Re: Where do I find a used Rem700 SA for a good price?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 308nate</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: C. Dixon</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mmtuning</div><div class="ubbcode-body">Yea, truing an action is a little more involved than one thinks if the gunsmith does it correct. True bolt face, recut barrel threads on centerline, and sure up tenon seating area. </div></div>
It's been my experience that the bolt lugs and bolt face are pretty darn square from Remington out the door. This has been a reoccurring topic as of late. When one considers how the bolt is manufactured it's a simple operation that would be difficult to screw up. Near impossible actually.
The handle is almost certainly attached after the body of the bolt has been machined. Just makes sense from a manufacturing perspective to do it this way. That being said all were talking about is a facing operation on two surfaces. If there's going to be an error I'd suspect it's the distance from the back of the lug to the bolt face (or vise versa depending on how the print is calls out the dimensioning)
Fundamentally it's a pair of facing operations. The lug with a turning insert and the bolt face with a boring bar.
Either way the biggest error a machinist has to concern himself with is having a bad tool offset (be it from tool wear or a lazy setup) and goofing the distance between the two.
Where I'm going with this is an often underscored consideration when working on these actions, is the primary extraction (P.E.). <span style="font-style: italic">Any</span> machining on a lug surface, be it receiver or bolt, has a detrimental effect on the P.E. It's cascading as a number of other important design features become negatively altered as well. Fire control timing, striker fall, shroud timing, and P.E.
The only way to get it back is to reposition the bolt handle forward. Do that and now the back of the bolt has to be shortened to catch back up to the bolt handle. This means the cocking cam has to be pushed forward, the cocking piece detent needs machining, and now the shroud has to be remade because it won't time properly. Once that's done the cocking piece is now too far forward in relation to the trigger sear. The load bearing surface will also have to be altered to put things back into proper relation.
Very few gunsmiths pay this the attention it deserves. Opening the primary extraction also has a potential for elevated safety issues as now the gaps in the rear bridge are more exposed. In the event of a violent case rupture that gas will have better access to get to your face.
All of this should be considered when blueprinting an action and its often overlooked/ignored.
Now, back to the bolt lugs. When completed, the lapping process is the proof as to whether the puddin is any good. If the lugs are square with one another (in an unloaded state) the four surfaces should respond well to one another during lapping. If they clean up quickly (which in every case that I've done one in, they do) it means the bolt lugs were straight to begin with. The surface finish may have left to be something to be desired (not uncommon with a factory Remmy bolt) but the lugs are parallel and square to the receiver lug abutments.
Bottom line is lapping tells you if the process was done right and you get the benefit of improved lug surface finish just by the shear act of lapping them. (that's what it does)
This is why in my shop we only cut on the bolts as an absolute last resort. If they lap in quickly, we leave them alone.
Receiver threads are another matter. They are quite often out of alignment and machining them over does encourage the barrel tennon to run on the same center axis of the receiver. This is provided the tooling used in the lathe is set up properly and things like tool deflection are managed. One also has to ensure the threading insert is square to the thread being cut. If ignored you end up with a thread form that isn't accurate and this creates headaches when barreling.
Last is the distance from lug abutments to the receiver ring. The factory Rem distance is 1.150". Preserving this so the tennon dimensioning is maintained is something I feel is important. This is why I qualify all my tooling and have all my programing done in such a way to datum off the lug abutments. It's super easy to skim .005" off the lugs and then cut .01" off the receiver ring. You just altered the distance by .005". Not a show stopper, but I feel its better to keep it the same. The advantage I have is I can do both operations with a single tool which greatly reduces the chances of a shift in work offset or an error when switching from a boring bar to a turning tool on the lathe.
It can certainly be done, but it creates more work and the potential for an error is elevated.
Hope this helped explain some things.
C.
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All due respect, but I'm gonna disagree on this one.
I believe whatever you do, do not shorten your bolt when moving your handle forward, this would involve needing a longer cocking piece. If you keep the same cocking piece and just machine the catch back you reduce your firing pin throw which in turn reduces momentum to the primer thus has the potential to cause ignition problems. If you shortened the back of your bolt you would need to make a new cocking piece, a new shroud as well as re-machine the cocking ramp. You would have more into it than a custom action.
You can move the handle forward to set up proper primary extraction. This will only increase function, the only ill effect will be a cosmetic one, which is a greater gap from the back of the handle to the front of the shroud. If this bothers you, you can make a shroud that overhangs the bolt body. Even if you did have a very fine gap line, once your bolt is closed in the action some of the gap is back, depending on the thread pitch. Remington runs 13TPI which in a quarter turn equates to .019231, just under twenty thousandths. I believe it's the Alpine that run a fine thread, which would have much less movement in a quarter turn.
<span style="font-weight: bold">Was this part missed?</span>
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This means the cocking cam has to be pushed forward, the cocking piece detent needs machining, and now the shroud has to be remade because it won't time properly. Once that's done the cocking piece is now too far forward in relation to the trigger sear.</span>
Timing a bolt handle is more than just moving it forward, it is also a matter of clocking as well as many other angles to look at. I personally will take function over cosmetics. That said, I do not like to sacrifice cosmetics either.
Likes this?
LR, Inc. method for bolt handles
Here is how and why I do what I do when I am truing/timing an action.
First I insert a toolsteel truing mandrel with pilots into the receiver, then the receiver is placed in a 16C collet chuck which is fastened to a custom SSG back plate which has full angular and rotational adjustment. Next all of the angular ajustment is taken out of the receiver.Then the rotational run out is removed, then they are both double checked again, now the mandrel is removed. There is no stress on the action while machining therefore when the action is removed the machining is still true. Then the face of the receiver is remachined as well as the locking embuttments. The threads are then single cut true with the raceway. Now the receiver is removed, next I remove the bolt handle off the remington bolt.I then chuck the bolt body, get the bolt running true then single point remachine the bolt face and as Chad mentioned the bolts do usually run pretty true, but I feel the surface finish of the bolt face can be greatly improved upon. Therefore while everything is dialed in I re-machine the locking embuttments on the bolt to reduce lapping time.
After this the existing bolt handle or a new threaded bolt handle is attached by tig welding with emphesis on primary extraction.
Experience does not come quick or easy. There are so many angles to a bolt action rifle that many never realize, I am facinated by these things, so I eat and sleep them and hope to keep on aiming for perfection.
All this said, there are many ways to go about truing an action,I have trued actions many different ways over the years. I have come to this place mostly because it makes sense in my mind from a machinist stand point. Not that you are necessarily going to be seeing any more accuracy on the firing line than any other action truing processes, but I need to have confidence in my mind that what I am doing is making a difference.There are hundreds of accuracy minded gunsmiths here that are building awesome accurate rifles and I am not trying to take away from their talents. I do not believe I am beyond improvement and will keep striving to improve. I'm doing what I love and I love what I'm doing. I am all for the hobby guys that want to do their own work and would love to put some videos or books together at some point in the future that shares some of my learnings and why I do things the way I do.
308nate </div></div>