So I've seen a few threads pop up about this, so thought I would suggest a reason, potential solution.
I'm assuming the overshield effect is actually a 'shell model' of the gun with a fancy shader applied. This means the effect is actually duplicating the weapon model when used ( correct me if I'm wrong ) AND adding a potentially expensive shader on it. The newer weapons added to the game are much, much higher detail model wise, so this effect is going to be considerably more costly on them.
My suggestion is, do we actually need the effect on the weapons models at all? Technology lore wise, wouldn't the shield just envelop the wearer itself and not what they are holding? The effect would still be visible on the arms and a cheap, subtle screen edge effect could be put in place so it's still noticeable when aiming. This would also remove the need for gradient blending of out the effect on ADS and any other associated costs.
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