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Old September 11, 2008, 03:15 PM   #1
ac700wildcat
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Lap m700 bolt lugs?

I picked up a new rem 700 sps stainless 25-06 last week. As I was home sick yesterday I decided to give it a good once over. I wanted to know how much contact the bolt lugs were actually making, so I put some magic marker on the back of the lugs and closed the bolt. I moved the handle just to the point that it was going to unlock about ten times and then removed it. I noticed that the one lug has virtually no contact and the other has a bit more, but really not very much.

Should I lap the lugs? If so, what is suitable for doing this? I know that if you go too far it can cause headspace problems, so I'm kinda hesitant. Any advice would be great.
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Old September 11, 2008, 11:58 PM   #2
44 AMP
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Shoot the gun first

Lapping the lugs to get them to bear evenly (and equally) is something yo don't need to worry about, until you have done alot of other things to your rifle and still don't get acceptable accuracy. If done incorrectly, it can, as you know cause serious problems.

Lapping the lugs/trueing up the action is something best done when building the rifle, before final headspacing. It can be done after, but if not done carefully, can cause you to need to have a lot of more work done.

You got a new rifle. Shoot it! Shoot it with different brands of ammo, different bullet weights. If you are into handloading, work up loads for it. Find out just how well the rifle (and you) can perform before you start tinkering with the gun. You just might find out that you don't need to!

Some folks will buy a new rifle, and then nearly completely rebuild it, (beacuse they like to), while others will spend time and money "improving" their rifle needlessly, simply because they didn't bother to find out what it was really capable of first.

Go out and shoot it a bunch, find out what it likes, and doesn't like. And then, if it isn't performing as well as you want, come back with details and we can suggest ways to go. Most rifles will out shoot most shooters, and spending money and effort for "improvements" that you cannot take advantage of is useless. I've seen people spend alot on "improvements" to get a rifle that will shoot 1/2 MOA or better, when the best they can shoot is twice that! Hearing them whine about how much they spent or how much work they had to do, and still the rifle will only shoot "xx" groups! Then when someone who can really shoot shows them what their rifle is capable of, you should see their faces!

Some people are naturaly fine shots. Most of the rest of us have to work at it, and some never get there. If you aren't there yet, you won't get much benefit from improving your rifle.
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Old September 12, 2008, 01:37 AM   #3
HiBC
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Here is another point of view.
There is always a little clearance around the bolt.When you evaluate the bearing of a locking lug by holding onto the bolt handle,you apply a load not truly in line.It can fool you.When I lap lugs,I use a tool I made that screws in like a barrel,and has a spring loaded plunger to appy force on the boltface.
If these surfaces are in the white,try a little cold blue,then just shoot it.See what that tells you.I will suggest lapping an assembled rifle might harm engagement.
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Old September 12, 2008, 01:55 AM   #4
HiBC
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Oops,its stainless! So much for cold blue!
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Old September 12, 2008, 01:42 PM   #5
ac700wildcat
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Thanks for the advice. I'll leave it alone and see how well I can get it to shoot. I shot it for the first time last night and ran 40 rounds through it between getting it sighted in and shooting a bunch of groups. My worst group was just over an inch and best was down to about 3/4" at 100yds. I'd say thats pretty darn good for factory ammo and a brand new rifle. Not to mention that I really disliked the targets that I had never shot at before.

I have everything I need to start developing a few loads for it, so I'll see how it shoots once I find a few loads with a low standard deviation when I shoot them over the chronograph.
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Old September 12, 2008, 01:56 PM   #6
brickeyee
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Quote:
Oops,its stainless! So much for cold blue!
Use Dychem or just a permanent marker.
They work on any metal.
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Old September 12, 2008, 06:43 PM   #7
Harry Bonar
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lugs

Sir;
Yes, it matters alot!
Yet, 80% of new rifles only bear on one lug and it is nothing but sloppy, unworkmanlike work!
It is said that all new rifles (and many, many surplus) only bear on one lug but that initial metal compression (set-back) will take care of this??
Well, would you like to know what the cause of inacuracy is? It's things like this and sloppy headspace!
You're trusting one lug to bear the total load of 53,000 copper units of pressure in your "new" rifle - this is unacceptable!
When looking at a rifle the very first thing I check is equal lug engagement!
This is why when we detail an action this is about the second thing we look at - the first being turned on a mandrel and facing off the front of the reciever ring slightly to get a perfect in-line barrel mount. Lugs can, and are, lapped very slightly but not enough to remove case hardening (such as in a Mauser) or in an alloy reciever like a Winchester, Remington or Savage, to name a few. But, after lapping the lugs you always adjust the headspace!
On a Remington, or any other "new" rifle to have to lap lugs is totally unacceptable!
Although I've seen many examples such as yours I would not own a rifle that had that condition. Modern 4140 steel properly heat treated will not compress enough to let that loose lug bear. Savage rifles are very good in this regard as the bolt head can "float" to some degree.
Harry B.
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Old September 12, 2008, 08:51 PM   #8
HiBC
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Agreed both lugs need to bear.
I am not saying both lugs will always bear in a new rifle,but we can probably assume a facing cut was made across both locking surfaces in the same setup the bolt body OD was cut.Likely an accurate bench inspection will show both lugs on the same plane.I have seen rough finish on lugs,knocking the high spots off is good.
I think in the mauser the lug recesses are part of a forging process,there may be more opportunity for trouble there.On a tubular reciever like the Rem,I'd expect the recesses have a good chance being machined right .Some heatreat warpage may occur.
I still say it is a real mistake to pull back on the bolt handle to check or lap the lugs.
Put a brass rod down the bore to push on the bolt face if you must,but only apply rotationalforce with the bolt handle.
I suspect you will find the locking lug in line with the root of the bolt handle shows the heavy bearing,but it ain't necessarily true if you are loading the bolt with the handle.
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Old September 12, 2008, 11:39 PM   #9
SRG
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Remington; $7 barrel, $15 receiver. That's about what it costs them to crank one out. Even the 40X. They don't spend a lot of time on these guns. If you get one out of the box that shoots worth a darn, you're lucky.
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Old September 13, 2008, 07:36 PM   #10
Harry Bonar
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lugs

Sir;
Now, how do we get around this? Well, you start with headspace guages. If (IF) the rifle just barely closes on the "GO" guage with no play, (ejector removed) then you may, if the lug isn't too far out lap the bearing lug until the other one touches (DO NOT LAP THE LOOSE LUG) and then run a "no-go" guage through the rifle. If (IF) the bolt will not close (DO NOT FORCE) then that rifle would considered to be within specification and you've done nothing wrong. The loose lug is only out probably maybe .003 (?) and the headspace allowable is usually .006 between the go and no-go guages.
While I decry such workmanship I do understand that in continuous use the loose lug will probably be brought to bear through use - but I decry this emphatically!
Mr. Kuhnhausens book is a very well written and accurate book on any subject and I would obtain one!

The common practice on Mauser if you are using the stock barrel is to correct headspace by setting it back a partial thread and correcting headspace - and - if a factory rifle is out badly the proper cure is to remove the barrel, detail the action and correct headspace by refitting the barrel which, of course, ruins the open sight alignment! The Remington action is homogeneously heat treated and lapping will not harm it, it's an alloy steel.
I'm sorry you have experienced this but thank goodness you are smart enought to make this check. Congrats!
Harry B.
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Old September 13, 2008, 09:52 PM   #11
James K
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Wow! So the first thing anyone should do with a new rifle, before firing even one round, is to spend $500 or so to have the bolt fitted, the action detailed and the barrel set back to adjust headspace. If this is not done, the rifle is complete junk and should be scrapped.

Sounds good to me. Just send me (shipping prepaid, of course) all those junk rifles; I promise to give them a good home. I might even shoot one or two, horrible as that idea might be.

Jim
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Old September 14, 2008, 04:02 PM   #12
Harry Bonar
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lugs

Jim;
I get you.
Harry B.
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Old September 14, 2008, 07:41 PM   #13
Harry Bonar
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lugs

Sirs;
I know that Jim is right that not one rifle has ever blown up due to lug engagement (He didn't say that but I'm just assuming). I do think that most clearances are so small that initial "set-back" will take care of this.
Still, I feel that headspace close to the no-go limit and sizing cases like the manuals tell you to (bump the shell holder against the die bottom) is A cause of poor accuracy. For the cartridge to be laying in the chamber of a rifle with .004 or .005 clearance and the clearance dimensionally in diameter is a very good recipe for innacuracy.
Now, I know some will disagree, but when I fit a barrel to an action I want it to just barely close on a "go" guage, or maybe set so that the cases I use experience a slight "feel" upon closing the bolt. This way I know that the datum line in the case neck is in contact with the chamber and bolt face.
This way the bullet is hopefully better aligned with the rifling throat (paralel or otherwise - a different subject) and gets a good start in life!
This gentleman is very astute to do the check he did and just not accept the factorys word that "this is a NEW rifle"!
With me, headspace and lug engagement tells me lots about a manufacturer.
More years ago than I care to recall I wrote Mr. Willian Ruger a personal letter pointing out misalignment in barrel and cylinder alignment - He kindly replied with a personally signed letter (which I proudly have to this day) and told me he would give it to the engineering department for correction.
Also, the belted magnum case is the most dangerous case we have today. We are slowly getting rid of belts on cases and I say Amen!
Harry B.
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Old September 22, 2008, 08:39 PM   #14
HiBC
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Interesting thoughts.
If you actually got a trace of lug bearing on the light contact lug,I think you have no problem. Get your micrometer out,wipe a little magic marker across it,let it dry,and decide how much clearance "only a light contact" means.
I don't think you are looking at more than .0002.
So now imagine you lap with 500 grit on the tight lug till you get lug contact.Surprise!!!The rocks in 500 grit are about .002.320 grit,about .003.Guess how much clearance you have when you clean it out?
Now,there is some diametral clearance around the bolt.Lets say .003 for fun.
When you touch the bolt handle,the bolt is deflected to the limits of this clearance.If both lugs were bearing equally,the force of your hand of the bolt would lift one lug off contact very slightly as the bolt deflects .0015

I'd say,shoot it!!
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Old September 26, 2008, 08:04 PM   #15
Daddy'sGirl
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winchester 52B

Could anyone on here be able to help? I am looking for a good replacement target trigger for a winchester 52B rifle and I am having no luck. Could someone tell me a good trigger and where I might be able to find one?
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Old September 28, 2008, 02:19 AM   #16
HiBC
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Daddy's Girl,
I think if you will start your own new thread about the trigger you will have better luck.Your question is a bit lost here lapping Reminton bolts.Good Luck
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