Best Hornady Superformance 270 Win 130 gr GMX®

Hornady Superformance 270 Win 130 gr GMX in Gas Operated Firearms

Increase your rifle’s performance up to 200 fps without extra chamber pressure, recoil, muzzle blast, temperature sensitivity, fouling, or loss of accuracy.

Superformance® uses progressive propellants that take your favorite V-MAX,® NTX,® SST,® GMX,® and InterLock,® bullets to levels of performance that are simply unattainable with conventional ammunition.

hornady superformance 270

Features of the Hornady superformance 270

It IS rocket science!®


Superformance® ammunition is loaded with Hornady® V-MAX,® NTX,® SST,® GMX,® and InterLock,® bullets for the ultimate in performance, no matter what the game.


Superformance® Propellants are the heart of Superformance® ammunition and usher in a new era of performance.


Like all Hornady® ammunition, our hornady Superformance 270  rounds use the highest quality cases and primers available. Consistent components translate to consistent shooting in the field.


  • FAST: 100 to 200 fps faster than conventional ammunition.
  • ACCURATE: Uncompromising accuracy without increased felt recoil.
  • CONSISTENT: Unfailing performance across a broad range of temperatures.
  • VERSATILE: This new breed of ammunition is available in 17 Hornet to 444 Marlin, and is safe for use in all firearm types, including semi-autos, lever guns and pump actions.

Additional Information


The Hornady superformance 270 ammunition is safely within SAAMI pressure guidelines. Gas operated firearms are perfectly safe to use with Superformance ammunition. However, we have conducted tests and conclude that some systems work far better than others.


Superformance ammunition was developed in the Hornady ballistics lab utilizing state of the art test equipment in accordance with SAAMI (Sporting Arms and Ammunition Manufacturers Institute) guidelines for pressure, velocity and accuracy utilizing test barrels with SAAMI minimum specification chambers and bore and groove dimensions.

superformance bgchart 1

All ammunition is extensively tested for pressure and velocity deviation at temperatures from – 20°F to + 140°F. All Superformance loads exhibit extremely stable performance with very little if any deviation in pressure and velocity at extreme temperatures.

The Hornady superformance 270 propellants provide a longer duration/application of peak pressure in the pressure time curve that occurs within the barrel (see Fig. 1 pressure curve).

In other words, both Superformance and standard propellants provide an equally powerful “push” applied to the base of the bullet, but with Superformance propellants, the “push” is applied for a longer period of time.

Once the peak pressure dissipates, the Superformance powder burn returns to a “normal” curve, similar to standard propellants. This illustrates the highly progressive burning characteristics of the powder and its ability to completely burn. A complete burn of the entire Superformance charge takes place in a shorter period of time, creating far less velocity reduction in shorter barrel lengths (barrel length = time to burn).


The hornady superformance ammunition is tested and is safely within SAAMI pressure guidelines. Gas operated (direct impingement or gas piston) firearms are perfectly safe to use with Superformance ammunition. However, Hornady ballisticians have conducted testing with a variety of guns (including guns equipped with suppressors), and our findings conclude that some systems work far better with Superformance ammunition than others.

It is recommended that to get the best functioning with Superformance ammunition in gas operated/gas piston semi-automatic or select fire guns, rifle length gas systems with 20 inch or longer barrel lengths are best for reliable firing and extraction.

Any other configuration, particularly shorter barrels/gas systems are best served with the installation of an adjustable gas system, ESPECIALLY if a suppressor is to be installed.

Due to the longer duration of peak pressure produced by Superformance™, the post peak/declining port pressure at common carbine and mid-length gas port locations is still higher than that produced by standard propellant.

This has a tendency to flood the system with a larger volume of gas, at a higher velocity, that tries to open the bolt of the gun too fast. It’s a timing issue. The cartridge case is still swollen from the application of pressure during firing while the gun is simultaneously trying to extract the cartridge case before it has had an opportunity to settle back to its original size, or more simply: the gun is still in the process or firing while it’s trying to extract the cartridge case.

If the firearm and the ammunition are not in sync, there can be what is commonly identified as “pressure signs” on the cartridge case. This is exhibited by the movement/marring of the head of the cartridge case, cratered primers, flat primers, ripped or ruptured cartridge cases, “popped primers”, and/or any combination of these effects. If any of these “pressure signs” are apparent, stop firing immediately.

If an adjustable gas system is installed, it is advisable to reduce the amount of gas flowing through the system by closing the gas port until the gun operates correctly.

With the installation of an adjustable gas system, gas pressure can be metered to a point that enough gas is applied to open the bolt, but at a slower rate to allow the cartridge case to return to its original diameter prior to the movement of the bolt, and thus allow for proper extraction.

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