I'm looking for a 900 yard and in gun in a semi auto.  I want it in 6.5CM just to keep ammo simple for when I get into reloading.  I've decided on the Aero M5E1 as the gun I'll start out with and this will be suppressed basically 100% of the time.  I may or may not drag this thing through the forests and mountains here in VA.

Will an 18" barrel drop my velocity too much for the ranges I'm looking at?  I want it as short as possible especially since the suppressor will just add length.

Link for those interested.  On mobile so I can't hotlink

http://www.avantlink.com/click.php?tt=cl&pw=55963&ctc=j3nedb9ml600zk8a02gtd&mi=13601&url=https%3A%2F%2Faeroprecisionusa.com%2Fm5e1-complete-rifle-18in-6pt5-creedmoor-ss-mid.html

I think an 18" would be just fine if your not expecting to much. The grendel will ping steel at 800. Plus with the suppressed option you're not getting unwieldy.

No I have a bolt gun that'll reach our further if I need it plus another bolt gun I'll be ordering soon.

Falkor Draco's barrel would be my first choice, no 18in though.  Or have CLE spin you one.