Having trouble closing the action on my No4 Mk1*, need advise please.

[Bruce_in_Oz]

Peter is spot-on.

There is a caveat or two.

IF the bolt body and/or the action body is sufficiently "flogged out", the bolt-head will "float" up and down as it is cycled back and forth.

IF, furthermore, the bolt head lacks the tiny chamfers on the "rib", it is very likely that the guide-rail on the body will start to suffer chips rather quickly. I understand that this "chamfering" of bolt-head "ribs" started in Canada sometime in the late 1940's.

Another factor, closely tied in with the "looseness" of the bolt is the effect of a fully/mostly filled magazine has on the "tilt" of the "loose" bolt body. I have long harboured a suspicion that some of this damage can be sheeted home to "dry cycling" as there is almost ZERO vertical pressure applied to the bolt body by an empty magazine. Ditto the "style" of the operator's working of the bolt. Note that as you retract the bolt you are applying an upwards force on the bolt handle. This in turn depresses the front of the bolt. When that happens, the bolt head lug will rotate with the inner edge of that flat guide surface acting as a fulcrum. That MAY explain why the corner at the REAR of the gap seems to suffer the greater damage.

Or am I barking up the wrong tree here?