Hi Mefidk. Nice looking old Arab gun. And, you have one with genuine British parts. Not only the lock, but the front lock screw, trigger guard (and rear sling swival), and ramrod appears to be from a M1853 Enfield. Can you post some additional photos? Especially the muzzle end and ramrod tip. Is the barrel rifled or smoothbore? I'm sure it just a coincidece, but the 98cm (39") barrel length is equal to the length of the M1853 Enfield rifle. But the standard Enfield rifle was a .577 caliber. However, the sharpshooter's rifle was about .45 caliber. From your photo, the front sight looks like it might be a filed down Enfield front sight? Again, more photos if you can. Thanks for posting!!! Wish I owned it.

Rick.