Kay..

SO now the main thing that is holding me back is a holster for Barry Burton.

I know what it is, a US army WII M6 shoulder holster.. but i can only find M3's.. which needs an extra strap adding to it...

Anyone can offer any help? Or advice?

I need to nail this right!

I've looked around several sites, can't find the M6 holster but based on the fact that Barry uses a colt I believe the M7 Tanker Holster will be a good option. I found a few of them on ebay and I have found several american website which sell them:

http://www.uswings.com/holsters.asp
http://www.pacificcanvasandleather.com/holsters/pcl_56_r.htm

or eBay:
http://www.ebay.co.uk/itm/U-S-M7-Colt-45-Leather-Shoulder-Holster-/281022467611?pt=UK_Collectables_Memorabila_RL&hash=item416e3e8e1b

http://www.ebay.co.uk/itm/U-S-WWII-COLT-45-M-7-SHOULDER-HOLSTER-BROWN-/120676097685?pt=LH_DefaultDomain_0&hash=item1c18db1e95

Hope that helps - sorry this isn't the one you mentioned in your post but from looking at gun enthusiast sites and other cosplayers I believe this is the closest available Also they all appear to have US stamped on them - the only way to not have that would be to commissions someone to make it. Good Luck

Heavily modified M7 is what I used for mine and the amazing alias.com modified it for me!

http://image.sportsmansguide.com/dimage/116692_ts.JPG?cell=200,200&cvt=jpeg

Looking at some pics this seems good