DTI AR-15 rifles are chambered in 5.56X45 NATO, so both 5.56 and .223 Remington ammunition is safe to use in them. 5.56 ammunition typically has more velocity and higher chamber pressures than .223 ammunition. This potentially higher chamber pressure and size differences in the leade (throat) of the two weapons are reasons it is dangerous to use 5.56 ammunition in a weapon chambered only for .223 Remington. The selection of 5.56 ammo is a bit more limited, though recent military activities and developments have increased available options. Not long ago, almost all 5.56 ammunition was loaded with "ball" ammunition/FMJ (full metal jacket). There are now a few different manufacturers that produce 5.56 ammo with "open tip match" or expanding bullets.
Ammunition in .223 is also fine to use in your AR-15 and the available ammunition options are much greater in this caliber. From FMJ to expanding solids to various hollow point designs, a perfect option for just about any shooting application can be found.
Both 5.56 and .223 ammunition is available in a variety of bullet weights (grains). Typically, the lighter grain bullets are more suited for varmint hunting and target shooting/plinking, while a heavier grain bullet will perform better in situations like deer hunting or self defense. There is a line of thought that the lighter weight bullets are more accurate with slower twist rate barrels (1X9), while heavier bullets perform better in a faster twist rate (1X7). DTI rifles with 1x9 twist barrels that were featured in recent publications/tests achieved sub MOA accuracy with bullets as heavy as 77 grains. Each individual weapon is different and can show a propensity to favor one type/load/weight of ammo over another in terms of accuracy as well as reliable functioning so it can be beneficial to try some different brands and types of ammunition to see what offers the best performance in your weapon.
It is always our suggestion to use quality American made ammunition. Some brands produced elsewhere may be manufactured with lower quality components such as powder that does not burn consistently (creating lower pressures) and can affect the reliable functioning of a semi automatic weapon. Not all ammunition produced in other countries is bad, but it is wise to research user reviews and other information before purchase/use. In this economy it can be tempting to select a cheap brand of ammo, but do so with caution. Whatever you do, don't buy it in large quantities until you're sure of its performance.
Treat your weapon well. Feed your valued gun ammo that will allow you to enjoy the shooting sports without concern. Clean your weapon after use, and always remember to practice safe weapon handling.
Thanks for reading our blog. If you have any questions about the DTI rifles and the other AR related products we sell, or even about the AR-15 in general, please contact us.