I have a 1903A3 Springfield and a friend of mine commented that they make a magazine conversion that replaces the bottom metal. I have never heard of it. Has anyone else or do they know where I can look at one?
There were 910 "Air Service" 1903 Springfields made during WWI. They featured a non-removable/fixed 25rnd magazine, shortened forend/handguard and modified sights. They were designed to be issued to pilots during the war who would not commonly be carrying ammo pouches, etc. They lightened the rifle by removing some of the stock materials and added a fixed 25 round mag so that the pilot, if downed, would have a sustainable rifle, with 25 rounds of ammo already loaded. I don't have a pic of one, but if you search for "Air Service 1903" or something similar, you should get a hit or two.
They are/were extremely RARE and never made it in to full production (mostly likely because the war ended before they could ever be fielded). To my knowledge, there are no aftermarket equivalent "conversions" for the 1903 rifles and frankly...if you "bubba" the rifle in such a way, someone will have to come to your house and beat the SH!T out of you with the butt of your rifle on sheer principle alone!!!
As ORD said there was a 25 round magazine version designed to be issued to US pilots during WWI but very few are still around. I haven't heard anything about a magazine conversion for the '03 and even if I had I wouldn't do it. I don't like to see vintage rifles or firearms altered from their original design.
There is one on display at the National Museum of the Air Force in their WW1 section. http://www.nationalmuseum.af.mil/
If I can find the pic, I'll post it.