![]() ![]() I'm a member of rimfire forum, but I can't recall the last time I was over there. Long barrel mass certainly slows muzzle change of position due to muscle twitching or trigger slapping and the rest. But it could also be that if all the rest is the same, the simple fact you have more barrel mass extending out further is reducing muzzle rise around the recoil moment of inertia, and so the gun, overall, just moves less. If it is scoped, it could just have more optimal bore dimensions and the like. ![]() If your 28" barrel is always more accurate and you have iron sights on it, then the sight radius explanation is a good one. Dropping your eyes to the second table you see the 22" Kimber actually shooting them all a little faster, and the 23" Winchester showing a little loss. In this study of 22 RF rounds from the Ballistics By The Inch project, you can see the 40-grain bullet loads show no significant change in velocity between 15 and 18 inches, and the Aguila 60-grain sub-sonic doesn't change significantly between 11 and 18 inches. Bottom line: friction is generally on the downtrend in later barrel travel, so velocity losses are small. Friction due to pushing (during accelerating) or dragging (decelerating) against the radial surfaces of the rifling changes with those rates of change in velocity. Friction due to lube viscosity, will drop with velocity. This portion of the friction thus declines with pressure. The reason is that friction force is partly determined by pressure upsetting the bullet outward against the bore. Slowing just means force on the bullet base from pressure is dropping below the opposing force of friction, but this drop-off is very gradual. While the bullets do start to slow past 16-19 inches (depending on the load, according to Geoffrey Kolbe), the pressure behind the bullet doesn't just vanish. I suspect the sole exception to this might be where the distance is far enough that the subsonics simply would be falling out of the sky before the supers. Still, in absolute calm conditions, I've never been able to match accuracy with supersonics with subsonics consistently. There's a caveat-supersonics are a bit more "environmentally resistant" when it comes to the presence of any kind of wind and also ease of trajectory adjustment when going long. I personally have never been able to match the accuracy/consistency of the best factor match grade ammo with any supersonics, including handloads of high BC bullets. There are two camps on this subject as well-those that maintain that supersonics are superior-especially at longer distances-than subsonics, and those that say subsonics are the most accurate. I've also used projectiles that have better center of gravity and BCs than traditional 22lr round-nose/hollow-points. Supersonic vs subsonic ammo-I've experimented quite a bit with this, using both factory ammo and my handloads. I've also read anecdotal evidence on the 22lr forums that participants and winners at 22lr comps are rarely, if ever, observed to have used short barrel rifles.Ģ. My personal experience coincides with the latter, though I can't say for sure why. I've read about the physics of this on some forums-including thoughts by professional ballistics experts-and there seems to be two schools of thought the first being that increased length does nothing but slow the bullet down, and a second thought that the increased travel down the barrel "smooths out" the stability of the projectile prior to muzzle exit. I personally have never had any shorter barrels equal the consistency and accuracy at any distance equal that of my 28" tube. Top velocity is attained at 16" +/- so most commercial accuracy barrels and rifles are sold in 20" and less length. Barrel length-I have 3 different barrel lengths from 16" to 28". I don't claim anything is a commandment handed down from Moses.ġ. So, I'm going to venture out and propose some personal observations that are based on nothing more than personal shooting experience and info gleaned from on-line forums. ![]() I guess most serious rimfire addicts eventually end up on rimfire central. 22lr is a bit of a cult-used to be more shooters here on this forum that discussed it but that group has seemingly dwindled (partially due to stiff resistance to creating a separate rimfire subforum IMO ). ![]()
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