Is this part prone to breakage on the #4 Mk 1? I had to replace it on a recently purchased Maltby 1944 and found the part at Western Firearms in Australia for I think $4 US. I also purchased 2 #2 bolt heads that appear new and unused for $8 each. Also bought 100 Prvi Partizan .303B cases for $42US. Shipping was $16US. The brass is sold under the name Highland AX but it is Prvi brass with the Prvi headstamp. Very good brass! Prvi brass is supposed to be available soon from Graf & Sons.