Ron J Posted March 25, 2009 Report Share Posted March 25, 2009 I'm pretty sure this has been gone over before, but here goes. Lets assume one has a commercial Mauser that has developed set-back. Touching up both faces on the barrel and re-chambering / re-heat treat would be the repair. But if it has iron sights and they are to be kept, can one complete revolution be removed safely? That seems like alot seeing as you lose one whole thread. Walnut Quote Link to comment Share on other sites More sharing options...
ken98k Posted March 25, 2009 Report Share Posted March 25, 2009 IMHO losing one thread would be okay. Depending on the barrel you may not lose anything. I've noticed on many mauser barrels the thread runs right up to the shoulder with no relief cut, whereas after market sporters seem to always have the last thread relieved. Quote Link to comment Share on other sites More sharing options...
Sailormilan2 Posted March 25, 2009 Report Share Posted March 25, 2009 I am sure I will get corrected if I am wrong, but I remember reading somewhere that it was safe to go down to about 3 1/2 threads. Losing one thread is not an issue. Or, it better not be, as I have done that to a couple of rifles that I own and shoot. Quote Link to comment Share on other sites More sharing options...
Vladymere Posted March 25, 2009 Report Share Posted March 25, 2009 There are two definitions of set back, I think, and believe you are mixing both in your question. You are asking if a barrel can be set back one thread to keep sights aligned in order to repair set back in a receiver. Yes, a barrel can be set back a full thread in order to keep iron sights properly aligned. In this instace the chamber is also recut to assure proper head space as setting back the barrel one thread results in a short chamber. Set back in a receiver is when the bolt locking lugs batter grooves into the receiver. If the grooves are very shallow you might be able to lap them out with out cutting through the surface hardening and into the softer receiver core. The usual fix for receiver set back is to replace the receiver. Vlad Quote Link to comment Share on other sites More sharing options...
sonic1 Posted March 25, 2009 Report Share Posted March 25, 2009 a barrel with 12tpi ...turned back one rev. will reduce headspace by .0833.... Quote Link to comment Share on other sites More sharing options...
tinkerfive Posted March 26, 2009 Report Share Posted March 26, 2009 Ron Just so long as you remember that even though you are setting back the barrel shoulders by 1 thread (.833") you will not necessarily be re-cutting the chamber .833 deeper to once again achieve proper head space. The restored proper head space will be deepened by .833 - ( the amount to true the lock lugs + any bolt face wear or truing + any original difference between minimum and actual). Assuming that the new primary and secondary shoulder crush = the original. I hope that was all perfectly clear. Tinker Quote Link to comment Share on other sites More sharing options...
Ron J Posted March 26, 2009 Author Report Share Posted March 26, 2009 I understand all of your explanations. The question was hypothetical. It doesn't concern the Peruvian I recently bought that shows set back. That one will be cleaned - recarburized and then a new barrel installed. (no need to realign anything or shorten thread tenon) I was wondering about something like my Higgins. I have not checked it for set-back or put head space gages in it yet. However, if it were in need of this and I wanted to salvage recvr and barrel with sights, then I see the only way as going the .083". I understand also that .083 may not be the final number - other factors will influence. I guess I could go approx 1/2 turn assuming reattaching the sights and restamping any numbers. Ron Quote Link to comment Share on other sites More sharing options...
z1r Posted March 26, 2009 Report Share Posted March 26, 2009 In the hypothetical higgins scenario I'd set the barrel back a turn to index the sights again at TDC. Then set headspace as required. I've done a ton like this. Most often due to barrel replacement or reuse on another rifle. Quote Link to comment Share on other sites More sharing options...
Ron J Posted March 27, 2009 Author Report Share Posted March 27, 2009 Can't beat this place - thanks guys. Ron Quote Link to comment Share on other sites More sharing options...
brian923 Posted August 2, 2009 Report Share Posted August 2, 2009 heres my question. if you take material off the lug surface of the reciever, and set it back, wont the bolt be to long? as you havent shortened the bolt? woundnt this create a gap between the rear of the lugs on the bolt and the front of the lug surface on the reciever? thanks, brian Quote Link to comment Share on other sites More sharing options...
Ron J Posted August 3, 2009 Author Report Share Posted August 3, 2009 Brian, I believe that while it is not a good thing to take material off these surfaces, I think the bolt would be okay. Seeing as how it is pulled onto those surfaces through the camming action, it wouldn't be loose. However, at some point you wouldn't be moving the cocking pc as far out of the rear of the bolt as normal and compressing the firing pin spring less. I also wouldn't want that area to be any thinner. As they say, the inherent strength of the Mauser is the design. The surface hardness provides wear resistance. (I feel the case hardness brings strength to the table, especially when done in todays modern gas carburizing furnaces, I'm no engineer.) Quote Link to comment Share on other sites More sharing options...
ken98k Posted August 4, 2009 Report Share Posted August 4, 2009 heres my question. if you take material off the lug surface of the reciever, and set it back, wont the bolt be to long? as you havent shortened the bolt? woundnt this create a gap between the rear of the lugs on the bolt and the front of the lug surface on the reciever? thanks, brian If you take any material off the recoil lugs I would definately have it re-heat treated. Quote Link to comment Share on other sites More sharing options...
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