Hello peeps, after talking with a very clever friend of mine he said if I had ever looked into the rifling marks left on the rifle/pistol heads. So, I got out a load of relics and had a look at the info I had to hand...
Grabbing a .45 head that I could clearly see had nice clear rifling marks, knowing that the US only really used these in Thompson's, Grease guns and the M1911 pistol. Luckily each of these has a different twist and number of grooves. So what I was now holding was certainly fired from a Thompson excellent.
Then came the dawnting task of looking at .303's and looking into how many guns used that caliber. So I made a list and nearly all the rifles have the same pattern, yet the Bren and Vickers are unique in there configuration... so a quick search through my heads and I found one fired from a Bren. (as most of you will know you can I'd Bren cartridge from the unique firing pin mark it leaves) I'm beginning to like Bren's more and more.
I have just compiled an excel spread sheet listing nearly all guns use during ww1 and ww2, there calibers, what was chambered, number of rifling grooves and which direction the twists go. If anyone wants a copy just ask. Or can I upload it somehow?