A couple of us used 00 Buckshot (SG) on a pig-culling trip a couple of months ago. I am a convert.

I had a few bad experiences with buckshot failing to stop large boars in the past, but most shots during the cull resulted in one-shot kills. A couple of large boars I killed were noteworthy: the first caught the pattern of SGs on the shoulder at about 25 yds on the trot, all nine pellets hit, one was a pass-through! Another large boar was hit in the head as he bolted past me at full gallop, kicked out of a patch of bushes by my hunting mate. The distance was maybe 20 yds. Feel free to count the pellet strikes yourself!

My shots were made with Winchester 2 3/4 inch standard SG Buckshot (in the old red-and-yellow box), but one of the other hunters on the cull preferred the 'high-velocity' stuff in the silver box.

The critical element for success with buckshot is limiting the distance to maybe 40yds IMHO, but pattern your gun to determine at what distance the spread exceeds perhaps 45cm, and that should be your maximum range. More choke does not necessarily mean tighter patterns with buckshot.