Open Guns. 9mm or 38 Supercomp?

pros and cons of 38 supercomp vs 9mm major when building a open gun for competition.

I’ve been asked what caliber Open gun would be best for USPSA/IPSC competition a lot this past month. It’s something I’ve had to research a great deal lately because of the Open build Mclearn Custom did for me last month. Caliber is the number one question when building a major open gun and deserves careful consideration.

The two main options nowadays are either 9mm major or 38 supercomp. Both have pros and cons and both are good options. I want back and forth for a long time deciding


                                                                     PROS & CONS


  • 38 Supercomp Pros:
  1. Softer shooting
  2. 10 plus reloads per case
  3. More consistent ejection
  4. Many powder options
  5. Able to use standard upright C-more with large viewing area.
  • 38 Supercomp Cons:
  1. Expensive initial investment “Starline Brass”
  2. Losing brass at major matches that are lost brass matches
  3. Having to pickup brass all the time

  • 9mm Major Pros:
  1. Little to no initial investment
  2. Don’t worry about retrieving all your brass
  3. Major matches don’t cost any extra because of lost brass
  • 9mm Major Cons:
  1. Erratic ejection because of mixed headstamps
  2. Unreliable with upright mounted C-mores “because of #1”
  3. Snappy compared to Supercomp
  4. limited powder choices when making major
  5. short brass life “2-3 reloads max”
  6. Need to use micro dot sight or side mounted C-more


I originally wanted to run 9mm and not change my reloading setup or worry about picking up brass like a crazy person. It was a struggle, on the one hand 9mm brass is cheap and easy but I really wanted to run a standard C-more mounted upright, any chance of a malfunction is not an option at nationals level matches. I had to take a deep look at what my goal for the pistol would be. Winning was that goal and after going round and round I finally decided that the extra initial cost of 38 Supercomp would put me in a better position to perform at my best.


Here’s a picture of the completed open gun by Mclearn Custom



7 thoughts on “Open Guns. 9mm or 38 Supercomp?”

  1. 9mm is just as good as 38SC. 5 reloads out of the brass. Same powder used for 38 Hodgdon HS-6. Tune ejector for upright mount. Use a more modern comp design and 115 grain bullets.


  2. I reload 9mm brass to major until I lose it. If erratic ejection is due to inconsistent head stamps then buying new Starline for your 9mm is an option just as it is for supercomp. As a bonus, buying cheap same head stamp range brass is an option for 9mm too. I do this for major matches but gun still runs 100% on mixed in practice and at locals. Popular powders in supercomp like 3N38, 3N37, AA7, and HS-6 also work excellent in 9 major. Pretty much N105 is the only powder option you lose going to 9. The recoil impulse and being able to run N105 are the real benefits of 38 supercomp. The increased amount of ammo for the price is the benefit of 9 major. Both can easily be set-up to run 100% and both gag when improperly maintained or fed with shoddy ammo.


  3. Once fired 9mm cases are still relatively expensive where I am at about USD $70 per 1,000 so I just reuse them until they split or won’t fit in the case gauge.

    I find maybe 5-10 in a 1,000 split and even if the odd split case gets reloaded they still seem to work fine.

    It’s pretty easy to tell when a case has split though – at the end of the stage when you have collected your brass just give the hand full of cases a shake and if there is a split case in there it sounds very distinctive. Then you just search through the cases until you find the split one.

    I shoot a CZ and cannot ever recall having a problem with case ejection due to the upright C-More.

    I have only had 1 partial case head separation and it still ejected fine.

    I have yet to find a loose primer pocket.

    After about 35,000 rounds (minor and major PF) I had 2 cases fail to eject and I dropped in a new ejector and ejector spring, problem fixed.

    I cannot claim the CZ has run without fault and there will be plenty of people who will have shot more rounds than I have that have had a different experience, however the biggest problem for me is not the reliability but keeping enough powder in the case when reloading to make major.


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