tl;dr
What is everyone using to suppress the 6.5C in what barrel length?
Long version:
So I’m in the very beginning stages of a 6.5 Creedmoor build/long term project and I’m looking for advice on a barrel and suppressor combination. This will be a semi-auto gas gun; built, not bought. I’ve come to the conclusion that I prefer suppressed shooting and basically just plan on buying a suppressor when I start a new project; i.e. every gun gets a can. This one will be no different.
Haven’t done any precision shooting, have ranges nearby out to 500 yards and potentially 1000 yards+ by the time this build is done. I’ve already got 5.56 and .308 builds in the works for shorter distances, with cans picked for those. Just building things as the sales come along, no rush. The barrels on these will be 18" or less, so a suppressor wont make the overall length “too long.” It seems as though a lot of people are happy with the 22"+ barrels in 6.5, and with a suppressor were talking ~30" length by the time its together. I generally prefer things on the shorter side and I’m having trouble wrapping my head around a combination that long.
I know they make 18" barrels for the 6.5, but ive read that the longer barrels and gas systems are smoother shooting and easier on brass due to lower port pressures. I also realize that there is no free lunch here. Just looking for some experience from the knowledge base here.
They’re using lighter projectiles (123gr instead of 140) and faster burning powder (Varget instead of h4350, RL16, etc) and seem to think it is a good compromise that makes the rifle more practical than a 26" match gun with another 8" of suppressor on the end of the barrel. There is a penalty is terms of velocity of course.
This article on rifleshooter.com does a decent job of comparing a short 6.5CM to both a 26" 6.5CM and a 22" 308. The short Creedmoor gives up a lot to the 26", but it does seem to compare favorably to the 22" 308 (shooting 175 SMKs) while being a much handier rifle, especially if both are wearing cans.
All bolt action rifles, but it is a place to start.
ETA: Even with all of the above in mind, if you’re just going to shoot the gun prone or off of a bench and don’t plan to hike or hunt with it, you’ll probably be happier with a longer (20" to 26") barrel.
You’d be about 200 fps faster than a 16" Grendel (most guys seem to be getting around 2400-2425), assuming both guns are shooting 123s. For comparison, by going from 26" to 16" with the CM you’re giving up about 175 fps. So the shorter CM sits in between a 6.5 CM match gun and a 16" Grendel.
The Creedmoor would also still allow the use of heavier projectiles (up to 147s), something you can’t really do with a Grendel.
Still, it is cheaper to build an ar15 than an ar10. And the Grendel is a great cartridge.
I was pointing out that a 16" Creedmoor will give you basically the same trajectory as a 22" 308 but in a lighter and more compact package (that would be handier with a suppressor attached). The shorter, stiffer barrel might also help with POI shift with the suppressor attached vs un-attached. So there are some advantages to the short 6.5 in that respect even if it isn’t a 26" match gun.
The short 6.5 should also still slightly out perform the 308 out past 600 yards in drop and wind drift, although not to the same extent as a a longer barreled Creedmoor. And you still get the lighter recoil impulse of a 6.5. That’s also assuming you’re shooting heavy 175s in the 308, not something lighter/with a lower BC (147s, 168s, etc.) where the advantage would be even more in favor of the Creedmoor.
