I'm curious how anyone does this at home, what if any special tools might be needed. What grit you use etc.
corelokt308win
There is no big mystery to lapping lugs, one just needs to use a little caution as to not affect the headspace of a rifle that is already barreled.
More often than not, a new out of the box rifle will only have contact on one of the locking lugs.
Most Receivers are lapped prior to being barreled or re-barreled and not after the barrel has been installed.
All you are doing is removing metal little by little to increase contact between the action and the bolt locking lugs.
50 to 60 percent contact on all the lugs of the bolt is common, any more than this is up to the individual but really provides no more additional benefit.
This can be done without any specialized tools in regards to a specific brand of firearm.
You will need some lapping compound ( i.e. clover oil based lapping compound ), a parts washer is handy but not required,
some kind of solvent to clean out the lapping compound in between checking surface contact, a marking method, ( I have used a black marker for a great many years ) and a little patience.
First, remove the extractor and ejector from the bolt if possible.
Leave the firing pin assembly in place on the bolt, ( you will utilize the tension of the spring for lapping ).
Have the trigger assembly installed on the action as well, this will contact the cocking piece on the bolt and provide the spring tension )
Mark the contact surfaces of the bolt lugs with your marking solution and insert the bolt into the receiver as far into the receiver as it will go, while still applying pressure forward on the bolt handle turn the bolt in the proper direction to close it, release forward pressure.
By keeping pressure on the bolt handle it will minimize dragging of the bolt lugs on the mating receiver surfaces and provide a more accurate representation of the actual existing contact.
With the bolt in the closed position, rotate the bolt handle about half the distance necessary to unlock it and then rotate it back into the closed position, do not let the bolt disengage the locking lugs as this will give you a false reading as to how much contact you have.
Do this about ten times and then, with forward pressure, unlock the bolt and extract it from the receiver to see how much contact you have.
Once you know where you stand, apply some lapping compound sparingly to the locking lugs on the bolt and insert as before with pressure forward and then close.
Under spring tension, rotate the bolt as described before, unlock about half the distance and then closed again.
Perform this anywhere from 40 to 100 times, then as before with forward pressure, unlock the bolt, remove it from the receiver and utilizing your solvent clean off all the lapping compound from the bolt and from inside the receiver.
Mark the lugs and repeat the process for checking contact.
Repeat the lapping process as necessary to obtain the desired results.
If this is being done to a rifle that already has a barrel installed, check with headspace gauges intermittently during the operation to make sure that you have not created excessive headspace by lapping the lugs.
**If for some wild reason you feel compelled to lap the lugs on a Weatherby Mark 5……the best I have ever seen obtained is having 6 of the 9 lugs contact ( this operation on a Weatherby was considered ludicrous by all the members in the shop though, but the customer got what he wanted and paid for it handsomely )
“Clover” comes in several grits, you may want to stick with about 800 grit when first starting out.
If you find that you want to exert more caution in this process you could use an even finer grit like 1000.
Unfortunately this written explanation is rather long, the method is simple and to show someone how to do this would take about 5 minutes, so sorry for the lengthy reply.
More often than not, a new out of the box rifle will only have contact on one of the locking lugs.
Most Receivers are lapped prior to being barreled or re-barreled and not after the barrel has been installed.
All you are doing is removing metal little by little to increase contact between the action and the bolt locking lugs.
50 to 60 percent contact on all the lugs of the bolt is common, any more than this is up to the individual but really provides no more additional benefit.
This can be done without any specialized tools in regards to a specific brand of firearm.
You will need some lapping compound ( i.e. clover oil based lapping compound ), a parts washer is handy but not required,
some kind of solvent to clean out the lapping compound in between checking surface contact, a marking method, ( I have used a black marker for a great many years ) and a little patience.
First, remove the extractor and ejector from the bolt if possible.
Leave the firing pin assembly in place on the bolt, ( you will utilize the tension of the spring for lapping ).
Have the trigger assembly installed on the action as well, this will contact the cocking piece on the bolt and provide the spring tension )
Mark the contact surfaces of the bolt lugs with your marking solution and insert the bolt into the receiver as far into the receiver as it will go, while still applying pressure forward on the bolt handle turn the bolt in the proper direction to close it, release forward pressure.
By keeping pressure on the bolt handle it will minimize dragging of the bolt lugs on the mating receiver surfaces and provide a more accurate representation of the actual existing contact.
With the bolt in the closed position, rotate the bolt handle about half the distance necessary to unlock it and then rotate it back into the closed position, do not let the bolt disengage the locking lugs as this will give you a false reading as to how much contact you have.
Do this about ten times and then, with forward pressure, unlock the bolt and extract it from the receiver to see how much contact you have.
Once you know where you stand, apply some lapping compound sparingly to the locking lugs on the bolt and insert as before with pressure forward and then close.
Under spring tension, rotate the bolt as described before, unlock about half the distance and then closed again.
Perform this anywhere from 40 to 100 times, then as before with forward pressure, unlock the bolt, remove it from the receiver and utilizing your solvent clean off all the lapping compound from the bolt and from inside the receiver.
Mark the lugs and repeat the process for checking contact.
Repeat the lapping process as necessary to obtain the desired results.
If this is being done to a rifle that already has a barrel installed, check with headspace gauges intermittently during the operation to make sure that you have not created excessive headspace by lapping the lugs.
**If for some wild reason you feel compelled to lap the lugs on a Weatherby Mark 5……the best I have ever seen obtained is having 6 of the 9 lugs contact ( this operation on a Weatherby was considered ludicrous by all the members in the shop though, but the customer got what he wanted and paid for it handsomely )
“Clover” comes in several grits, you may want to stick with about 800 grit when first starting out.
If you find that you want to exert more caution in this process you could use an even finer grit like 1000.
Unfortunately this written explanation is rather long, the method is simple and to show someone how to do this would take about 5 minutes, so sorry for the lengthy reply.
Good explanation. I did once lap the lugs on my M70 with some of the Rem-Oil that has abrasive in it.... took a while, though.
Didn't go for 100% contact as I didn't want to change headspace, but got most of each lug in contact.
You can cold-blue the backs of the lugs to make it easier to see progress.
Didn't go for 100% contact as I didn't want to change headspace, but got most of each lug in contact.
You can cold-blue the backs of the lugs to make it easier to see progress.
Lapping lugs...1st step to amazing accuracy for me. Just maintain attention to detail and clean thoroughly after lapping. Test often and keep records for future reference.
I did this on my new mod 70 300 h&h several years ago (1993). One lug had <10% contact, the other about 30%. When I was done I had 90-100% both lugs. It brought my groups from 2+" down to 1.25-1.5".
Then came the pillar/glass bedding of action (done by myself w/ instructions from an article by Ross Seyfried) and a trigger job. (I left the trigger to an accomplished gunsmith) Barrel was free floated to see how it would shoot. Its still free floated, as I am afraid if it was glassbedded it might change for the worse.
WOW!!! What a shooter now. I shot my first cloverleaf. (IMR4831 and a Sierra Matchking)
I did this on my new mod 70 300 h&h several years ago (1993). One lug had <10% contact, the other about 30%. When I was done I had 90-100% both lugs. It brought my groups from 2+" down to 1.25-1.5".
Then came the pillar/glass bedding of action (done by myself w/ instructions from an article by Ross Seyfried) and a trigger job. (I left the trigger to an accomplished gunsmith) Barrel was free floated to see how it would shoot. Its still free floated, as I am afraid if it was glassbedded it might change for the worse.
WOW!!! What a shooter now. I shot my first cloverleaf. (IMR4831 and a Sierra Matchking)
Is a lot easier to do with just a bare action in hand...but most of us are re-working factory assembled rifles and not willing or able to remove the barrel.
Just remember to (1) not go too far (2) keep that lapping compound off of other surfaces.
Can list all the bad things that can happen if the job goes wrong, but usually you can keep yourself out of troube by LOTS of stopping, cleaning off, and checking. Will spend the better part of a day cleaning things off...measureing and checking with "spotting" (removal of color as you check the fit)...just to get it gritty again for a few more stokes.
Fopr spotting, can use cold blue....but on some stainless\, cold blue won't take. Can just simple Marks-A-Lot so long as the parts or dead clean and oil free.
Just remember to (1) not go too far (2) keep that lapping compound off of other surfaces.
Can list all the bad things that can happen if the job goes wrong, but usually you can keep yourself out of troube by LOTS of stopping, cleaning off, and checking. Will spend the better part of a day cleaning things off...measureing and checking with "spotting" (removal of color as you check the fit)...just to get it gritty again for a few more stokes.
Fopr spotting, can use cold blue....but on some stainless\, cold blue won't take. Can just simple Marks-A-Lot so long as the parts or dead clean and oil free.
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