I saw a discussion between two friends today about firearms history. One said you couldn't easily acquire a military grade weapon pre-WWII back then due to cost and manufacturing ability. The other claimed that you could get a military grade weapon because the military was using the same level of tech available to civilians.
Which claim is true?
So, your friend is basically talking out of his rear end.
100 years ago puts us smack in the middle of US involvement in WWI. At that time, the US Army used two primary rifles, the bolt-action Springfield M1903 and the bolt-action M1917. The standard issue side arms were the Colt M1911 and the Colt M1917. The M1897 shotgun was also in inventory. All of these weapons were either available commercially, or had commercial equivalents that virtually replicated their performance. If anything, civilian weapons tended to be a bit nicer (in terms of fit and finish) than their military equivalents.
If you go back much beyond that - into the 19th century, say - you find a situation where the US Army's small arms tended to be rather old-fashioned compared to those in civilian use. The US Army didn't adopt a breech-loading rifle as standard issue until 1866; they had been somewhat common among hunters for more than ten years. The Army adopted the single-shot, blackpowder Trapdoor Springfield at the same time Winchester introduced the 15-shot 1873 Winchester.
This is to say nothing of the United States' long history of selling off surplus firearms to civilians, which has been going on since before the American Civil War and continues today in the form of the CMP. Prior to the Civil War, state purchasing agents bought up tens of thousands of old or broken muskets for pennies on the dollar, then used them to equip their troops after the war began. In the early 20th century, the government sold off tens of thousands of .45-70 Trapdoor Springfields, which soon became ubiquitous in country stores and hardware stores, often selling for as little as $1. And after WWI, the government sold off many, many 1903 and M1917 rifles to civilian shooters.
Now, certainly heavy weapons are and have been much more difficult to acquire for quite some time, but prior to the 1934 National Firearms Act it was mostly a matter of cost limiting demand. Up until that point, if you had $500, you could go down to your local hardware store and place an order for a fully automatic Thompson submachine gun.