The Sig Sauer P320 Nitron Full Size is a 9mm, striker-fired, 17-round, stainless steel framed beast of a handgun, with an overall length of 8 inches, 5.5 inches in height, 1.4-inch width, and an overall weight of 29.5 ounces. 

In other words, this is a no-nonsense, heavy-duty, hard-working handgun – and I’d expect nothing less from the official sidearm of the U.S. Armed Forces. 

In January of 2017, the Army announced a custom version of the P320 had won its XM17 Modular Handgun System competition, officially replacing the Beretta M9. 

Since then, it’s been adopted by nearly every branch of our Armed Forces, making the M17 and M18 the new standard military service pistols. 

This should make all of us feel a little safer, as it doesn’t get more durable, accurate, and reliable than the Sig P320. 

And while disassembly and reassembly of the P320 is slightly more complex than other 9mms we’ve explored here on Unloaded, it’s still very manageable. Simply follow the steps below. 


  1. Ensure a clear chamber. 
  2. Remove the magazine. 
  3. Lock the slide back by engaging the slide catch lever. 
  4. Flip the takedown lever to the 6 o’clock position. 
  5. Release the slide catch lever and pull the slide off the frame. 
  6. Remove the guide rod/spring from the barrel lug.
  7. Remove the barrel from the slide. 
  8. To begin removing the firing assembly, first remove the takedown lever completely. You might have to get a little aggressive with it.
  9. Use your thumb to push on the rear of the firing assembly and your other hand to lift up on the front. It should all come out as one unit. 
  10. Use spray solvent to coat the firing assembly and let it soak for a minute. Try not to get a lot of solvent in the striker channel. 
  11. Send a 9mm brush down the bore to loosen up old powder and dirt. Then send down a cleaning cloth to clean up the powder/dirt you just loosened up with the brush. 
  12. Use a cloth and some q-tips to gently wipe down the firing assembly, then proceed to wipe down the frame, slide, rod/spring, and barrel until everything comes out clean. 


  1. Put the barrel back into the slide. 
  2. Seat the guide rod/spring back into the barrel lug. Depending on the specific model of P320, the guide rod/spring might have to sit in the barrel lug a certain way. If it’s perfectly circular, it can be seated in any fashion. 
  3. To reinstall the firing assembly, first slide the trigger into the trigger guard of the frame and then guide the end of the firing assembly back into the small slots in the back of the frame. Once everything is lined up, you should be able to click the whole assembly back into place. 
  4. Reinsert the takedown lever. Check the end of the lever for the cut/flat side and line up to the corresponding cut of the frame. Slightly lubing up the end of the lever can help.
  5. Once reinserted, position the lever back into the grooves on the exterior of the slide.
  6. Turn the takedown lever to ensure the flat side is flush with the inside of the frame. 
  7. Lube the rails of the frame and slide. 
  8. Position the slide onto the rails and slowly guide it up the length of the frame. 
  9. Use the slide catch lever to lock the slide back. DO NOT SKIP THIS STEP! Don’t pull the slide back and flip the takedown lever without engaging the slide catch. The P320 requires that the slide catch lever be engaged before flipping the takedown lever, otherwise the magazine won’t fit back into the magazine well. 
  10. Flip the takedown lever back into position and drop the slide. 
  11. Reinsert the magazine and perform a function check. 

That’s it! Thanks for reading everyone! 

And thank you again to Vienna Arsenal in Vienna, Virginia for loaning us the P320 used in our Unloaded video. To shop Vienna Arsenal’s amazing inventory of firearms, or sell or trade your own firearms, please visit Follow them on Instagram at @viennaarsenalig. 

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