I'm considering buying a Long Lee which has DP stamped on knox form and DP and EY on butt.I'm told they come from a regimental museum and were deactivated as display rifles by grinding down firing pin and blocking bolt head hole.New pin and bolt head fitted and just proofed.I've read the threads and warnings about DP markings but surely if just proofed its safe isn't it? I fully intend to shoot it regularly by the way.Any advice appreciated . Thanks