Bolt heads No.4 Mk.1 LE.....

FY = Fazakerley. Mk. II = rectangular cocking piece, as opposed to the mushroom Mk. I.
There is an interesting style of headspace gauge for rimmed cartridges. Looks like a standard gauge, .064" for .303 GO, but there is a plunger centered in the gauge. It can move in and out. Close your bolt on the gauge, then measure the protrusion of the plunger. .064" + protrusion = the exact distance from breechface to boltface. Better than a GO, NO GO, FIELD system, because you get an exact measurement, not just a pass/fail reading. If the gauge rim were .060", you could measure a tighter than standard setup, which might be good for setting up a range rifle. I forget where I heard of this or who was making them. Really should make one up and see how it works.
 
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Thanks again! FY...Fazakerly eh? Why, then is there a Longbranch serial number on the bolt.....maybe another "put together" bolt? I am going to buy a headspace guage...enough of this guessing. Are the bolt heads that difficult to make that someone couldn't make a run of .010" oversized ones?
 
There is a market for overlength boltheads, but I suspect the cost of setting up and manufacturing them would be serious. Whether the demand would be great enough to justify the time and money is an open question.
What COULD be worthwhile would be to set up to alter existing heads. Build them up, remachine as necessary, heat treat. I'm not talking about doing them one at a time on a custom basis, but rather setting up and doing a batch. Could be on an exchange basis. Send in a head + $, get a remanufactured overlength one back. Could be cut to exact length.
 
tiriaq said:
There is a market for overlength boltheads, but I suspect the cost of setting up and manufacturing them would be serious. Whether the demand would be great enough to justify the time and money is an open question.
What COULD be worthwhile would be to set up to alter existing heads. Build them up, remachine as necessary, heat treat. I'm not talking about doing them one at a time on a custom basis, but rather setting up and doing a batch. Could be on an exchange basis. Send in a head + $, get a remanufactured overlength one back. Could be cut to exact length.
Click to expand...

What do you think of that welding and grinding process? Would that mess up the heat treatment to the point of making it unsafe?
 
The load is a compression one. I don't think it would be a problem. Build up the face, clean up the periphery, turn and grind the face, drill for the firing pin, re-heat treat. I think you would want to anneal after welding, before machining, then reharden.
Another method is to turn the face back, bore it out, silver braze in a new face with a shank going back through the head.
I have not personally done either of these modifications, but others have, successfully. The only modifications I've done to boltheads are rimfire conversion, and counterboring for .223 caseheads.
I have a number of boltheads to experiment on, and access to O/A and MIG welders. TIG might be the best way to go.
 
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