Hmmm the problem as I see it is defining "small Deer". Here in the UK .22 Centerfires are legal for Roe Deer only providing they meet these specs:-
Min 50 grn Bullet
Min Muzzle enregy 1100 ft lbs
Min muzzle velocity 2450 fps
Nowhere else in the UK is this legal the legal minimum being .240" cal with min muzzle energy of 1700 ft lbs.
Now Roe are Small deer, a big Buck may reach 60 lbs but more likely being around 50 lbs with Does being lighter still however saying that Roe are lost each year due to poor bullet placement or bullet reaction. A gamekeeper friend spent 4 hours bringing a Roe Doe to book as it was acting strangly, a couple of hours watching it before he noticed a spot on her side, she was in poor conditon it looked like as she was in the middle of a large field with no way to approach closer to get a better look. So he decided to cull her.
When he got the the dead beast he found his bullet hole (using a .243 with 100 Grn Fedral perium ammo) about 1" away from a small .22" size hole which on examination had passed through both lungs. The exit side having a slightly larger hole and she was badly maggot infested on the entrance and exit under the skin. She was literally being eaten alive 
.
Depsite a good hit penetrating both lungs the .22" bullet did not do enough terminal damage to drop the Doe. He for one has seen this too many times and does not advocate the use of any .22" cartridge on Deer.
So what was the cartridge, Muzzle velocity & bullet used here. 22 caliber may mean a 22 hornet, bullet may mean fmj (if the bullet was not found we don't know & may be reason for small wound channel). If we don't know what was used, what possible conclusion can we draw? And what are these other wounds the Warden
refered to? The rules indicate some small round is being used by someone, 50 Gr. Min, 1,100 ft. # of energy
& muz. vel. of 2,450, well the energy is close but the other numbers are way off, more like a Hornet or something.
I just don't like conclusions being drawn based on information that doesn't apply, which appears to be the case.
If anyone thinks this means that I advocate the usuage of the 223 for Deer, they would be wrong. The guns that I use for Deer begin at 25 caliber, I know the 243 works, but I prefer bigger rounds. And yes, the 223 will RELIABLY kill Deer, even large Northern types. Does this sound contradictory, yep! Is it, nope!
The conditions at which this is 100% lethal is much more narrow than using a bigger round, which means like bow hunting you will have to turn down opportunities that could have been enjoyed with a bigger round.
I know of about 200 Whitetails that have been harvested with the 223, 1 friend killed 114, another killed 50-60 Deer, Me & my brothers have taken about 18 (experimental days). The man who killed 114 is a great shot & woodsman, he did not lose any, he is brutally honest. Myself & my brothers did not lose any & we used
one shot per Deer. The other guy that took 50-60, I know he lost one & he may have lost another, Its been a few years & I am not sure, so the ratio is good compared to others I am sure. But the Deer were shot under certain conditions as follows, & BTW, some of Deer were Soybean fed Black River Bottoms Bucks, 1 @
210# & a few others that general size & most were 125-150# Deer.
Here are the perimeters.
A 55 Gr. Soft Point bullet like the CoreLokt, Powerpoint Horn, etc., 53 Gr. or up Barnes TSX, 60 Gr. Nos. Part,
60 Gr. Horn. Soft Pt. the Swift or 55 TBBC, 65GK & some others, placed behind the shoulders to do a double lung shot (like a bow) & done at 75 yards or less (most woods shots) with a decent muzzle vel. will mean Deer steaks & this includes Big Bucks. A 250# Buck will not have rib bones twice as thick as a 150 # Buck, they will be thicker & wider, these bullets will go through that every time & destroy the Lungs, again if you use these bullets, load a good velocity & keep the range some. In other words, broadside shots & a minimum angle, in other words you want to penetrate both lungs without hitting the shoulder first, a no-no on a Big Boy.
If you for some reason need to shoot a 223, do it under these conditions. Most tree stand shots will allow this, but not all which goes back to using restraint.
This brings about the reasons I don't Deer hunt with a 223.
(1) Angles--- I place my stands where most shots will be broadside, but not all & the Big Bucks seem to be
more unpredictabe than the others. I want a round that I can place my bullet at the point of the shoulder facing me if I need to or slip a bullet in at the rear of the vitals & angle up to the far shoulder if the Deer is
standing at such an angle. I can do this evevy time with the rounds I use, I would have to pass on these
with a smaller round, unacceptable if the biggest Buck of the year seen was one of these!
(2) Distance---- Don't want to get into long range at all here but if I see a Deer I want at 300 yards or my personal maximum range (not going to say what that is) or even 200 yards, I want to take advantage of that
opportunity. The 223 has the flat traj. but not the bullet weight, retained velocity & energy to do this. I consider the max distance to be 100 yards to give a devasting wound channel & 75 yards and under is better.
Again, this would mean an occasional missed opportunity.
(3) Obstructions--- No, I do not believe in brush busting or thinking that I am using a round that bores through
brush reliably, what I mean is occassionally you may hit a small limb right in front of the Deer, it won't be a problem for what I use, but with a 22 cal, it could.
(4) Bloodtrail--- Seldom a problem if you shoot them under the perimeters I mentioned as they just won't go far, but if you shoot one at the edge of a Southern clearcut, it may take a while to find if the bullet doesn't exit, here I would use the TSX ofr Part. Some cleacuts I have hunted, I had to crawl to fine the Deer & pull them out the same way, a bloodtrail helps & with my guns I get one.
I mention all of this in case there is a reason that you need to use this rifle instead of a bigger, more desirable round. It can be used with total success (the only way to be) but please understand the limitations & have the discipline to turn down ALL other shots. But if you have acess to a bigger gun, why limit your opportunities? Good Deer are hard to come by & you ASKED ABOUT SMALL DEER, but do you want to turn down big ones?
BTW, for the 1-9 twist I woud try the mentioned 55 Gr up to the 65GK.
Good luck!!
