Just realised whilst wearing my new stahlhelm, that it's a touch too big for me - is there any way of replacing the liner? I can't see a way of adjusting it.
Atthefront have a good guide to how the german helmet sizing and liner sizing works:
http://www.atthefront.com/g_head_liners.htm
basically other than the string in the top to adjust how high it sits on your nugget, they are NOT adjustable in any other way! however you can "pad" the liner out a bit by placing felt, neoprene, cloth or something similar on the inside between the leather and the steel liner band which will tighten it up a fair bit, or you could wear a wool head-over toque which will keep you nice and warm and provide a bit of neck/ear/face protection from BB's
“I wanted to come to the Volga at a specific location at a specific city. By chance it carries the name of Stalin himself. So don’t think I marched there for this reason – it could carry another name – but because there is a very important goal... this goal I wanted to take – and you know – we are very modest, we have it already."
Adolf Hitler, November 1942
"Comrades, Red Army men, commanders and political workers, men and women guerrillas! It is on your perseverance, staunchness, fighting skill and readiness to discharge your duty to the country that the defeat of the German-fascist army and the liberation of the Soviet land from the Hitlerite invaders depend! We can and must clear the Soviet land of Hitlerite vermin."
Joseph Stalin, November 1942
I resized mine by using thin sheet foam in between the band and the leather as suggested, works a treat.
"I think we are in rats' alley - Where the dead men lost their bones."
Yep ! Gadge is right, that's the best way to reduce the liner size, and keep it comfortable. 
Cheers all, I try and get some of that and try it.
Hi guys,
Just happened to see this post, and thought i would let you know that my mate works in a leather goods shop, and on comission, can make new leather liners, using a supple leather and have it fitted for you.
The company is called 'clever with leather', and is located in brighton, wortha look guys 
Hang on! (x) of you, (y) of me, dont mind playing Airsoft, I make that Pimms O’clock