volume of gas generated by 22 LR

[PeterF.]

Anyone know the volume of gas (generally ... considering various brands  and types) by a 22 LR cartidge.  I've seen some discussions that suggest a very-long barrel might actually lessen accuracy because its internal volume is more than the gas generated by the powder ... so it is no longer pushing the bullet down the barrel.  Also, anyone know of either a ready web source of information on this (volume info), or a formula that might allow "backing into" the answer?  TIA.  Peter F.

[KN]

I don' know about the 22, but I believe it was Virgin Valley that did a test on the 17HMR and confirmed that optimum barrel length was 18"-19" for that caliber. Any longer and they began losing velocity. I trimmed my TC barrel to 18" and it works wonderfully. I would be surprised if a std 22lr round showed any increase in velocity after 16"-18".  KN

[Nobade]

.22LR maxes out at about 14 inches of barrel. So I often just cut them to 16.5 inches to be legal, for lightweight squirrel rifles.

[S.S.]

Nobade is correct 14 to 18 inches for a .22 LR.
The real purpose for some of those LOOOONG barreled
old timers was to give a longer sight distance for better
accuracy. Scopes pretty much nullify this. I would say that
anything over about 18 inches is wasted barrel.
Once the gasses quit expanding, the contact with the barrel
simply becomes resistance to slow the bullet down.