Which is better for running suppressed (tri lug rugged obsidian or odessa 9)with a red dot and why? I think its past time for me to get a mp5k clone.

Leaning towards ptr because it looks ready for a red dot and light on those rails

I personally own a ptr 9kt and I absolutely love it. However one big thing is that in order to shoot the k model with a can you need to change the locking peice to an #28 80 degree locking piece and then check your bolt gap (I used cheap feeler gauges from harbor freight to do so) this aids in the keeping the gun locked longer from the added back pressure.

As for a suppressor, if you already own one, any well built 9mm suppressor will sound great on it. If you are looking at getting a dedicated can for the mp5, I'd recommend either the rex silentium mg7 358 or the dead air wolfman, both sound great out of mine. If you are planning on using  the can across some pistols, my buddies use the obsidian 9 and absolutely love it.

Tri lug on my new ptr is out of spec and unable to get a response from the factory.  

Tri lug on my MKE works perfect and cones with metal mags —also comes with a rail mount

Go MKE

Great prices on mke guns from atlantic w a $200 rebate.

This.

Its a no brainer.  The MKE guns are simply phenomenal values at current pricing plus rebate.

I went with MKE. Unfortunately before the rebate. The rail on the PTR is the reason I didnt go with it. My AP5P runs fine suppressed with stock locking piece.

Just ordered an AP5 from Dehlonega Armory.  Price is cheaper than Atlantic.  Placed the order on Sunday got notification that is shipping today.  $200 rebate is from Century so you get that too.

I've got several PTRs and a MKE from several months back.  The MKE (ap5) gets the nod.  They ship with a clamp on rail which makes the PTR's welded on rail a moot point.  Plus the MKE ships with metal mags while the PTR has the doodoo plastic ones.  A while back, I got metal PTR mags and they're just rebranded KCI ones.  Century advertises the MKE guns as having a CHF barrel.  The PTR I believe is button rifled.  My PTRs have different style trigger groups.  One of them has one that looks like everything is machined instead of stamped, and it sucks.  The trigger in that FCG does not like to reset sometimes.

PTR does ship with a significantly better hard case and a metal rail with mlok.  I dont really use the case, and I SBR'd my gun and running a mp5k front VFG.  So both of these ended up being useless to me.
MKE ships with a garbage plastic case and a flash hider.  The case is useless and honestly, the flash hider is not all that useful either.  I always shoot suppressed.  They could have kept those and knocked the price down even more.

And icing on the case, these were both $1600 before and the MKE had the edge.  Now the MKE is $200 cheaper.  No brainer.

I just ordered an AP-5 from Atlantic and Olán on getting the 80 degree locking piece. What should the bolt gap be?

@Tdwp1122

Between .010 and. 020. I like to set mine between .016 and .018.  It will decrease as the gun wears in. A set of plus 2 rollers will increase bolt gap by approx .004.  A set of plus 4 by approx .008

PTR comes with a warranty, which is good because you're going to need it

I guess I’m going to find out. I have a 9KT that I’ve had for a couple years. It has been flawless with all ammo. The rail was canted so looking through any optic had the right side of the front sight in the center of my sight picture. I cut off the rail.
I just walked into my LGS and there was an AP5-P in the case someone sold because they needed the money. Brand new never fired, and $150 under current price with rebate.
I pick up the AP5-P on Wednesday and should get to the range next weekend to compare the two side by side.