APA Little Tuna

Thread Diameter


  • Increase Accuracy 
  • Tune Factory Loads






The APA Little Tuna is a product of a partnership between APA and Adaptive Tuning Systems (ATS). This tuning device attaches directly to the APA Little Bastard. Simply replace your existing jam nut with the Tuna nut and you’re ready to start finding the node your ammo wants. Whether your barrel is speeding up post break-in or temperature swings have influenced your load at a match. Or maybe you really just want to shoot a specific factory ammo that your gun doesn’t love; the Little Tuna is your guy.

 How To:

Start by removing the jam nut on your APA Gen 3 Little Bastard Muzzle Brake. Install the Tuna nut onto the brake just like the original nut. Now re-install the brake onto the barrel as before. Slide the Little Tuna weight over the front end of the brake until the threads engage and thread the weight all the way down until it bottoms out. Tighten the set screw down (not much pressure is needed here). Begin testing by shooting a 3-5 shot group. You may see an immediate change in POI and accuracy. If the accuracy does not improve right away it's time to start adjusting the weight by rotating counterclockwise. We recommend two notches or 90 degrees of rev per group in the beginning stages of testing and smaller increments for fine-tuning. We also recommend not going past 1080 degrees or 3 full revolutions. If 3 full rotation is exceeded, the Little Tuna system may require more frequent cleaning.

 We recommend cleaning the Little Tuna system every 200 rounds or between matches. The Little Tuna only functions on APA muzzle brakes. The Little Tuna is 1.7” long and 1.49” in diameter. Can accept barrel contours up to 1".

 The adjustable weight is 5.6oz and uses a 3/32 Allen key wrench.