Well we live in some interesting times..
I consider the 6.5 CM to be a bit of a repeat of the 22-250. Same advantages. Very accurate and better performance than the mainstay in the market. However, like the 22-250 it's harder on barrels and barrel life is noticeably shortened. Many claim this isn't an issue as the amount of rounds before the barrel is shot will be years under frequent/hard use. What I saw with the 22-250 were shooters less than impressed with having a significantly shorter barrel life. Many I know, went back to their previous favourite cartridges. Again, the 22-250 is a great, fun cartridge.
So what's different this time around? At first glance it seems to be the same trad offs of yesteryear wonder rounds. Less recoil, better ballistics than the 308. Higher velocity in a smaller bullet, but with better ballistics so you get better performance, especially for long range shooters. What's not to like about that? Barrel life is around 2500 to 3000 rounds depending on your barrel and how you shoot (long strings, or slow and lots of cool down). Versus 5000 for the 308. I've heard of 6.5 CM rifles starting to lose accuracy at 1500 rounds while others get 2500+. Again it depends. But either way the 308 gets double or more life out of the barrel. So far this is nothing new.
So far my beginning sentence seems misleading as there is nothing new here. We've seen this before. So what is interesting this time around? Well, the barrels. We are getting these round counts using conventional barrels. Barrels in the last while have come a long way. It used to be you had the option of Chrome lined or regular and Stainless steel. With Chrome lined being long use machine gun type barrels, regular being your normal accurate factory barrel and SS being for match type rifles. Well, things started to change. FN for instance has a bolt action that the FBI adopted which has a sub .5 moa Chrome lined barrel. LMT chrome lined barrels for their MWS AR308 rifles had Mike rock chrome lined barrels which many were getting sub MOA out of. However it didn't stop there.. Generally the old rules still applied. Then along came nitride treatment (Liquid Salt Bath Ferritic Nitrocarburizing Non-Cyanide Bath). This allowed the hardening of the barrel material without adding material. So now you could have the benefits of chrome lining but retain the Stainless Steel benefits. Or 4150 chrome molly steel with the benefits of chrome lining, but not the loss of accuracy and superior element/rust protection to Stainless steel. These barrel types are now available to most of us and aren't just a well known secret anymore.
I think most of us can see where I'm going with this. These new barrel processes can give the barrel life of a 6.5 CM to respectable levels. Yes, the non hard on barrel cartridges also benefit. In this case it makes a round that I would have avoided, one that I'm wanting to try out. This change in barrels is the main difference this time around.
A couple of other points I want to touch on. The accuracy.. Is the 6.5 CM inherently more accurate? It no doubt seems that way, but I don't believe it is. What I suspect we are seeing is a newer cartridge with much narrower parameters by the manufacturers. Look at it this way, the 308 has been around for ages. First 1:12 barrels were the norm for 155 etc rounds. 1:10 became popular for 150 accuracy rounds and the longer bullets. So that became more of a target shooters twist rate. Today the 1:11 , 1:11.25 is the twist rate for most military/police rifles and is ideal for the 155, 167-178 rounds. It's my personal favourite for 308 as I mostly shoot in those ranges and it works perfectly with the current off the shelf match ammo. The other two twists seem to have a lot more variation with which rounds they prefer and you generally are reloading if you want excellent accuracy. Along with twist rates there have been barrel lengths and powders... In short there are a lot of variables with the 308. Now with the 6.5 CM, you have the standard 1:8 twist rate and ammo designed for both that twist rate and the current standard barrel choices of 22-24". The ammo, barrels and twist rate are currently tailored for each other. So right now, you can go pick up some Hornady 139-143 match ammo and with a good rifle/barrel you will get exceptional accuracy. Is this a factor of the round itself or just much less variables to contend with? I believe it's predominantly the narrowing of the variables which is giving this round a lot of fanfare for accuracy. Don't get me wrong it's a good round and inherently accurate but not really anymore so than a 308. At least not until after 800 yards.
You will also see many argue that the new wonder round is looked at to be adopted by the US military. Many on here won't like what I post next. This does make sense as the bolt action in sub 300 WM calibres is completely obsolete in both military and police use today. The semi auto, predominantly an AR10/AR308 rifle has made the bolt action DM rifle obsolete. The bolt action is still relevant for 1000+ cartridges such as 300 WM, 338 LM and 50 BMG. But in 30 cal or 20 cal, the AR rules the day. Semi auto and they can shoot exceptionally well. So back to the 6.5 CM. Less recoil, better BC, and longer range accuracy. Plus it's a simple barrel swap in an AR308 rifle. Pretty much a perfect match.
My current Stag 10 build utilizes a nitride barrel but in 308. My next one will be a nitride 6.5 CM barrel. Companies such as Fulton/Criterion and now Maple Ridge armories offer these barrels for sale as fairly standard options. In my opinion this makes the 6.5 CM an exciting cartridge and one that I am wanting to try out. But... only with the accompanying technology to mitigate it's weaknesses. Which brings me to the bolt action offerings. The AR barrel systems offer easy swaps by the end user and currently a lot more options for nitride or precision chrome lining (FUlton/Criterion) than the bolt action counterparts. With the Stag 10 you can build your own. I would personally avoid buying a traditional off the shelf accuracy rifle in 6.5 CM at this time. At least until they come with nitride barrels. Or factor in changing your barrel sooner than you're probably used to.
... I’ll just leave you this quote from the owner of one of the larger independent gun stores in the USA-
