Why a .177 over a .22 for Hunting Rabbits?

Bpaul wrote in a comment recently:

I'd be curious on the numbers your gun is putting out if you get a chance to shoot it over a chrony.

Also, your decision to go .177 from .22 -- did you blog about that? Be curious to hear why...

Hi Bpaul,

I went for all this, basically, because the opportunity presented itself and the argument about the flatter trajectory of the .177 finally convinced me. With the roller-coaster trajectory of the .22 at 12ftlb there's the constant difficulty of trying to estimate where the pellet will be in its arc when it reaches its target point.

If you zero at 35 yards with a .22 there's a variation over, say, 40 yards of about three inches up and down through an imaginary line from the end of the scope to the target. The pellet starts two inches below this line, climbs up to about an inch above it and then immediately after 35 yards drops below it again in its downwards fall. So there's a three-inch margin for error depending on where the target is and constant adjustments up and down need to be made in the reticule to accommodate this while aiming. (The graphs below are from ChairGun Pro available free here.)

With the .177 at 12ftlbs however, the arc of the lighter pellet will stay within one inch from about 10 right the way out to about 40 yards (.177 RWS Superdomes weight only 8.3 grains against the 14.66 grains of .22 H&N Field Targets). So in theory that means that if you can judge that the rabbit is at a distance anywhere between 10 and 40 yards then you can be fairly confident that a shot at the intersection of the scope's cross-hairs will result in a pellet hitting the target area. If you compare the length of the different pink kill zones on the two graphs you can see that they do bear this out.

My distance estimation is not so great but even I can tell if a rabbit is between 10 and 40 yards; so purely on the basis of this there's a much stronger case for going with a .177 for fieldwork.

To get the pellets out at anything up close to 12ftlb a .177 needs a spring with a few more coils on it than one in a .22 - and you can feel the greater effort needed to cock the rifle now. (The rifle was of course chronographed before leaving the shop and it was doing a healthy and legal 11.78ftlbs with the RWS Superdomes I'm using.) I've heard it said from people commenting here that with this stronger spring the increased release vibration in a .177 would act against any gain that the flatter trajectory could provide. This did seem to make sense to me but (and I can only speak about my rifle, of course) thanks to Tony at Sandwell Field Sports, if anything the gun now fires with perceptibly less spring judder than it did before the work was done.

My damn cold is still hanging around so I suspect I won't be going out today to see if all this theory on paper translates into a greater incidence of rabbit on the table - but I'm hopeful for the future.

Cheers,

HH
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Tags: accuracy, 177, air rifles, pellet, sandwell field sports, shooting, Springer, hunting, trajectory

The big question: .177 or .22 for Rabbit Hunting?

177 or 22? That - a swift peek at any of the popular airgun forums will quickly assure you - is most certainly the question.

To cut to the chase, the answer's 177.

Why? Well: it seems to boil down to trajectory - the parabolic path that a hopefully rabbit-bound pellet describes after it leaves the barrel of a rifle. It does not go in a straight line, I learned to my surprise, and then drop when it's tired - it inscribes, instead, an arc 'twixt gun and rabbit. But if it does that, then it's not simply a question of 'point and shoot' at all; distance becomes a crucial factor. How can you predict where in its arc your pellet is going to be when it reaches the head of the rabbit that you wish to shoot? Because if it's an inch too high then it will miss, and if it's an inch too low, then it will miss again. Nightmare!

177 pellets have a much flatter trajectory in the 40-odd yards after they leave the rifle barrel than 22's do. It's as simple as that. You can arrange it - I gather - so that in the area, say, between 20 and 35 yards (the crucial area within which the vast majority of relatively humane air rifle shooting is going to be taking place) the pellet will deviate from an imaginary straight line drawn between the end of the barrel and the rabbit's brain by a matter of only so little as half an inch or so. A 22 pellet, on the other hand, will be drawing a line that looks like the path of an amusing roller-coaster ride.

This I learned after I blew all the cash I had to spare on a 22 rifle.

If you want to have a gander at some parabolas, head over to http://www.chairgun.com/ or to the ballistic reticle calculator (superb name!) at http://www.hawkeoptics.com/brc/index.php and download the free software.

[In my time machine I revisit this post to leave a link to the future where I will write more upon this topic and my decision to opt for .177: http://austeritygrub.blogspot.com/2010/03/why-177-for-hunting-rabbits.html ]

Crosman 2250 Ratcatcher

I wish I still had the Ratty. I had to flog it to get the cash for a full-power gun that might at least allow me to get the odd, inattentive rabbit. Crosman air guns come from the factory as very basic but highly customisable guns and there's a giant network of people who specialise in building on the basic forms of the bog-standard Crosman. Here's a few links:

Crosman Airgun Forum (new)

Crooked Barn

Custom CrosmanParts and Spares

AirgunMod - Custom & Modified Crosman Airguns

Even six months later when I've learned a tiny bit more about stalking and suchlike, I'm still not at all sure that I'd be any use with a Ratty - even one with a souped-up range. The furthest I got into the world of Ratty-customisation was to get a set of springs which lightened the fairly hefty single-stage trigger pull and pushed the internal hammer a little bit harder in its flight toward the CO2 release pin - thereby releasing more gas and generating more push behind the pellet. So, more poke, but less shots per cannister as more gas was used in each shot.

My memory of using the Ratty after rabbits is this: I'm crawling between cow-pats, cold, slightly wet around the kneecaps and trembling with anticipation: there is a rabbit in the field ahead of me. I edge up to a steel fence and - trying not to breathe too loudly - edge the Ratty through the bars of the fence and plonk my head alongside so I can see through the scope with the gun pointing rabbit-wards. I wait - cold and nervous - while my breathing settles down and watch the rabbit looking around - he's presenting me with a perfect profile for a head shot and I'm aiming exactly at a point where an imaginary lines reaching back from its eye would intersect with one coming down from its ear, bang on the creature's brain for (what's known as) a humane kill. My breathing has settled, I'm spot-on on target so I squeeze the trigger and....

There's a 'phut'. The rabbit looks round, unperturbed and completely uninjured, decides that the present company is - by and large - unwanted and then proceeds back towards its burrow at no great speed.

In my excitement, I'd wildly misjudged the range and the looping trajectory of my heavy .22 pellet had resulted in it burying itself in the muck ten yards or so short of the rabbit.

I repeated this several times and started doing lots of searches on Google for "good air rifle for hunting rabbits".

Let me Google that for you.

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Tags: air rifles, crosman, Ratcatcher, hunting, rabbits, shooting, stalking, trajectory