21.1 stem?

Yesterday I tried to fit the stem in a Reynolds 531 frame and I noticed the stem didn't fit for about 1mm.
I searched on the internet and I think what a need is a 21.1mm stem.
Does anybody know where I can find one?
Also, I read that some people have sanded a standard 22.2mm steam down to 21.1.

Any ideas?

thanks

i have a 21.1 old school bmx stem if its appropriate for what you wanna build.
exc cond £10.
sanding down stems is very time consuming!

fucks sake - I hate to be a pedantic bastard but this thread is in the wrong place

Thanks overandout but I'm looking for a vintage stem, like the standard 22.2.
I don't think a bmx stem would look right on the bike...but thanks anyways

I was going to say that this was a French standard issue, but I don't think it is. Standard is 22.2, that is correct. There is a French standard at 22.0, 22.2 stems are often sanded to fit.
As ever, Sheldon Brown (rip) has the information:
http://www.sheldonbrown.com/velos.html
http://www.sheldonbrown.com/velos.html#stem

Worryingly, I am using the "death stem" on my fixed gear... hmmm.

the tricky part of sanding the stem down is to do it evenly, otherwise it can crack, so I’ve been told...

It's a BMX stem.

Is it an old Raleigh?

I'm not sure; the frame only has a sticker that says Reynolds 531.
I think the problem comes from the fork...