m-98 locking lug buttress ramps

[treeman]

I have a solid bottom98 mauser action made for benchrest. my question is , does any one know how the angles on the sides of the lug buttress going to the bolt ways are cut. the ones on a finished mauser appear to be flat. the ones on a savage action seem to be concave and cut in a spiral. I have asked several knowlegeable people here in OKC and none seem to have any ideas. maybe some one on this forum that has been in tool and die feild will have some ideas. I know the answer is not that difficult (110 year old tecnology)I'm just not that expierenced in machining proccess and haven't got a clue. thanks in advance for any ideas,
treeman

 

[Robert]

I have a solid bottom98 mauser action made for benchrest. my question is , does any one know how the angles on the sides of the lug buttress going to the bolt ways are cut. the ones on a finished mauser appear to be flat. the ones on a savage action seem to be concave and cut in a spiral. I have asked several knowlegeable people here in OKC and none seem to have any ideas. maybe some one on this forum that has been in tool and die feild will have some ideas. I know the answer is not that difficult (110 year old tecnology)I'm just not that expierenced in machining proccess and haven't got a clue. thanks in advance for any ideas,
treeman

Treeman,

The absence or replies semm to mean the subject is not an easy one, and I will try to rply the best I can:

Those ramps have two purposes :
-Clearing the necessary rearward movement of the primary extraction at the end of Bolt lift rotation.
-Ensure the transfer of the cocked firing pin on the trigger sear at the beginning of Bolt closure rotation. (I think you call that cock-on closing?).

As it seem to be for an unique model, those ramps are better made by trial and error, up to the moment the primary extraction allow closure. I think 40° angle would be OK for a 2-lugs design.
If you are handy with a file, make them that way for this prototype work……

I think if some model are cut concave, it is because they are cut with a end mill and the radius in question is those of the cutter.
There is no point in making those as an helix.

Ideal would be to have the ramps cut on both Bolt Lugs and Receiver Counter Lugs, this allowing the ramps width divided by two, increasing then accordingly the Lugs bearing area… but I see no other possibility to make the ramps in the Receiver counter lugs other than by electrode EDM??.

R.G.C