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Posted: 8/19/2014 9:19:07 PM EDT
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M48 mauser, only making contact on the top lug (the one w/ the ejector cut). Should i just lap it till the bottom lug makes contact, file the top lug down, get a new bolt? Edit: It's just an action no barrel yet. |
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Since no one else is giving you an answer, I'll kick it off.
I'm sure someone will be along in a minute with better advice. 
You might try a little gentle lapping, but be aware, you are opening headspace. If your rifle is on the loose end of the tolerance, you could easily end up with too much headspace; an out of spec rifle. You might get away with a couple thousandths. Might not. You would need a set of gauges to know where you are at. Lapping is usually done during/prior to barreling, the bolt is lapped in, then the headspace is set after. Fixes are : remove the barrel, lap the lugs in, set the barrel back one thread and ream to a good headspace. Surplus rifles were often assembled with miss matched parts by simply trying bolts until one was found that would headspace with the action. You could try a new bolt, but it would be a crapshoot that it would be an improvement. Finally, if you reload....You can lap until you have full contact, even if you are out of spec, then set your sizing die to just bump the shoulder on your " fireformed" cases, which will have stretched to the new, longer chamber dimensions, creating a mini-wildcat, as it were. But you must be very careful and know your business, continually resizing the cases to original size and firing them is a recipe for case failure, bad things can happen. In addition, it would be dangerous and unethical if the rifle could ever be sold or passed on in this condition, which would essentially in " No-go" headspace condition. Best bet: pull the barrel, lap lugs, set back barrel, recut the chamber. |
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A good source of info for things like this is the Jerry Kuhnhausen Shop Manual on the Mauser bolt action rifles.
It's available from Brownell's and goes into DEEP detail about subjects like this. One major "watch out" is that too much lapping will break through the very thin case hardened surface of the locking lug and ruin the bolt, if not the receiver. Kuhnhausen shows what that looks like with good pictures. He also goes into detail about what to do and what not to do if you have a lug that doesn't make contact. Much depends on how MUCH it's off. This is money WELL spent. |
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Quoted: Since no one else is giving you an answer, I'll kick it off. I'm sure someone will be along in a minute with better advice. You might try a little gentle lapping, but be aware, you are opening headspace. If your rifle is on the loose end of the tolerance, you could easily end up with too much headspace; an out of spec rifle. You might get away with a couple thousandths. Might not. You would need a set of gauges to know where you are at. Lapping is usually done during/prior to barreling, the bolt is lapped in, then the headspace is set after. Fixes are : remove the barrel, lap the lugs in, set the barrel back one thread and ream to a good headspace. Surplus rifles were often assembled with miss matched parts by simply trying bolts until one was found that would headspace with the action. You could try a new bolt, but it would be a crapshoot that it would be an improvement. Finally, if you reload....You can lap until you have full contact, even if you are out of spec, then set your sizing die to just bump the shoulder on your " fireformed" cases, which will have stretched to the new, longer chamber dimensions, creating a mini-wildcat, as it were. But you must be very careful and know your business, continually resizing the cases to original size and firing them is a recipe for case failure, bad things can happen. In addition, it would be dangerous and unethical if the rifle could ever be sold or passed on in this condition, which would essentially in " No-go" headspace condition. Best bet: pull the barrel, lap lugs, set back barrel, recut the chamber. Guess i should have mentioned that thre is no barrel on it so there is no headspace to worry about.
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Quoted:
Guess i should have mentioned that thre is no barrel on it so there is no headspace to worry about.
Quoted:
Quoted:
Since no one else is giving you an answer, I'll kick it off. I'm sure someone will be along in a minute with better advice.
You might try a little gentle lapping, but be aware, you are opening headspace. If your rifle is on the loose end of the tolerance, you could easily end up with too much headspace; an out of spec rifle. You might get away with a couple thousandths. Might not. You would need a set of gauges to know where you are at. Lapping is usually done during/prior to barreling, the bolt is lapped in, then the headspace is set after. Fixes are : remove the barrel, lap the lugs in, set the barrel back one thread and ream to a good headspace. Surplus rifles were often assembled with miss matched parts by simply trying bolts until one was found that would headspace with the action. You could try a new bolt, but it would be a crapshoot that it would be an improvement. Finally, if you reload....You can lap until you have full contact, even if you are out of spec, then set your sizing die to just bump the shoulder on your " fireformed" cases, which will have stretched to the new, longer chamber dimensions, creating a mini-wildcat, as it were. But you must be very careful and know your business, continually resizing the cases to original size and firing them is a recipe for case failure, bad things can happen. In addition, it would be dangerous and unethical if the rifle could ever be sold or passed on in this condition, which would essentially in " No-go" headspace condition. Best bet: pull the barrel, lap lugs, set back barrel, recut the chamber. Guess i should have mentioned that thre is no barrel on it so there is no headspace to worry about.
Useful information that is! Got one of These? My neighbor made me one that I used to lap the lugs, then clean up the bolt face. Here's a link to my Mauser Build thread , you can read my learning curve and all the good advice I received here, plus photo's of the tool my neighbor turned on his lathe for lapping the lugs and facing the bolt. |
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Quoted: The ONLY way I know of, hence, the tool. I suppose you can turn them to within a thousandth or so on the lathe if you could get it set up properly, but I would still lap it in. Are you getting at least partial contact on both lugs? Touching at some point?. It was only making contact with one lug.
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Take off barrels are a good source for lapping tools. Cut a case that fits the chamber in two pieces, put a strong spring inside, put the assembly into the barrel stub, screw it all into the action with the bolt already in place, and you're in business. The case head ought to fit the bolt face, and won't work if the case head is too large.
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Quoted:
Take off barrels are a good source for lapping tools. Cut a case that fits the chamber in two pieces, put a strong spring inside, put the assembly into the barrel stub, screw it all into the action with the bolt already in place, and you're in business. The case head ought to fit the bolt face, and won't work if the case head is too large. That's a good tip. Now I know what to do with at least one of the skinny 700 barrels I have. |
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Quoted:
That's a good tip. Now I know what to do with at least one of the skinny 700 barrels I have. Quoted:
Quoted:
Take off barrels are a good source for lapping tools. Cut a case that fits the chamber in two pieces, put a strong spring inside, put the assembly into the barrel stub, screw it all into the action with the bolt already in place, and you're in business. The case head ought to fit the bolt face, and won't work if the case head is too large. That's a good tip. Now I know what to do with at least one of the skinny 700 barrels I have. I started to make a universal tool, but I was in a hurry and the barrel I used was truly worthless for anything else. Hunting up two more barrels for a small and a magnum bolt head is probably worth while to save a little money, and someone working on guns constantly probably doesn't need to hunt for them. A take off stub could be reamed to a cylindrical "chamber", then a set of interchangeable mandrels made up for each bolt face, too. Better than buying the tools, if a person needs the experience and practice anyway. |
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Quoted:
I'll bet, Clover. Care to share what grits? Quoted:
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Clover comes in several grits, and it's not terribly aggressive. Want to guess what you'll get from the tool crib at the gunsmithing school at Trinidad JSC? I'll bet, Clover. Care to share what grits? I don't recall. The grit was sufficiently fine to polish and the rate of material removal was slow enough to control easily. Probably 600 or 800 grit. Clover is not only a grinding compound, it's used for polishing and lapping surfaces to achieve intimate fits. |
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I've used Clover. Even 320 grit is sufficient for this.
I prefer diamond paste only because it's generally held in a thicker compound that stays in the work area longer with less used, and in my opinion works faster relative to grit size. (Meaning 800 grit equivalent diamond paste cuts faster than 800 grit aluminum oxide or silicon carbide) but I don't have any data to support that. It's so inexpensive now, and comes in nice color coded syringes, and you can use it to lap your carbide lathe tools if you have the need as well. |
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