There are two basic sizes for the MSR rifles. The AR-15 is designed around the .223/5.56 cartridge. The larger AR-10 was designed around the .308 Winchester cartridges. Remington calls its version of the latter the R25. The Remington R-25 GII is available in .243 Winchester, .260 Remington, 7mm-08 Remington, and .308 Winchester, which are all popular hunting cartridges. AR-10-style guns tend to be heavy. But the new Remington R-25 GII is smaller and lighter than other guns in the class, weighing only 7 5/8 pounds, which makes it easy to carry in the woods and to pull up into a treestand. Remington accomplishes this weight reduction by using a new upper and lower receiver design, as well as a smaller, lighter bolt carrier. The GII bolt uses new geometry for the locking lugs, where every edge has a radius that ensures better reliability. There are two ejectors rather than the standard single. The extractor is almost indestructible and it mates with an elastic, polymer button that works as an extractor spring that is just about failure-proof.