[Coenen]

Apparently after the barrel has been used for a long while or a hundred thousand rds or so, the barrel begins to wear smooth on the inside which lessens and finally negates the intended backspin effect. Tippmann will re-sandblast these barrels back to the original roughness inside for free as long as you pay shipping. Call them up an ask, or send them an e-mail and post the reply here for the benefit of all.

It should be noted that the A-5 Flatline relying more on the roughness of the barrel and less on the curve and length wears out more quickly than the Model 98 Version.