I have both, just in .40, and after adding the slip on pachmayr grips, the shield fits great in my hand. The trigger on the SD really is not that great and by the time you do the Apex trigger job, your into M&P full size money. I qualified for my CC with the SD and have put about 1000 rounds thru mine without any issues. It is not a ammo picky weapon, but after leaving it alone for a year and primarily shooting my .40 shield and M&P 9c, I took it out last weekend and couldnt hit the broad side of a barn because I had gotten used to the much better triggers on the M&Ps. Just my observation though, it boils down to basically quantity over quality.

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40ShieldCT 9c SD40VE 637ct