Fireforming 22-250 in a 22Creedmoor chamber

[Ironworker]

I found the hard way the 22 CM is a slightly different case then a 22-250. Case head above the extractor groove on 22CM is .4703, on the 22-250 its. 467.So before knowing this I fired some 22-250 in my 22 CR chamber. On the fireformed brass there is a step down on the base just above the extractor groove. The ammo shot good. So, I loaded up new loads in the now 22 CM case, they chamber rough but extracted like butter. But they shot good. My question is am I risking a case head separation? Did I ruin some lupua and Norma brass?

 

[Shotafterdark]

Don't do it ...the 22 250 case is just too small in web and height at shoulder
It' stretches but it's compromising the case ..
Use readily available 308 brass ...neck down in a 6.5 Creed
Then a 6 Creed and then the 22 Creed for a much safer alternative....

Cut the 308 to an OAL of 1.950" to start then chamfer inner and outer neck
Then proceed with plenty of Lanolin ..
works like a dream ,,,

 

[Fast14riot]

Yeah, not compatible. I tried sizing 6cm brass down to 6x250 and due to base dimension it was not possible. Also, look at the extractor groove of the two, very different. In short, don't do more than once. Creedmoor brass is plentiful and cheap.

 

[clowdis]

Even fireforming 22-250 to AI will leave a small step at the shoulder. I've shot these cases a lot with no further deformation. I think they're safe but like they said above, 22 Creedmoor case are available so why not get those.

 

[Ironworker]

So dang now I've ruined some Norm and Lupua brass. Life goes on. Thanks everyone.

 

[AlNyhus]

I use Lapua 22-250 brass in my 22 Creedmoor. No problems whatsoever after many firings.

 

[Ironworker]

I use Lapua 22-250 brass in my 22 Creedmoor. No problems whatsoever after many firings.

Do you have that step down above the extractor groove?

 

[AlNyhus]

Do you have that step down above the extractor groove?

There's a very subtle change....certainly not a 'step', though. The virgin Lapua 22-250 cases I have measure .4680 by a Mitutoyo micrometer. Fired brass at .200 ahead of the extractor groove measures .4710.

It's likely that your chamber might be a bit generous at the back end. Is this a custom chambered barrel or a factory barrel? -Al

 

[Ironworker]

It's a custom chambered barrel. I'm going to scrap my fireforming and stick with 22 CM brass.

 

[White Eagle]

there is some really good 22 Creedmoor brass
why not use that ?