I ran a chamber reamer for 9mm into mine and fitted a block to the back of a P38 mag for a feed device. I had to lighten the slide inside but am not sure that was required. There was no outer mods done and it worked perfectly with ball and lead bullets...
Interestingly enough, C&Rsenal just did their newest video on this rifle. If you have time to view their content it is pretty good! Pop some popcorn and watch.
Winchester M1907 video:
“There are three kinds of men. The ones that learn by readin’. The few who learn by observation.
The rest of them have to pee on the electric fence for themselves.” - Will Rogers
My friend has a 1907 made in 1913 that was his grandfather's. He was a prison guard from when he came home after WWI until he retired in the late 50's and he took the Winchester with him. He passed in the late 60's and my friends mother put it away for him. He got it on his 18th birthday. It sat for another 24 years as it had no magazine or ammo. He asked me if it could be used so I checked it over cleaned and oiled it located 2 mags and ammo then we took it to the range. It did well all things considered and he's used it several times since.
Be aware there is a reason they called these things widow makers. Old timers had a bad habit of cocking these with the butt on the ground. If done improperly it went off and shot the guy. Don't be that guy! Only cock it on your shoulder and live a long life.
Early in WWI before they started mounting guns to planes French observers carried these with extended magazines. There are several reports of German planes being shot down with 1907's. - Bill
You forgot the smallest of the Winchester self-loading cartridges...the .22 Winchester Automatic cartridge for the M1903 .22 rifle. Still manufactured by Aguila and available by the 500 round brick.
These look quite similar to the standard .22 Long Rifle but come from the .22 Winchester Rimfire/.22 Winchester Magnum lineage of cartridges. The M1903 rifle was eventually manufactured in .22 LR as the Model 63 and survived into the 1960s....Taurus reproduced the M63 at some point so perhaps the M1903/M63 could be considered the most successful of Winchester's early self loader rifles