The AR-15 is the belle of the proverbial rifle ball and has been since its original manufacturer ArmaLite sold the rights to Colt for mass production.

But it has an older brother: the AR-10.

The AR-15's proliferation wouldn’t be if not for the development of the AR-10—the rifle’s slightly larger predecessor. The AR-10 was first brought to market in 1956 as a paratrooper rifle, according to a history of the firearm written by Army Reserve Maj. Sam Pikula.

Labeled as a lightweight gas-operated assault rifle, it boasted a “direct gas impingement,” which gave the AR-10 the power to fire off 700 rounds in 60 seconds with a muzzle velocity of 2,772 feet per second, explains an essay on Daily Shooting.

The AR-10 never achieved the following of its successor. It wasn’t mass-produced, and it is scarcely mentioned. But that doesn’t make it any less of a quality firearm.

The side-by-side comparisons of modern AR-10s and AR-15s show some stark contrasts for those who know semi-automatic rifles well, but for those of you looking to tip the scales in favor of one or the other when buying, look no further than Savage Arms, which gives to both enthusiasts and experts alike its MSR-10—an inimitable offering.

What sets apart the MSR-10 from a traditional AR-10?

One of the stumbling blocks to creativity and innovation with the AR-15 as a platform is the nagging need for conformity, enforced by the rifle’s need to stay compatible with its wide variety of accessories. With AR-10s, there are far fewer such constraints.

Savage’s MSR-10 designers shaved off the rifle’s unnecessary weight and trimming size with a smaller, lighter chassis that strikes a perfect balance between performance, fit and function. Its two variations, the Hunter and Long Range, are available in .308 Winchester and 6.5 Creedmoor chamberings, which have applications in both hunting and long-range shooting.

So why did ArmaLite develop the AR-15 in the 1960s?

In short, timing may be to blame. The ArmaLite AR-10, designed by Eugene Stoner and revolutionary at the time, was produced on the heels of the T-44, which would find greater favor with American soldiers and eventually become the M-14. In an effort to compete, ArmaLite developed a smaller, lighter upgrade of the AR-10 at the Army’s request: the AR-15.

In total, fewer than 10,000 original AR-10s were produced, but despite cutting production in 1961, the rifle’s contribution to the future development of small arms cannot be understated. It was revolutionary in its use of the direct impingement gas system, lightweight materials, an in-line layout, and of course, the multi-lug bolt. Ultimately, these advancements would lay the groundwork for the cult-like following of the AR-15, which would be named the M-16 when the Air Force first purchased the rifle in 1963.

And Savage’s MSR-15 certainly is not lacking, not by a long shot. Its take on everyone’s favorite firearm features the proven 223 Wylde target chambering that boosts versatility without sacrificing downrange performance. It boasts accuracy from both 223 Remington and 5.56x45mm NATO ammunition. Called the “Recon,” Savage’s AR-15 variant features an AR Blaze trigger system that meets mil-spec definitions and dimensions but has been given secondary polishing and hardening to enhance trigger pull.

Both of these Savage MSRs feature a twist on rifling that boosts accuracy and reduces barrel fouling. As most shooters know, rifling improves accuracy by spinning the bullet as it travels down the barrel. Savage R5 Rifling gives gyroscopic rotation that stabilizes the ammunition in flight. The rifles also boast barrels that can withstand harsh conditions through their extremely durable surface hardening treatment known as Melonite QPQ. Short for “quench, polish, quench” the finish is harder than chrome and provides corrosion resistance far superior to standard market coatings and platings.

So which one should you choose? That’s up to you. While each may boast advantages in certain circumstances, they’re both incredibly powerful rifles that take 50 years of history and pair it with modern technology to do whatever job you need done.