I bought my P-345 for a couple good reasons. My favorite carry and combat shooting gun is my Colt Commander. I really like the size and I can shoot it very well. I've been wanting a Picatinny rail and a lighter weight for a carry gun. Don't want to booger up the Colt by modifying it so I looked at the Ruger KP-345PR. It weighs 29 oz empty whereas the Colt is 42 oz.
Being a gunsmith, the first thing I did was tear it down to see what changes Ruger made from the older P-guns. I found some interesting things, mostly positive but a few that were a bit negative. The magazine disconnect, loaded chamber indicator, and key lock are viewed by many as a negative. I don't have a problem with them. The DA and SA trigger pull are way better than previous P-guns.
I really like Ruger's new cam-block barrel locking system and their recoil buffer spring really works. The lighter Ruger has less felt recoil than the heavier Colt. Accuracy isn't quite as good as the Colt but well within acceptable limits. I'm getting 2" @ 25 yds (from a bench rest) average groups with a variety of ammo. So far, not a single malfunction in about 500 rounds. I've shot LRNs, JHPs, SWCs, and FMJs without a hitch.
I really am not a DA/SA auto fan and prefer the full time SA feature of a 1911. I carry my Colt cocked, locked, and loaded. The Ruger is plenty safe to carry loaded but not cocked. In fact when you put the safety on, the hammer drops (decocker). So the Ruger has to be fired DA the first shot, then SA until you stop. This will require some practice for first shot accuracy.
When operating the P-345, I found one annoying thing. With the safety on, you can squeeze the trigger until the hammer goes about half way back. If you force the trigger further, a little lip on the firing pin interrupt system will bend or break. The older P-guns totally disconnected the trigger with the safety on. This is very minor because I will carry the gun loaded with the safety off. That requires about the same trigger movement and pressure as a standard DA revolver.
Another issue was the way they made the magazine disconnector. The lip of the magazine presses on a firing pin interrupt plunger. Without the magazine in place, the gun appears to function normally with exception of the firing pin being interrupted and won't fire. After a few dry fires without the magazine in place, I noticed the firing pin was dragging. I took the slide apart and found the firing pin had peened the interrupt plunger. I used a file and dressed the plunger back to normal. My conclusion: it is OK to dryfire the gun but the magazine must be in place.
The sights are great and make a nice holster profile, better than my Colt. The grips are cast into the polymer frame so they can't be changed. They fit me fine but others might not like them.
Guns & Ammo did a nice feature article on the P-345 (October 2004 issue). It doesn't mention the things I found but does have a lot of good information. Keep in mind; I paid $325 OTD for the Ruger and could buy at least two for the price of another Colt. It's not the best gun I've ever owned but for the price, it makes for a very reliable carry gun with good features.