Article on rim thickness sorting

[problemchild]

http://www.gun-tests.com/performance/sept96rimthickness.html

[BSlacker]

It is fine to sort by rim thickness. But how do you know which of the three sizes fits best in your gun. It would seem by their test that no account was taken of the actual headspace on the rifle used. It was just a Cooper so it is perfect. No measurement? Did I miss it? If the rifle has a headspace of .043"(common number in rimfire) few of the sorted rounds fit well. I think if you sort to fit your guns specific headspace then you will see a difference but they just sorted to shoot together the same rim thickness and compared to a different rim thickness in the same rifle but does one or the other fit better is never answered. You must know the headspace of the gun before sorting or it is a waste just like they found. No surprises here.

[sholling]

Interesting article thanks for posting it.

[sofbak]

Old article. Discussion came up on RFC some time ago, and I made my own rim gauge from a c-clamp and a 2" dial indicator

[IMG][/IMG]



My results were about the same as the article. Didn't do much to improve consistency....but ymmv.

[Press Check]

It is fine to sort by rim thickness. But how do you know which of the three sizes fits best in your gun. It would seem by their test that no account was taken of the actual headspace on the rifle used. It was just a Cooper so it is perfect. No measurement? Did I miss it? If the rifle has a headspace of .043"(common number in rimfire) few of the sorted rounds fit well. I think if you sort to fit your guns specific headspace then you will see a difference but they just sorted to shoot together the same rim thickness and compared to a different rim thickness in the same rifle but does one or the other fit better is never answered. You must know the headspace of the gun before sorting or it is a waste just like they found. No surprises here.

+1.

Without knowing the headspace, sorting based on rim thickness is absolutely pointless.

[BSlacker]

Competitive shooters shooting high end barrels and actions will know the headspace on their rifle. They then can sort for best fit. A snug fit is good for accuracy. Most shooters shooting bulk ammo need not sort. Once you get to ammo of RWS R50 or Eley Tenex Ultimate quality sorting is not going to help. Control over rim thickness is very good with the high end ammo. Your rifle will shoot the ammo or not. All the article did was find what rim thickness/ammo was good in that rifle. It should be titled How to find the best headspace/ammo combo on your rifle.

[donw]

at one time, i was weighing and measuring rim thickness of my .22 rimfire...lotsa work for the results in the end...no real noticable gain in accuracy