Enfield No.4 Hairline Cracks

[Surpmil]

Well I suppose I'll go first then: 'wouldn't worry about the crack that probably runs more or less vertically through the back of the forend as the strap will prevent that going any further horizontally and vertical spreading would be pretty unlikely once the forend is sandwiched between the guard and the bottom of the receiver.

The crack on the lower right is a different matter, and that one should/could be drilled and dowelled from inside the slot the guard sits in.

Am not aware of any glue that works on oily wood, albeit a vegetable oil, but there may be something others know of. So, do you want to get into the finish removal that cleaning the oil out/off would require? If not, drill the holes, use a strong dowel (I'd use bamboo myself, from chopsticks), some epoxy and call it good.

There's one take on it and you will no doubt receive others!