Any of you guys know the technical AND practical difference between the 6.5 Creemoor and the 6.5 Grendel? I love the Grendel because it can be used in .223/5.56 mm ARs without modification (it is simply a blown-out .223/5.56 mm case, so it uses the same bolt and magazines - you just need a different barrel and, more realistically, a different upper).
Thanks, in advance, for any comments.
Actually, no, the Grendel is not based on a 556 case at all. It has a much larger diameter case body(If I recall, based on the 220 Russian) is very short and makes up powder capacity in the diameter vice the length. The Overall length of the round is governed by how deeply you seat a long 6.5 mm bullet- some light bullets can be driven rather quickly, but any thing over 123 grain eats up capacity and thereby reduces performance, but the better drag coefficient of the long boat tail bullet makes up for some speed loss.
In the AR15 platform, the wide cartridge eats up a lot of the available barrel walls at the chamber and does the same with bolt- leaving not much metal (meat) for safety and strength.
The 6.5 Creedmoor is based n even a larger case- the 308 win/762 Nato and is much longer and greater in capacity, but is not so long in case as to require bullets to be seated deeply consuming powder capacity. It is a boutique cartridge that gets the best use of a short action bolt gun, allowing a better combination of powder capacity, bullet seating and overall length compared to chamber dimensions.
It compares a bit better in a short action to a 260 Remington, but not by much, and not if one handloads in a rifle with a specially designed chamber for the 260 ( longer throat and freebore to accommodate longer slicker heavy .264 diameter bullets). Both of these can be chambered in the Ar10 platform.
If one wants increased long range performance, the next logical step up is cartridges in the range of the 6.5/284 Win or the 6.5/30-06, or even into the wildcat range of the 6.5/7mm Win Short Mag.....
Speed costs, how fast do you want to go/how fast do you want to erode your barrel? These over bore rounds tend to eat barrels rather quickly- I know of one competitor who buys barrels in lots of five- and uses up one pre-season, two in the season and reorders at the end of the season so he has five Kriegers on hand..... ( at a cost of around $400 each...)
The trade off with the larger wildcats is recoil and blast and barrel life for speed/range.
On the other hand, a moderate load in the venerable 30/06 with a 190 BTHP at a leisurely 2650 fs will reach well past the 1k mark, and with careful development and even heftier bullets like the 210-240 grain BTHPs in faster twist barrels, will get you to 1500 yds easily...
The trade off is recoil.