The first time I went out with both guns, I shot at 25 yards off a bench so as to find out what these guns could do, and if they even liked the ammo I had. I used W-W plain box .45 FMJ and R-P 180 grain FMJ. The .45 did much better at the 25 yard line.
I took them up to my range a second time, wanting to compare recoil and recovery time, so didn't shoot any paper, just steel targets and plinking at golf balls.
Yesterday I went back and shot at more practical Shield ranges at some homemade silhouette targets.
The more I shoot these two, the more I like my .40 better than the .45.
Granted, my .40 is the ported PC model. If it wasn't ported, I might like the .45 more.
I have always been a .45 guy, besides 1911's, I've had a Glock 21, H&K USP, a sweet stainless S&W (645 ?) and a few others.
I'm fairly new to the .40, having only a Smith SS DAO in .40 for a while. I got rid of it as I was always sorting the brass from my 10mm, even with the slight difference in length brass was too similar.
The PC .40 has a better trigger, similar to my new .45 in weight, travel, etc. but the PC trigger is smoother, no crunchy spots like the .45 trigger has.
The fiber optic sights are easier for me to see than the 3 dot ones.
Size ? The .40 is noticeably smaller, not much but when you grab it, it feels like a small gun, whereas the .45 seems closer to a full size gun. Those of you who own both a 9mm and a .45 Shield will know what I mean.
Both have about the same muzzle rise, but the .45 comes back against the hand harder. The .45 recoil is not unpleasant, just not as pleasant as the ported .40.
The .45 does have better stippling and the safety is better, but being left handed, I can't utilize the safety quickly or easily anyway.
I shot first at 7 yards, off hand and a shot every few seconds. The .40 surprised me, 4 of the shots pretty much going through the same hole.
Then both at 15 yards:
I had one more clean target, and 7 rounds of .45 hardball left, so just for grins I shot them at 50 yards, using a stump for a rest. One round is down in the "Y" where I wrote yards so hard to see:
I know a lot of guys out there really like their .45 Shields, but my Performance center .40 has spoiled me. The porting really does help a lot, with none of the downsides some guys like to complain about.
Too much flash, velocity loss, pain to clean ? Not from my testing. If you have a chance to get a PC model in any caliber, jump on it.
Between having to have different holsters for the .45, and keep a different caliber on hand (I've been trying to streamline and simplify), I'm considering selling the .45 Shield, or at least trading it for a 9mm for my daughter to carry.
Had I not had the PC .40 first, I might like the .45 better.