Safe to shoot this rifle?

[Woodsy]

As a gunsmith for over 50 years in a country where the .303 Lee-Enfield reigned supreme for a great many years, I can assure you that, subject to a headspace check, your rifle is perfectly safe to shoot. I have seen many rifles with pits inside and outside that were twice as deep as yours in everyday use with no safety problems. The BSA FTR '53 rifles were widely sold here in the 1960's and I got a new one for my 16th birthday in 1963. I sporterised it and fitted a scope and used it for hunting for several years including a spell as a professional culler and it accounted for 100's of deer, pigs, and goats before I upgraded to a .30-06.