I believe all #1's were Black powder and #5's were smokeless.
What caliber is it?
How do I tell???
Re: How do I tell???
All the No 1's were for large black powder cartridges. The exceptions would be the M 1896 and M 1897 smokeless powder rifle and carbines chambered for smaller smokeless powder cartridges. These are most commonly found in 7mm Mauser caliber. Yours is a Mexican contract so, if you can't put your little finger in the bore then it was originally chambered for the 7mm Mauser. The M 1896 and M 1897's used left over black powder receivers that were hardened for smokeless pressures. Have a gunsmith check your rifle. If it is not too abused then it should be OK for starting load 7mm Mauser pressures. Be advised though, the 7mm Mauser cartridge, when standardized in the USA under SAAMI, took on a very slightly shorter length between the base of the case and the shoulder. This results in a slight headspace problem with 7mm Rolling Blocks (and probably any other older 7mm Mauser-chambered rifle). This can be remedied through some reloading tricks that have been covered here before.
Re: How do I tell???
If you are interested in Military Rolling Blocks, get a copy of George Layman's book: "The All New Collector's Guide to Remington Rolling Block Military Rifles of the World". He also covers foreign contracts.