School me in 22 chambers

[Maple57]

Much is often made of Eley match .22LR ammo having rim thicknesses that average less than it does with Lapua. The result is that some shooters insist that a tighter headspace works better with Eley match ammo. But it's worth remembering that all .22LR match ammo is designed to meet CIP and SAAMI .22LR ammo specs.

Headspace is probably not as significant a factor with regard to accuracy as many might assume. Bill Calfee, the sometimes controversial rimfire gunsmith, said "If your headspace is safe, and if you have killer ignition with it, the headsapce [sic] itself, no matter what it is, has absolutely nothing to do with rimfire accuracy... I recommend setting HS at .043", with the ammo we have available today.....same as I've done for years now...."

According to Calfee and others, what's much more important than headspace with regard to accuracy is the length of engraving.

The problem with the length of engraving is one of competing objectives where too little engraving may not shoot as well and too much engraving either will not eject a live round or in worst case leaves the bullet in the chamber.

For PRS shooting, reliable extraction of a live round would appear to be a priority above all out accuracy, and that will change depending on the bullets used.

 

[RabidM4U5]

So the real question I ask all you shooters what is your Chamber spec of choice? For PRS shooting not single shot bench.

To that end, if I were to build a PRS rifle I'd probably be looking at the Anschütz spec chamber and increasing the engraving about 0.01"-0.02" more than they cut their chambers at the factory. I use Anschütz rifles in Silhouette shooting. Feeding and extraction is reliable, and you know they have a reputation of good accuracy (better than I can hold while standing, that's for sure!). Lilja II might be comparable, and the Ravage chamber was pretty much designed for PRS. I'd steer away from the Calfee, Eley EPS, and Win 52D chambers.