The data I am considering for a 16” is below.
The gas blowback between a 16 inch and 18 inch, both utilizing a intermediate gas system barrel are going to be very minimal diference from each other, but the problem that a lot of people are overlooking is that with that caliber the pressure curve is insane, and in that pressure range you're almost going to immediately erode your Gasport.
And once that damage is done to your Barrel you're going to get inconsistent Flyers and deterioration in accuracy.
Moreover the point I was trying to press on you is that people think you can take the data from a 16" bolt gun and compare it to an AR. Doesn't work that way at all!! you cannot control the pressures in an AR like you can in a bolt rifle. You are going to be significantly under your stated or ideal muzzle velocity, and if you do try to push it you're just going to put yourself in a world of hurt blowing primers, piercing primers, and just completely warping primer pockets in your brass.
There is a very valid reason why nobody has "SUCCESSFULLY done this. You will also see people making false claims of getting 2800 to high 2700's fps, and it's complete Bullshit.
If you want a shorter 6.5 Creedmoor that's fine, but don't go any shorter than 20" with a rifle length gas system.
And if you really need a shorty then go with .308
You have a world of options with a short-barreled .308 you can run the 155 palamas they have a high BC and higher MV. You also have endless supplies of store-bought ammo on the cheap.
The only way that I can safely recommend anybody to do a shorty 6.5 Creedmoor is if you made it a dedicated suppressed platform, and the reason why is, the suppressor acts as a rough extension of a barrel and usually provides a bit more muzzle velocity but then you're dealing with a whole nother animal with the nasty blowback and just a very dirty running machine so if you can get a gas piston system that would be the way to go with a suppressor.
