Silly thought from a new guy

What if!
Airgun barrels were truly standardized to inside diameter(i.e., 5.52 for .22) aaand...
Pellets were made sabot style so standardized barrels could seal better aaand....
Eliminate pellets moving down that barrel inconsistently.
I mean, they do it with rifled shotgun barrels....
Just wondering. Is that over-engineered? Am I musing on something that does not need solved? Would that make things too costly?

Cannot help myself. I am wired to ask questions about stuff like this....
 
Pellets are remarkably tolerant of modest variation in barrel land & groove diameter, on account of two key features:
  1. minimal contact area - just a small band at the head and at the skirt. So long as the head is large enough to "ride the rails"--meaning skating along the tops of the lands--it is sufficiently supported and will not tip in the bore. Likewise, if the head is 0.001" or 0.002" larger than the lands, it will readily accept the engraving from the lands and be similarly supported in the bore.
  2. skirt obturation - pellet skirts are deliberately oversized by a few thousandths, and the pulse of high pressure air causes them to obturate (puff out and conform to the land/groove geometry) and produce a gastight seal.
So for example, a .177 barrel can have lands of 0.175" or 0.176" or 0.177" and be capable of shooting many different pellets well. Holding a tolerance of -0.002 / +0.000 is pretty trivial even for cheaply manufactured barrels.

Slugs, however, are a very different animal. Dimensional matching is much more critical.
 
Pellets are remarkably tolerant of modest variation in barrel land & groove diameter, on account of two key features:
  1. minimal contact area - just a small band at the head and at the skirt. So long as the head is large enough to "ride the rails"--meaning skating along the tops of the lands--it is sufficiently supported and will not tip in the bore. Likewise, if the head is 0.001" or 0.002" larger than the lands, it will readily accept the engraving from the lands and be similarly supported in the bore.
  2. skirt obturation - pellet skirts are deliberately oversized by a few thousandths, and the pulse of high pressure air causes them to obturate (puff out and conform to the land/groove geometry) and produce a gastight seal.
So for example, a .177 barrel can have lands of 0.175" or 0.176" or 0.177" and be capable of shooting many different pellets well. Holding a tolerance of -0.002 / +0.000 is pretty trivial even for cheaply manufactured barrels.

Slugs, however, are a very different animal. Dimensional matching is much more critical.
Being that amount mass produced i think pretty darn good tolerance kept. Some just a bit better than others.

 
Last edited:
No doubt, pellet consistency is vital to accuracy. Emphasis on consistency over some specific head measurement. So for example I don’t really care if I order some pellets and receive a tin whose heads measure 0.176” or a tin that measures 0.178”, as long as all in the tin are consistent. And by consistent I mean in every conceivable way…pellets all from the same die, fully formed, geometrically and gravimetrically uniform, symmetric about the center axis, absent of flashing or other molding defects, made from a uniform alloy, undamaged from rough processing/shipping/handling, etcetera, etcetera. Consistent head sizes are merely a useful indicator of consistency more generally, but by no means a guarantee.

In contrast, my barrel simply is what it is. Say, 0.175” lands and 0.180” grooves. It stays pretty consistent I think :)
 
  • Like
Reactions: DesertSilver
Yea Hateful Mc Nasty, I follow same advice. That why I will always use a thumb loaded barrel for competitions. You can feel a cull easily. I also have a tiny lens on my key chain. I can use it to magnify a pellet for inspection. The lens is flat but acts like a loop lens.
Same gun, same pellet over a long time you kinda got the "feel" of it