Since there are shield turrets, can we get a large (or even small) port shield blaster gun?

No. Well not until the shield turret works like it is supposed to. You can actually kill people with it. A better shield gun would just be a stationary plate like the ones you fire that just blocks (some) incoming fire in the direction you point.

As it is, it not only does not work like a shield but also makes a better offensive weapon than a defense mechanism. I'd suggest that gets fixed first.

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