Small Frame AR10 vs. Full Size AR10: What’s the difference?
Is the Small Frame AR10 just a condensed version of the full size AR10. That’s the question I get quite often and then answer is no, and here’s why. The Small Frame AR10 shares more characteristics with an AR15, and not because it’s identical in size from the magwell back, but more to the fact that it runs and feeds flawlessly across every AR10 caliber. The traditional AR10 has at times struggled with certain cartridges outside of .308 and bullets with a shorter overall length (OAL). There are manufacturers that have gotten some of these calibers to reliably run, but I think that has more to do with the skill and competence of that manufacturer, rather than the DPMS Gen 1 pattern design.
So what makes the Small Frame AR10 more reliable in feeding and function across every caliber you throw at it. Simple; the geometry is improved in subtle but significant ways, particularly the bore axis, which is lower on the Small Frame AR10, and that makes a substantial difference in feeding reliably. Why is that important? It has to do with the travel as the bolt returns and strips off a new round. In layman terms, the cartridge has an easier path into the chamber. The higher bore axis on the standard AR10 means the round has to travel at a steeper angle before entering the chamber. The lower bore axis on the Small Frame AR10 lends itself to creating a more linear path for the bullet to travel as it’s stripped off the magazine. It does not need to travel as high, before it redirects into the chamber. Furthermore, damage to the projectile tip is less likely because the travel is smoother. When discussing true precision shooting and getting everything you can out of a rifle and cartridge, minimizing the damage done to the tip of your projectile certainly warrants a discussion. Hollow point and ballistic/polymer tipped projectiles are very common with high-end quality match grade ammunition. Unfortunately, these projectiles are susceptible to damage during feeding. The more linear and streamlined travel of that projectile in the Small Frame AR10, because of the lower bore axis, results in less damage and more uniformity between shots.
Another example, is the .22 Creedmoor or similar cartridges that don’t quite reach mag capacity. We have done a significant amount of testing with the .22 Creedmoor and its shorter OAL of 2.64” (75 grain ELD-M) means more travel from magazine to chamber, versus a .308 Win for example. To put this in perspective, feeding issues are non-existent in the Small Frame AR10.
Now back to the original question, is the Small Frame AR10 just a condensed version of the full size AR10? Clearly it is not, but let’s say the only difference is in size. If that was the case, it still offers significant advantages in size and weight, which do matter quite a bit outside of Bench Rest shooters. To cite an example; we weighed our SF-10 .308 with a NightForce ATACR 1-8, NF mount, Rugged Suppressor (Micro 30), and ATLAS PSR Bi-Pod. It came in at a few ounces over 10lbs. That entire setup, just 10lbs.
Next blog post we’ll start deep diving into the .22 Creedmoor and why it’s hell on coyotes and deadly accurate, like sub 1/2 MOA accurate.
Thanks for reading!