"Hunting....... Break Barrel in .22 cal."
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Interesting point of view than many knowledgeable airgun hunters on my side of the big pond also share, but I haven't found that to be true for my R9 (rebadged HW95) springers. I started out shooting a .177 R10 and it served me well for all shooting, then I bought a .20 cal R9 and used it for a year for general pest control and tree squirrel hunting and found it a bit disappointing when comparing the "hit to retrieve ratio" conpared to the .177 bored R10. Then I bought a used .22 cal R1 barrel, sent it off for a chop and choke, then mounted it to the R9 and again was disappointed when comparing the results to the .177 R10. I ended up selling both the .20 and .22 barrels reverting back to .177 cal and haven't looked back.

My issue with the larger calibers vs .177 for tree squirrels was that the squirrels didn't drop any quicker when hit with "fat lead" than they did when hit with "skinny lead"! When dressing out the squirrels for the pan the squirrels that were double lunged with .20/22 pellets were indeed "busted up" more, but they traveled just as far after the hit as they did with a .177 double lung hit. I guess this didn't surprise me much since I've seen multiple squirrels double lunged with a 100+ fpe .22 rimfire still truck it quite a few feet before dropping, so I really don't put much stock on a piddly 14fpe hit!

I believe that the issue for ME and "fat pellets" is that the much steeper trajectory of the .20/.22 pellet from my 14fpe R9 made range/holdover estimation too critical past 30 yards for my skill lever, therefor I got too many "off the mark" hits with fat pellets. With my .177 R9 I can pretty reliably brain a squirrel in a tree at 40 yards so I don't see the point of hobbling myself with .20/.22 and 30 yard shots.

Two tree squirrels, one head shot, one double lunged with a single .177 dome....
http://img.photobucket.com/albums/v7...oSquirrels.jpg

What those squirrels were turned into.
http://img.photobucket.com/albums/v7...dSquirrels.jpg

Some bigger stuff also taken with a .177 dome include ground hogs (dome at base of skull severing spine)..
http://img.photobucket.com/albums/v7.../groundhog.jpg

And a raccoon with .177 dome behind the head as it was in a tree after wrecking a bird feeder.
http://img.photobucket.com/albums/v7...acoon_R9_1.jpg

Anywhoo.........my PERSONAL opinion is that penetration THROUGH the vitals trumps a bigger hole that doesn't hit the vitals and at R9 power levels the .177 penetrated better. Please don't take this reply as a rebuttal to your fine post.........take it only as a different point of view based on my PERSONAL shooting skills!