Friday, 5 March 2010

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
_________________________________________________________

22 comments:

  1. Great explanation, spot on.
    However, in defense of the .22, the trajectory can be tamed by a combination of a budget laser range finder and light weight .22 pellets (13grain Falcon Accuracy are fast at 620fps). For the hardier quarry such as a mature squirrel, the extra retained energy of the .22 comes in handy at 30y+.

    ReplyDelete
  2. Thanks Will - there's much to be said for .22. Tricky as the mental calculations can be to begin with, if you have a .22 springer there's no reason to think you can't learn how to shoot very well with it.

    I just noticed that this is the 177th post I've put on this blog. Mere coincidence?!!

    Well, yes - but a happy one, nonetheless.

    HH

    ReplyDelete
  3. N°177 and of the highest caliber...

    ReplyDelete
  4. I shoot a .20 to try to split the difference... punch and not as loopy a trajectory. I'm not limited to 12 ftlb here, but my budget and shooting taste combined to put me around 14 - 15. I use a laser and it all works out pretty well.

    However, I'm loving the idea of just shooting at the crosshairs and being done with it. So my next gun/s will be .177 -- which is why I asked the question. Your post is exactly down my line of thinking.

    Losing the laser except for long-range shots sounds like heaven to me. I like things nice and simple, which is why I shoot a springer instead of a PCP in the first place.

    Thanks for taking the time,

    Bp

    ReplyDelete
  5. Dear Rabbit Stew: to add to your many accomplishments and achievements, you have been honored with a Bloggery Award

    http://bipolar-stanscroniclesandnarritive.blogspot.com/2010/03/special-award-for-some-very-special.html

    ReplyDelete
  6. Hubert,

    I see that you've used the same sized kill-zone for both calculations (.177 and .22). In my experience, the kill-zone for a .177 shot needs to be smaller due to it's greater propensity for pass through shots. To be safe, I usually use .5 inch when determining the optimum zero on my .177 rifles.

    Also, 35 yards is apparently the wrong distance to zero the .22. Try moving it in and out until the maximum height of the trajectory just kisses the top of the kill zone.

    I think that if you do those two things, you'll see that the two pellets give very similar usable effective ranges. Theoretically, the .22 pellets will be more accurate at the longer ranges because they can fight the wind better.

    Of course, these suggestions are moot if you already have the gun and don't desire to switch :-)

    Cheers,

    Bobby

    "Take my advice, I'm not using it"

    ReplyDelete
  7. Bobby, I've been shooting airguns since god's dog was a puppy old friend. I've had many, many combinations over the years and come to the conclusion that although .22 is a good calibre for close to medium range, it will never beat the pure accuracy of a .177 at almost any distance. Believe me, I've tried and tried to get a .22 as accurate as I can, and spent countless money in doing so! But, sadly it is ever an equal. Thats why target shooters use it! As for it's killing caperbilities? I'm a professional pest controller and wouldn't use anything else. when you've got the owner of the premises where you are doing your job looking over your shoulder, you have to be pretty damn sure you can show you are earning your wages! I'll never 'knock' the .22, it has it's place, but like me any many others of people who rely on their gun and chosen calibre for a living, we are all swapping to .177. Incidently, most of the guys who I know who shoot .22 are mostly middle-aged, summat dating back to the sixties perhaps when .22 was a 'mans' calibre and .177 was for kids! Just a thought....

    ReplyDelete
  8. Great explanation HH.

    I carried out a series of tests myself recently along a different line, inspired by an article in "Airgun World" where you take a 30mm wide (approx rabbit head sized) chunk of shaped teracotta wax and sit it out at 30-35 yards. From here i used my .177 Air Arms TX200 mk3 and a friends .22 TX200 mk3 to fire pellets into the wax. The holes and channels created by the pellets were then filled with liquid plaster....once they were set they were taken out and their size inspected.
    The .177 Air Arms field pellets and JSB Exacts (standards not heavy's) left a larger wider channel wheras the .22 Bisley pellets left narrower channels thus indicating that the lighter .177's decelerated more on impact and while travelling through the target dumping more of their energy and so making a bigger channel.

    I will always opt for the .177 as a matter of choice these days, not only that, i've turned my back on PCP's. Yeah they are all singing and all dancing but i love the pure self sufficiency you get from a good springer and my recent TX200 mk3 purchase has got to be the wisest i've ever made from an air rifle point of view.

    ReplyDelete
  9. Thanks mate, a very interesting comment. A friend (Tony the airgun sage at Sandwell Field Sports, in fact) mentioned in passing to me months ago that he thought that rabbits headshot with a .177 actually bled more than did those with a .22. At the time I remember thinking that this seemed a bit unlikely to me but now that I've spent a bit of time in the field I do have to say that he was absolutely right about this and your (rather remarkable) investigation seems to bear this out as well. Thanks for taking the time to comment.
    HH

    ReplyDelete
  10. i have always used 22 infact for 20 years now i have had many 22 rifles my last being an hw 77 but on the last visit to my local gun smith i fell in love with the bsa lightning xl tactical i purchased 177 and i havnt had a 22 out since i am droping rabbits at 40 yards with no problems my freezer is full.I think its a combination of 177 pellet and ofcourse the lovely stock by hydrodynamics

    ReplyDelete
  11. Thank you very much for your interesting comment, friend!

    Cheers & happy hunting,

    Hubert

    ReplyDelete
  12. Thank you, great post. I am buying my first .177 after I have red.

    ReplyDelete
  13. Thank you, drevil, glad to be of help!

    HH

    ReplyDelete
  14. Am I made or is this just logic not really looked at?

    If you sight you .22 up to hit 15/30 yards to be in your zero elevation points of aim you would have a cognisant kill zone from 10-35 yards with in the one inch margin (1/2 inch each way) which would then simulate a very similar layout to the .177 graph that seems to suggest the .177 is better when set up right. I’d say the same for the .22 what you have shown is a .22 set up as a .177 so of course it’s going to suck.

    Sure you might miss out on the 40 yard shot but that’s getting a bit ambitious anyway, ideal range to kill rabbits is 30 yards is it not? Not so close as to spook them, and not so far as to miss. As said above I’m sure just set your rifle up for the Job and not assume one system of sighting up your gun to be the only one. As clearly proven with the graphs a .22 should be sighted to zero in at 15 and 30 yards. Not 10 and 40 yards which is clearly a .177 setup.

    ReplyDelete
    Replies
    1. ...but thanks for the graphs as now I know roughly what range I should be sighting up my .22 too... that’s a lot of 2's :)

      Delete
  15. Thank you mate, I'm glad you found it thought-provoking and (maybe) useful!

    HH

    ReplyDelete
  16. The post above us is correct I have my 12 ftlbs .22 zeroed at 25 yards with a 0.5 inch killzone and it's within that zone from 11-28 yards that means no more than 0.25 of an inch above or below where I aim over that distance. A .177 will do that 12-35 yards zeroed at 32. My point is they have a more similar PBR than the example above would show.
    That all said I if I was buying today I would probably get a .177, even at 50 yards it can still knock down a rabbit so the calibre is capable even if the shooter isn't :).

    ReplyDelete
  17. The issue is with the 12fTlb limit. With the same power available to drive either the .22 or the .177 then you can see why the .177 is better over the greater distance. You would need to increase to an FAC rated .22 to get the same muzzle velocity and range. In shorter ranges the added weight of the .22 is useful, think of it like the 9mm of a pistol round v the 5.56 NATO round.

    ReplyDelete
  18. Thank you, Anonymous, that's a very interesting comment. It's remarkable how many angles this question can be viewed from!

    HH

    ReplyDelete
  19. You images of the .22 setup show either intended bias or ignorance. This image I provide you is a much truer comparison and would better serve to educate people than your example.
    [IMG]http://i50.tinypic.com/2co4p4y.png[/IMG]

    ReplyDelete
  20. Hi Anonymous,

    Jolly good, many thanks!

    Best wishes,

    'HH'

    ReplyDelete
  21. The PBR of a .22 is roughly 6-31 yards (the correct air rifle hunting range) meaning you will hit within an inch kill zone in the cross hair in this range. After 41 yards you will need to apply the correct holdover to hit your one inch target.

    The PBR of a .177 is roughly 8-41 yards, 10 yards is hardly anything to shout about.

    One major point you seem to have missed is that .177 is more affected by wind than .22. Gravity is constant and a lot more predictable than wind which is variable, I know which one I would choose to master.

    ReplyDelete