I like the DD MK18 but I am not married to it.

I am told that gas port size and barrel length in this range when you are suppressing is tricky.

What are my options for a good upper complete that wont give me problems suppressed?

You set on the 10.3ish range? BCM and KAC both make complete 11.5s

Yes, I want to keep it at 10.3 or 10.5.

I cut down a BCM 11.5 to 10.5 and it's been worry free. Also have a 10.5 PSA budget upper with their premium BCG, it has only had one failure and that was running it full auto, suppressed, with steel-cased ammo. Both have a couple thousand rounds through them.

Also have a 10.5 Ballistic Advantage-barreled upper that has been great

I think Andro uses BA barrels.

I have a 10.3 or 10.5 upper with a BA barrel that I shoot suppressed ~90% of the and I've only had one malf that stopped the gun, and I attributed that to the ammo (steel case, FTExtract).

Current production DD Mk18/DD 10.3" barrels are running what many consider the optimum port size for that barrel length (.070"). That's pretty much the sweet spot for a gun that will be used suppressed and unsuppressed. If you're shooting it 100% suppressed, certainly you can go smaller, but as you go below .070" you're going to start limiting your unsuppressed reliability (and eventually eliminate unsuppressed function altogether if you go small enough). Older DD Mk18 uppers (prior to around spring 2017) ran a much larger .082+/- port, and I wouldn't recommend those without modifications to address the oversized port.

Building would give you wider options, but there are a few uppers with .070" ported barrels: the DD Mk18, Andro Corp "Crane Spec" 10.3" and LMT 10.5" come to mind. The Geissele URGI 10.3" will likely run a DD 10.3" .070 barrel as well - if it ever comes out.

darn good feedback on my question there above.

thank you

sounds like the DDMK18 is the way to go if I dont mind spending $1100 for an upper

Brownells sales and active junky. Save $$

I built my DD Mk18 Mod 1 over time, but used relevant DD parts. This was back when they had the larger gas ports. I love mine, it is probably a bit overgassed, but I don’t notice it too much and I assume my Sandman helps a bit compared to other suppressor designs. My DD 10.3” barrel is considerably more accurate than it has any business being. I would get one again, especially with the smaller port.

Yeah, if you buy from Brownells as mentioned, you can get the stripped Mk18 URG for $600-$700 (depending on the sale price plus coupons/AJ discount). Add a Toolcraft BCG for $70 or a Colt for $125 and a charging handle - you have a complete upper for around $750 or so.

The latest production is PERFECT for suppressed use.

Now, the one I own is not "tricky" it is flat overgassed!  I am sure that is what you have heard.  I run mine with a can, but with a lot of spring and buffer behind it.

Buy a new MK18 upper with confidence.

My recent DD 10.3’s have run great suppressed and are very accurate. Good barrels.