.5".  Makes me think I will probably buy a sup arm adj. gas block + sell the larue barrel and then buy a 10.5" barrel.

Appreciate your feedback.

Anyone else feel free to chime in!

Tried to upload a pic but file size is too large. Shucks.

If you use a bleed off block, it may be louder to bystanders than DI when suppressed.  Higher pressure gas venting out of the block vs lower pressure at the carrier.
Similar to POF systems or my RFB.
Most of the crud that ends up in the receiver when shooting suppressed is coming through the chamber after ejection anyway.

You had me curious until I read piston, and then Echo trigger?

So would you recommend a different gas block?
I like the thought of not having gas in my face as much!

Ha I just snagged one in case they get banned.
I'm leaning towards NOT using it on this rifle, but thought I'd ask while I was asking other questions.

Also the ar2 echo CAN be used with piston, fyi.  I know the gen 1 couldn't.

I haven't found the need for adjustable gas blocks in 300blk as long as the barrel port isn't too large.
If you have a barrel that's overgassed, then you can go with any standard adjustable block.  Set it to just lock back when shooting subsonics unsuppressed and it will function in any configuration.

You're going to get gas from the port and charging handle when shooting suppressed, even with a piston.

Okay, just to be careful I'll go with an adjustable gas block.
Would you recommend the SLR one since it doesn't bleed forward - and hence may be quieter?
I have the SLR adj gas block on a 223 ar15 and really like it.  Only reason I was going to go with another brand was thinking bleed off forward would be better for suppressed.

6 of one, half dozen of the other.

As mentioned earlier 9-9.5" barrel is nice go-to barrel length that will give you a good all-around range of use with a variety of projos.

I have a PWS Mk109 in 300BLK (9.75" barrel) that utilizes a non-adjustable gas block. I would recommend building your lower how you want and slapping on a PWS MK109 Mod 1 if you can find one available in 300BLK. Otherwise they are now making the Mod 2s with an 11"  barrel.

I also run a 9.5" barrel on an integrally suppressed DI upper with a basic adjustable gas block. Once tuned to the ammo I will be using it will be a "set and forget" adjustment as I expect little to change in terms of performance since the suppressor is perma-attached to the barrel.

As far as color, a full cerakote can run you ~$200 if you find one local. It doesn't seem like money is a limiting factor for you, so find a pattern you like and use different shades of gray and fill it in.

Hey Devilfox thanks for the info.

I already bought the larue ultimate upper kit.  So buying a PWS upper is not in the cards for now.  Love the look of them, though... Definitely will keep it in mind for future builds.

Now I see the superlative arms retrofit piston kit is not 300blk rated.  If I had my gas port opened up, could I make the piston kit work?  Or is that just reckless? Ha.

But I also hear they are working on a kit which will work for 300blk?  Anyone know of any timeline there/if that is true?

A little birdy told me that Adams Arms will be releasing  a 300 blackout specific piston kit in the very near future.

The first gen could be used with pistons. You just need to dremel the carrier a little. I have a 8" blackout SBR with one.