The picture and receivers belong to a friend that I consider a resource type on anything military. He is excellent on anything period correct, problem about being period correct had to do with how well 'it' works when finished.
For example: There are go-gages, no go-gages and field reject length gages. One day he finished a Rock Island 03 that was period correct for 1911; problem, the chamber was longer than a go-gage length chamber but shorter than a no go-gage chamber. The man has close to 25 30/06 chamber-gages, his collection includes the go-gage that measured off of the case body/shoulder juncture.
We have wasted a lot of time discussing grinding the back of the lugs etc. but for those that are listening he did not need a longer chamber and increasing the length of the chamber does not make the distance from the datum/shoulder to the bolt face shorter. Between us we have 135 06 and 03A3 bolts. I explained to him before we started we did not have a bolt that would decrease the length of the chamber by .0025".
What made my job Tuff/difficult when helping him? He was seeking help on the Internet.
Back to the 6 receivers; I have received some demerits for copyright infringements. Meaning I do not have permission to post the picture. I called him a few days ago to inform him a friend died, no problem but he did not know him. We had another friend die 'a while back', it seems when our age is added to the age of the 'old friend' and the total is divided by 2 the average comes out to be 80+.
30/40: There was the 30/06, before that there was the 30/03, before that was the 30/40 Us Gov. The rifle had a one lug bolt, it has been claimed a one lug bolt was all that was necessary. I believe the rifle would have had a two lug bolt if Springfield could have designed a rifle with a two lugged bolt.
F. Guffey