My wife has no pistols larger than 9mm, but when we venture into the woods, I would like her to pack something with a little more oomph.

Underwood ammo builds a 200 grain .40 load that looks good on paper, similar to say a 44 special. I am thinking it would penetrate a cougar fairly well. I have an old G23 that collects dust. Thinking this would be a better option that a .357 Sig. What says the hive?

Load in question is here 200 grains of fury

Other then that, my M&P45 would maybe be an option.

I'm a big fan of the .40, but in your wife's case if she's used to shooting/carrying a 9mm then she should just stick with what she knows. The odds of her needing to shoot a cougar are so remotely small that it's almost irrelevent, and it's better for her to use something she's comfortable/confident with.

A 9mm she can make a hit with is far better than a .40 she'll miss with.

Even with women I know that could shoot pretty well with a 9mm, they almost always have a tough time with .40.   Its snappy and torquey, making it really hard to keep the flinch from creeping back.

If you MUST get her a .40, the softest recoiling .40 I've shot is the M&P.  Not trying to start a M&P vs Glock war, but back in my academy days, I had more than one female recruit come in with a Glock 22 or 23 who couldn't qual with it.  The minute they grabbed an M&P 40, they lost their flinch and got back in it....and all made the switch.  The M&P 40 recoils like a 9mm, so its very easy to shoot.  Not sure how or why, but it handles that round very well.

Give it a look.

Let me start by saying a G23 was my CCW and go to for many years, I am very accurate with it, but would vote no. My wife is an incredible shot and after one round through the 23 handed it back to me and said "hell no" Way too snappy. If your wife is good with the recoil and comfortable the way the gun handles then go for it, but that particular gun does recoil a bit.

I'll have her try my G23, if she can't shoot it well, her G19 with 147s will do just fine.

ETA, I have to be honest, it's prob been 2 years since I have shot my G23, so I don't really remember how much recoil it had.

That statement alone is a problem as long as you are in the handgun caliber range you will still be limited to handgun power.  Handgun's in service calibers do not have more "oomph" if you want oomph you would need to look to big bore revolvers or consider carrying a rifle.  9vs40vs45 will be little difference ballistics have shown and proved this it comes down to quality of ammo and is it designed for the purpose you use it for.

Yes indeed.

9mm is plenty for cougar type beasts
we use to drop them out of trees  with 22 mag .

If you want to be over gunned 9mm is very good, 40 and 45 are great if they are wanted
But
10mm is king IMO

10mm while it has benefits does not offer a improvement over service calibers because it still is a handgun cartridge.  If you are looking for bear dangerous game stopper service caliber handgun rounds are not going to cut it period end of story.  What will win is magazine capacity and shot placement with whatever caliber you choose.   .380 and mouse calibers are completely out of the question as they have penetration issues all together.

WHAT THE FREAK DOES, "IN THE WOODS" MEAN?!?!?!

Seriously, are you talking about hiking, backpacking, strolling around a bit, or just driving out there?  How can anyone give you a reasonable suggestion without knowing that?  

Holy fuck, I guess I need to use more smileys.

There was some sarcasm in the statements in red. I was primarily looking for a deeper penetrating handgun round, and yes, 10mm does a better job of penetrating...

When I says woods, I mean day hikes and hunting. Have been quite a bit of cougar and bear activity on my uncle's ranch where we spend a good but of time, but 124 GDHP +Ps don't inspire me with confidence on a critter that is pure muscle and bone.

Like I said in an earlier post, I'll be looking to switch her out to some 147 grain HSTs

Shooting a tree'd coug is a little different that shooting one that has been stalking you for 500 yards.

Big bore revolvers are out, A more real threat is the occasional trespassing pot farmer trying to scope out a patch. I've ran more than a few trespassers off.

As far as bears, we aren't talking grizzlies here, just a measly 300 lb black bear.

There's a standard pressure cartridge designed by Buffalo Bore for the .40S&W that would be perfect.  It's a low flash cartridge called the .40S&W Outdoorsman designed to penetrate deeply for critters that want to eat your face.  Personally, I'd go with a M&P40 because it makes .40's seem like no big deal.  I have one and it is a really low recoil gun compared to other .40's on the market plus you can swap the barrel and mag and have a 9mm or a .357 Sig for that matter.

Check out the Buffalo Bore .40S&W Outdoorsman, it's what I would carry in my M&P40.

I have some of the 200 gr .40 I carried in my G22 at my old deer camp.   Shot a hog with it once and the hog just took off running.   Unless you get the very lucky shot stopping a wild animal with a hand gun is pretty fruitless.    You may wound it mortally but it can do all it's damage to you before it dies.  I carry a pistol in the woods for wild 2 legged animals.

Just stick with the 9mm.   Get 147 gr FMJ and you'll have more penetration than the .40 200gr rounds if you're worried about it.  

Most animals go down without much fuss but some don't, like hogs.  I don't care if you hit an adult hog with  9mm or a .44 magnum, if you don't get good placement (central nervous system) or break it's legs, it's going to run, that doesn't apply to every critter out there though.  Penetration is the thing you need when trying to stop critters from munching you.  You want a cartridge designed to penetrate and break bones and crush and tear tissue to make it physically impossible for that critter to get at you.  The more power behind that bullet the better.  A hard cast bullet in a 9mm is not going to penetrate into and through a big critter with the same energy and mass as a .40S&W just like a .40S&W isn't going to penetrate into and through a big critter with the same energy and mass as a .44magnum.  We aren't talking hollow point expanding bullets designed for humans, we are talking ammo to stop big animals from getting close to you.  If a mountain lion is crouching to pounce on you you want a big, fast moving hard cast bullet with massive energy behind it to punch through big bones or skulls which is a far different comparison than the 9mm-.40S&W-.45acp in geletin one.

The .40S&W cartridge I recommended was specifically designed to penetrate deeply and break bones of big animals that are trying to eat you.  If you think you can get the same results from a JHP 9mm, you've seriously misunderstood the point here.  There are hard cast 9mm rounds made for the same purpose but they don't have the capacity to create the power a .40 can just like a .40 doesn't have the capacity to create the power a .45 Colt has and so on and so on.  However the shooter in question can't handle the recoil of a .44 magnum or a .45 Colt high pressure caliber so she needs the most power she can get and still be able to handle and shoot effectively.  Hence the suggestion of the .40S&W M&P40 with the standard pressure Buffalo Bore .40S&W Outdoorsman...a caliber/gun/cartridge combination that can stop big critters without excessive recoil.

The OP's situation is for day hikes or a companion sidearm while hunting in Oregon, where you might occasionally come across a cougar, black bear or (more likely) a two-legged critter. These type of threats simply do not fall into the same category of "big critters" where you need to be able to punch through big bones or skulls. One good shot from a modern centerfire pistol will turn a cougar with ease.

Yes 40 S&W would totally take care of business while 9mm would just make an animal mad

Shot placement > 9mm, 40 S&W, 45 ACP, 357 Sig

Like a chimpanzee.  If I see a chimp it's weapons free.  

I vote an AR pistol with a single point sling for her....

In my itty bitty girl opinion, 45 is easier to shoot than 40. I still prefer to carry my G19 in hog filled woods tho. I'm actually more worried about the humans there, anyway.

DoubleTap makes a the best 200gr design for the .40/10mm, it's a 200gr WFNGC hardcast that they claim runs 1100 fps from a 4.5" G22.   You'll have good penetration with that load and that's what counts, assuming proper shot placement that is.

My daughters carry Glock 19's or SW SD9VE's when they are out at the ranch. They are loaded with either Winchester 115 grain JHP or Federal 124 grain Hydrashok. The worst 4 legged critters they may run into while out there are feral dogs or hogs. Either a hit or the noise from a 9MM will send these scurrying. It is rare, but not impossible for a mountain lion to be in the area, but I am sure that a 9MM will definitely change its mind that my daughters are easy prey. My son is the one who insists on carrying a 686, but that is loaded with 110 grain JHPs. A good all around load for .357.

She should be fine with 16 rounds of 147 grain JHP. If we lived up in there, then I would probably go to a heavier bullet, but down here in South Texas, those lighter rounds have served me well.

I don't see any reason to get her a 40 if she already has 9mms.  Using good ammo, the difference between the two on an animal will be negligible.  I have no doubt she can shoot a Glock 23 just fine (my wife does), but I see no reason to spend the money on another gun unless you're just looking for an excuse to buy something new.

I already have a g23... I wasn't planning buying any guns, just spendy ammo

Are there animals in the woods where you go that are more difficult to put down than humans, like bears or chupacabras or something? Also, the 40 SW in a glock 23 is a bit "snappy". How experienced is your wife? The gun she shoots the best (hitting the target quickly and repeatably) will always be better than the gun that she can't hit with or is afraid of. Again, I don't know your wife.

I would stick with the g23 and regular carry ammo.  Any funds spent should be for practice on drawing and shooting quick.  I have and carry a g22, xd40 sc and a Kahr P40 and feel comfortable in the woods with them all.

I would have her stick with the 9mm.

You might want to take a look at the M&P 45 Compact.....plenty of good loads available, and it's a soft shooter. With the small back strap, might be a good fit for her......