If you got the impression that brass/ammo was expensive from me at the 'fest, that's mostly because I'm poor at the moment and have a hard time affording .22LR much less real rifle rounds. There was a reason I only had 20 rounds for my Mosin. :/
I picked the 6.8SPC as my alternate caliber AR after about 3 years of research... and, I wasn't in a real hurry. The 6.8 parent cart. is a Remington 300, which is obsolete. The 10mm Auto/.40 use the same base and rim dimensions, hence the confusion. There are several total specs: SPC, SPCII, and 6.8x43. The last two are virtually identical. The main difference is in the length of leade, with the earlier chamber dimensions not allowing higher pressure ammo like Hornady's tactical loads. Not a real reason to reject an otherwise good deal, since 15 seconds with an SPCII reamer will fix the problem. Look for something over 1/10 twist. Most like 1/11 or 1/12.
To switch any caliber AR to 6.8, you need:
new barrel
bolt (carrier, extractor, etc can stay the same)
magazine* (see below)
Pros:
legal to hunt with just about anywhere
hits like a 308 out to 200 yards
under 200y basically same ballistics (for scopes/sights) as 5.56
light recoil
prices of ammo coming down**
cons:
expensive to shoot compared to surplus 5.56
can't use standard NATO magazines without problems
... I fail to see many more problems.
*5 and 10 rounders just need a new follower. 20-round and 30-round NATO mag bodies allow the stack to skew, so you need purpose-built mags, that give you 15 and 25 rounds respectively. So if you're looking for a SHTF loadout you'll be carrying less ammo total... and kinda creepy. PMAGS I have heard the 5-round rumor, and since I was using a borrowed mag I wasn't about to test it.
Having said that, mags vary in price from ASC/ AR-Stoner at around $15:
http://www.midwayusa.com/product/776142 ... teel-black
to Barrett true 30-rounders at $40
http://www.midwayusa.com/product/163532 ... ound-matte
I've got 5 of the C-products 25 rounders (same as AR stoner) and they work flawlessly. When I remember to bring them to the range.
**Like all commercial (as opposed to surplus) rifle ammo, prices are too damn high. 6.8 has actually come down a bit since introduced; you can get Hornady 110g vmax plinking/varmint/HD ammo for about $17/20. More significant hunting or tactical ammo can be had for more; I think the most expensive I've seen is a solid copper load at about $45/20.
Personally, I reload roughly similar to the Hornady round (maybe a little hotter) and it costs about $0.47/ round including using a powder which ain't the cheapest (Benchmark) and CCI 41 milspec primers. Reloading is the way to go - and it's an easy caliber to reload, if there is such a thing. Decap and size, trim, clean, prime, charge, seat, crimp. In a progressive press I could really churn them out. As it is, my single-stage press allows me to do a couple hundred a night, start to finish.
Summary: Good hunting round for small game up to whitetail and feral hog (I know several hunters of both that use 6.8). Devastating HD round. More expensive than surplus ammo like 5.56 or 7.62 nato. Probably won't work as well with a suppressor as 300BLK. Hits but doesn't kick like .308.
IMHO - if you want a higher energy round (than 5.56) that is cheap to shoot, get an upper and mags in 7.62x39. The derivatives (6.5 Grendel and others) are more expensive, but might be right for you if you need that round's specific ballistics. 6.8 is a great intermediate round - between 5.56 and its questionable terminal ballistics (especially out of short barrels) and 7.62N with its weight and kick.
