A properly setup up 2011 gun should not need any particular maintainence costs. You can throat a barrel in an Open gun in about 100,000 rounds, though. A new match barrel will then cost about $350-$400 to fit. If you run a shok buff or STI recoil master guide rod you really don't have to change springs until the gun will no longer feed. That's somewhere over 10,000 in my Limited gun.
Most people go to Open in order to use optics and compensators. The shorter guns (stinger) are faster to transition to target to target, but have a more violent muzzle blast. They need more powder to make Major power factor and to run the compensator than the 5" weapons.
Open class can be pricey to feed as the rounds often take 8-10gr of powder and the brass is expensive when compared to .40 and Limited.
Your only options are not just STI guns.
You have SVI, Brazo Custom, Dawson Precision and Triangle Shooting to all turn out killer custom/semi custom guns.
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