Tron,
I am crying tonight! I have a new Winchester rifle for elg hunting in 6.5 x 55 SM. I just looked in my brass container for that calibre and found 200 pieces of Winchester brass with head diameter of 12.05mm, and 500 pieces of Remington brass with head diameter of 12.04mm. Is your Lapua brass 12.20mm?
Since this rifle is just for hunting I will load the american brass up and throw it away after one firing. I don't think case head stretching is a good idea. I will use Lapua brass only from now on in this calibre.
Does Sako make a good 6.5 x 55 hunting rifle? We can't get that calibre in a Sako here in the USA, and I have always wanted one.
Good luck shooting

Yes, lapua and Norma brass is 12,20mm (actually, they are often 12,15/12,16mm but still..)and you should not use 12.05mm brass unless your rifle has chamber that is this thigt. That would mean a chamber that would not accept correct 6,5x55 brass and a rifle that should be returned to the manufacturer.

Tron

I believe the Finnlight is available in 6.5x55. I'd like one too!
Jeff

MHO,
You're right. I'll start saving for a Sako hunter in 6,5x55. Remington and Olin must be trying to stretch regular.473" head size brass to fit in Chambers designed for .480" brass. I wonder if you can hear the case rolling around in the chamber when you shake the rifle?
JCN

I just measured my PMC 6.5x55 it's .474

OK,
I talked with some guys who know a lot more than me about the politics of rifle brass today. That's not saying a whole lot, but here is what I was told:
Most shooters don't reload. I know, awful, but true. SAAMI sez 6,6x55 SM brass should be .480" at the head. The brass is allowed to be up to .010" smaller across the head and still be in SAAMI spec. My Winchester and Remington cases at .474" are well within spec. My PMC loaded ammunition at .476" is closer. My Norma loaded ammunition is .477", closer still. You can bet that the American rifle chambers deviate from SAAMI spec in the opposite direction, i.e. they are cut to a generous size. Tight ammo, loose chamber. I am told that this is not dangerous. After firing there will be an unsightly flaring out of the case body just forward from the web. People who don't reload (the majority) don't notice and don't care. I care some, because it does shorten brass life some. With 700 cases for a hunting rifle I will find something else to worry about though. When I get my Sako will I use Lapua, Norma, or RWS brass? Yes. I like the idea of a closer fit between cartridge and chamber. If I ever pop for a 6,5x55 SM target rifle (or barrel for my Blaser LRS2)I will insist on Lapua.
I have three .308 target rifles. I use Norma in one, Lapua in one, and Winchester in one. Why? Glad you asked. The Sako TRG gets Lapua, and the Blaser gets Norma. Since I am not the brightest person on the firing line this way I always know which case goes to which rifle. The M1A gets Winchester brass because it holds up okay and doesn't cost much. That is important because the M1A beats the crap out of it.
I try not to get too fired up about the cost, though. If I was a truly thrifty person I would not have two safes full of guns and a house full of reloading presses.
Have fun,
JCN
PS Here is another trick I learned the hard way. If you want a pretty accurate rifle you can buy a Remington or Winchester and have it trued, rebarreled, re-bedded, trigger job/replacement, new stock, etc. Sometimes they shoot well from the factory, but not always(usually). Now I just buy a medium to upper end European rifle and go to the range. The cost is about the same, but it is quicker. Hope I didn't just piss in anyone's Post Toasties.