Bullet jacket failures using heavy .224" bullets (88-95 gr) in F-TR .223 Rem loads has been a problem for some time. It has been compounded by the relatively long barrels (28"-30"+) and the fast twist rates required to stabilize the long bullets. There has been a trend in the last few years to go with a 0.219" bore as opposed to the old "standard" 0.218" bore. I waited some time to make the switch, largely because I had had several 0.218" bore barrels cut for my competition .223s and I wanted to use them up before ordering more. Once I made rthe switch, I can tell you that I do n ot see any reason to run a 0.218" bore barrel at this point, and will continue with the 0.219" bore barrels as the new "standard".
In my hands, the 0.219" bore barrels do not cause any loss of velocity whatsoever for a given charge weight. They also appear to lessen or mitigate the intial pressure spike observed during bullet engravement into the lands, thereby resulting in slightly lower pressure, even though the final velocity remains comparable on a per charge weight basis. That has meant a measurable improvement in brass life, which was noticeably poor with the loads I run in these rifles. Finally, jacket failures appear to have become a thing of the past with the 0.219" bore barrels. Of course, one can never say never, but I have been running heavies in 0.219" bore barrels with fast twist rates and at velocities that would have certainly resulted in jacket failures in 0.218" bore barrels.
As noted above, if one is running bullets in the ~80 gr weight range (length) or less, none of the benefits of switching to a 0.219" bore may be noticeable, especially with barrel lengths of 26" or less. Bullet jacket failures are typically the result of friction. The shorter bearing surfaces of lighter bullet classes don't seem to suffer from jacket failures to nearly the same extent as the 88-95 gr bullets. Barrels of 26" length (or less) also seem to remain below the friction threshhold required to instigate jacket failure. So it's likely if one is running bullets of </= 80 gr in relatively short barrels, the bore diameter may not really matter much, although there may be a slight improvement in brass life as I noted above. The caveat to that may be when running lighter bullets screaming fast, where it may be still be possible to cause jacket failure if the twist rate is fast enough. Nonetheless, as far as I can tell, the 0.219" bore doesn't appear to hurt performance in any measurable way, so the question then becomes, why not go with a 0.219" bore?
AFAIK - Bartlein makes 0.219" bore 5R barrels, which is what I've been using. According to their website, Krieger does not make a 0.219" bore .22 caliber CF barrel. Brux does offer the 0.219"/0.224" CF option on their website. FWIW - because the lead time for ordering barrels direct from the manufacturer can sometimes be pretty hideous in the current shooting/component buying environment, you might want to contact a barrel vendor such as Bugholes (aka Southern Precision). They may be able to order a barrel for you with a much more palatable lead time than if you ordered it direct yourself.
