Tomcat squirrel success and failure, a tale of CO2 and the cold

[glyconny]

I had the day off on wednesday and decided to take the Tomcat out for work.  I've been putting in some serious time in my basement range with all my airguns, and have been experimenting with different things on the Tomcat.  I removed the scope (mounted it on the 1322) and put on a laser sight.  The Tomcat is unbelievably consistent and accurate, and the laser sight was easy to install, and just as easy to sight in.  Within minutes I was producing dime size groups off of a bean bag rest at 10 yds.  
The weather here has been cold, we got snow on mon.,  but wednesday was relatively warm, 55 degs., and sunny.  The squirrels, again, are in full fatten up mode and making a fairly regular habit of going through my garbage.  So it was a work day for the Tomcat.  I sat and watched my garbage with a coffee in hand, and was shortly rewarded with a plump squirrel sneaking onto the top of my garbage.  With a scope, I would've taken the shot from the window ( about 25 yds.), but seeing as I had just installed the laser sight, and knowing this was beyond what it was sighted in for,  I decided to practice a bit of stalking.  I got within 15 yds. and placed the red laser on the fusebox and squeezed the very light predictable Crooked Barn modded trigger, the gun silently sent a cphp to it's target.  The plump one fell from the garbage, did a little dance and expired.  The shot placement was perfect, and the cphp went all the way through.  
The next day I decided on culling the treerat herd a bit more.  So I did exactly what I did the day before.  The only difference is that it was 20 degs colder at 35 degs.  Well I knew that the cold would negatively impact CO2, but reasoned that at within 15 yds. it wouldn't make much of a difference, boy was I wrong.  A very similar opportunity as the day before presented itself to me, and I followed the same steps and again got to within 15 yds, lined up the laser and let fly with a cphp, and hit home, or I thought I did.  I heard the familiar pop, sort of saw the pellet find its mark, and watched as the treerat flipped a few times in the air land on its side, and.........GET UP and run to the nearest tree.  The squirrel was now about 20 yds away.  I quickly reloaded, got to within 12 yds, as the squirrel just sat in the tree about 10 ft up.  I could now see the spot that the first cphp hit, a bloody spot right at the base of its neck.  I no longer had a good backstop but at this distance I felt very comfortable in my ability to hit my mark, and felt like I needed to make an effort at humanely dispatching the squirrel.   I decided to go for the clearer easier shot and go for my trusty shoulder shot.  I fired again, the squirrel fell from the tree, got up again and ran off over my fence where I lost track of it.  
I'm fairly certain I hit this thing 2 times at very close range and didnt anchor it.  Only thing I could think of, aside from that I just missed, is that the cold had a bigger impact on CO2 then I thought it would.  So I took out the chrono, and was surprised at the results.  The Tomcat chrono'd in my basement where its about 68 degs at an average of 562 between shots 3 and 15 which  is good for a little more than 10 fpe. The results outside at 35 degs was an average of 372  between the same shot counts, which cuts down the fpe to 4.395.  I'm shocked at the steep drop off, and have learned a valuable lesson.  I guess the CO2 stays in my range until it warms up above 55 again.

[shadow]

Nice shot on the nutter with the pistola Glyconny, great pic also. Bummer that the other got away and hopefully another critter got him due to his injuries. The C02's don't perform their best at these lower temp's that and squirrels are tough customers for their size.,he may still be limping around and you'll have to finish the job so look for a limping nutter. Ed

[glyconny]

Thanks Ed.  I tell myself that the nutter got by on adrenaline, and quickly died after running away.  I'll keep a look out though.  I knew that cold temps had a negative impact on CO2, but was surprised at what the numbers bore out. That's better than a 30% drop in velocity, equating in a greater that 50% drop off in fpe.  Also looking at the previous days result at 55 degs. where I put a cphp completely through the head of a nutter, without chrono #'s at that temp, I'd have to guess that there's a steep drop off in velocity somewhere below 55.  Live and learn, no more CO2 below 55 for me.

[only1harry]

Good shooting with that nice Tomcat pistol!  

I think most of us have learned a lesson or two with CO2 guns in the cold.  My 850 .22 dropped from 610fps down to 530-540 in 35deg. weather but I had kept it by the radiator for an hour or two before I ran outside with it to go after a crow.  So it was probably shooting 620 or more because it was nice and toasty :)  I stalked the crow for a couple of minutes.  The pellet dropped a couple of inches lower from where I was aiming at 30yds and missed the crow.  I came back inside and put it through the chrony and was surprised how much it had dropped in a few minutes outside.  

It only takes 4fpe to kill a squirrel and if yours was shooting 4.5-5fpe, at 12yds a shot to the head should have done the job or seriously wound the squirrel where he couldn't run away, and allow you for a better or closer follow up shot, in the worse case scenario.  I 've killed several squirrels at 10-15yds with my 5fpe (maybe 5.5 at the most) 760 pump, many years ago with head & neck shots further up near the head.  I always used pointed pellets for better penetration.  A shot to the shoulder (bone) with reduced power, is not the optimal shot.  The shoulder bone will stop the pellet short, but in the head it will cause serious trauma and disable the squirrel even if it doesn't kill him right away giving you a chance for another shot or just wait until he expires (sometimes 30-60 secs with a 5fpe gun).
Don't worry I think we 've all been there with CO2's!  :-)

[glyconny]

Yeah Harry you're right, at that kind of fpe a head shot is the only way to go, especially when you take into account the extra padding the nutters are carrying around this time of year. I just didnt think my velocity would drop off that much.  I did a little resarch and found a great calculator on the Air Rifle Links and Demo page http://www.arld1.com/  on how temp affects CO2 vapor pressure, and with the numbers i plugged in the drop in PSI was indeed more than 30% between the 2 temp variables.