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Out of those three rifles, I would choose the UTG L96 out of them, WELLs have even worse parts than most clones.

 

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Spartan is also right, the BAR 10 would be a good choice as well, if you're looking for something better than all three of the above.

 

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If you're wanting to upgrade the BAR 10, simply get the Zero Trigger unit, and spring guide, and a spring. You'll be set for a long time, assuming that the cylinder has the same tolerances as it's TM counterpart.