Your small one probably is a .40 caliber, sir.
At my peak, I could impale a cigarette butt with 3 darts in a row at 10 meters (official distance in a blowgun tournament).
In the right hands, a blowgun is a very serious weapon.
When I was still in Asia, I met a native old man in his 70s who was also very proficient with the aforesaid weapon.
He used his blowgun to hunt birds and monkeys.
He never did disclose to me what type of poison his tribe used for hunting big animals but they also used the same when they were up against other tribes.
It must be identical to curare.
I did buy his blowgun and gave it to one of my friends as a present.
It was made of Bagakay, a thin variety of bamboo.
Check out this guy's blowgun:
His appears to be a .70 caliber.
I have tried this caliber before with footlong bamboo skewer darts attached to vinyl cones, and it beats the the .625 caliber in penetration and distance by a large margin.
The dart would make a very audible popping sound as it makes egress from the muzzle, sailing beyond 200 feet/66 yards with ease.
I am an accomplished blowgunner when it comes to power and accuracy but these natives' lung power would put mine to shame.
Btw, when I did rat-hunting, I would lace my tips with Siling Labuyo, a small chili with a Scoville unit of about 80k to 100k.
The pain would shock them senseless
I would notch (multiple cuts like a fish scale) my bamboo dart tip section with a sharp blade so as to prevent it from dislodging when they try to escape into holes and tight spaces upon penetration--try to imagine being pricked by a Cactus plant with those miniature barbs,
If you hunt big animals like a raccoon, try to Google Foxglove plant (the USA has them), as you can boil it, roots, stems, and all, until it becomes slurry.
It will cause paralysis if you dab your dart tips with it.
Take note: I am not condoning the use of poisons but it will lessen the suffering of your prey if you are unable to give them a killing shot with an untainted dart.
Foxglove is also dangerous when ingested.
Capsaicin, a spice that over a million Scoville units, is also a very good alternative.