Since this subject comes up here from time to time, and almost daily in my work – I thought I’d document the steps typically taken to “True” a Remington action. Truing can mean different things to different folks depending on who’s doing the work and what level you are taking it to, but this is my take on what a basic truing job entails when someone employs us to do it. This may help some folks answer the age-old question of “Should I use a custom action, or a 700 donor?”
Step 1 – Evaluating the action. That’s right, there are some actions that aren’t worth your time. The thing to know is that almost all Remingtons are going to exhibit some level of warpage. Some more than others, but it’s always there(which is also why I’m not a fan of bedding blocks, mini chassis, etc for rem 700 applications).
This is not the end of the world and is just an artifact of the way they are manufactured. It only becomes a problem if it is severe enough that it hinders with locating the centerline of the action. This becomes immediately apparent when using the ground mandrel and precision bushings used to locate centerline. If the mandrel won’t slip through both bushings without using force, you just hit a red light. I’d punt on the project right there.
Assuming we made it through the first step, it’s on to the next go/no go evaluation. How far out are the receiver threads? It can almost always be “trued”, but at some point the juice may not be worth the squeeze. The worst one I’ve seen had .047” of runout. I’ll not do that again☹ Now we need to indicate the action in so we can see exactly what we are dealing with. I use a truebore alignment system fitted with a 6 jaw that lets me coaxially indicate without inducing stresses between the receiver ring and the rear bridge like most jigs or fixtures I have seen or used typically do.
Once we are dialed in on centerline I remove the mandrel and insert a threaded stub that has almost no runout. I have several of these in different thread sizes so we can get a before/after truing measurement. Basically the first mandrel lets us dial in to the action’s true centerline, and the threaded stub will follow the receiver threads to allow us to see/measure the runout in relation to centerline.
We will take a runout measurement right in front of the receiver face, and another about 3.5” out on the mandrel. We are looking for runout on 2 axis here. I refer to them “offset” and “deflection”. Offset which is measured just at the receiver face is referencing how centered the tenon is in the receiver itself. This has little impact on accuracy(within reason) and mostly affects how far off center your firing pin will strike the primer(assuming the firing pin is centered in the bolt bore. Lol).
Deflection is the real enemy here. It is the next measurement taken 3.5” downstream. This measurement determines how far from centerline your barrel is running out on the existing threads. Knowing these 2 measurements is critical and plays a big role in whether we want to proceed or take our 2nd opportunity to punt the project.
This is the point where the water can sometimes turn muddy, and also the point where a project has the potential to turn into a lot of wasted effort. We need to get real with our expectations, be honest about the limitations of what can/should be corrected and what the limitations of the tooling and action itself will allow.
There are several levels and steps of correction that can be applied here to yield an acceptable result depending on what those initial measurements looked like. I’ll run through some common scenarios.
Scenario 1 – Offset less than .005 and deflection less than .002 = do nothing with receiver threads and preserve standard tenon dimensions. This is actually pretty common on RR prefix actions believe it or not. The facing cut will only improve these numbers when we get to it later.
Scenario 2 - Offset less than .005 and deflection between .002 and .008 = Take a clean up pass on action face and cut tenon threads on new barrel to factory or prefit spec(loose) and still preserve standard tenon dimensions.
Scenario 3 – Offset greater than .005 and deflection greater than .008” = No getting around it, we’re boring the receiver .010 over and freshening up threads. This is the standard way most are treated from the beginning. I try not to go there unless it’s truly warranted. You end up with a ******* tenon dimension that could hinder future projects using pre-fits or remage systems, or trip up the next guy re-barreling it. But if you have to, you just have to.
Scenario 4 – Offset whatever and deflection between .008 and .015 = This is not ideal, but we’re still in the game if you really want to be there. We are boring .020 over and hitting the threads pretty good. You now have a super ******* tenon and really need to be mindful of that first scope base screw…..because the receiver ring just got a little thinner. LOL
Scenario 5 – Offset whatever and deflection greater than .015 = Can it be trued? YES. Is it worth it? My opinion is, no. I will usually call the customer at that point and let them make the call. Anything beyond this point I will punt! Haha
I mentioned realistic expectations and equipment limitations earlier. When it comes to receiver threads, you have to accept the possibility of a little runout when chasing threads. Holding .0005” or less is always the goal, but chasing existing threads can sometimes defy your best efforts. Single pointing a set of threads from scratch, or thread milling existing threads are the better options, but most shops aren’t going to offer thread milling. Mandrel guided tap systems are out there, but only follow the existing path. I have some and have tested them extensively, they live in a drawer collecting dust. Single point chasing existing threads is going to make up 99% of your options. By default your tool path will not be following a centered bore(or we wouldn’t need to correct it) so tool loading will be pretty uneven and tool flex will be a reality. It’s hard to predict or completely control runout in that situation down to the numbers we’re comfortable with in other operations.
Understanding all of that, and assuming our action met our initial requirements…………… Let’s true an action!
Step 1 – Evaluating the action. That’s right, there are some actions that aren’t worth your time. The thing to know is that almost all Remingtons are going to exhibit some level of warpage. Some more than others, but it’s always there(which is also why I’m not a fan of bedding blocks, mini chassis, etc for rem 700 applications).
This is not the end of the world and is just an artifact of the way they are manufactured. It only becomes a problem if it is severe enough that it hinders with locating the centerline of the action. This becomes immediately apparent when using the ground mandrel and precision bushings used to locate centerline. If the mandrel won’t slip through both bushings without using force, you just hit a red light. I’d punt on the project right there.
Assuming we made it through the first step, it’s on to the next go/no go evaluation. How far out are the receiver threads? It can almost always be “trued”, but at some point the juice may not be worth the squeeze. The worst one I’ve seen had .047” of runout. I’ll not do that again☹ Now we need to indicate the action in so we can see exactly what we are dealing with. I use a truebore alignment system fitted with a 6 jaw that lets me coaxially indicate without inducing stresses between the receiver ring and the rear bridge like most jigs or fixtures I have seen or used typically do.
Once we are dialed in on centerline I remove the mandrel and insert a threaded stub that has almost no runout. I have several of these in different thread sizes so we can get a before/after truing measurement. Basically the first mandrel lets us dial in to the action’s true centerline, and the threaded stub will follow the receiver threads to allow us to see/measure the runout in relation to centerline.
We will take a runout measurement right in front of the receiver face, and another about 3.5” out on the mandrel. We are looking for runout on 2 axis here. I refer to them “offset” and “deflection”. Offset which is measured just at the receiver face is referencing how centered the tenon is in the receiver itself. This has little impact on accuracy(within reason) and mostly affects how far off center your firing pin will strike the primer(assuming the firing pin is centered in the bolt bore. Lol).
Deflection is the real enemy here. It is the next measurement taken 3.5” downstream. This measurement determines how far from centerline your barrel is running out on the existing threads. Knowing these 2 measurements is critical and plays a big role in whether we want to proceed or take our 2nd opportunity to punt the project.
This is the point where the water can sometimes turn muddy, and also the point where a project has the potential to turn into a lot of wasted effort. We need to get real with our expectations, be honest about the limitations of what can/should be corrected and what the limitations of the tooling and action itself will allow.
There are several levels and steps of correction that can be applied here to yield an acceptable result depending on what those initial measurements looked like. I’ll run through some common scenarios.
Scenario 1 – Offset less than .005 and deflection less than .002 = do nothing with receiver threads and preserve standard tenon dimensions. This is actually pretty common on RR prefix actions believe it or not. The facing cut will only improve these numbers when we get to it later.
Scenario 2 - Offset less than .005 and deflection between .002 and .008 = Take a clean up pass on action face and cut tenon threads on new barrel to factory or prefit spec(loose) and still preserve standard tenon dimensions.
Scenario 3 – Offset greater than .005 and deflection greater than .008” = No getting around it, we’re boring the receiver .010 over and freshening up threads. This is the standard way most are treated from the beginning. I try not to go there unless it’s truly warranted. You end up with a ******* tenon dimension that could hinder future projects using pre-fits or remage systems, or trip up the next guy re-barreling it. But if you have to, you just have to.
Scenario 4 – Offset whatever and deflection between .008 and .015 = This is not ideal, but we’re still in the game if you really want to be there. We are boring .020 over and hitting the threads pretty good. You now have a super ******* tenon and really need to be mindful of that first scope base screw…..because the receiver ring just got a little thinner. LOL
Scenario 5 – Offset whatever and deflection greater than .015 = Can it be trued? YES. Is it worth it? My opinion is, no. I will usually call the customer at that point and let them make the call. Anything beyond this point I will punt! Haha
I mentioned realistic expectations and equipment limitations earlier. When it comes to receiver threads, you have to accept the possibility of a little runout when chasing threads. Holding .0005” or less is always the goal, but chasing existing threads can sometimes defy your best efforts. Single pointing a set of threads from scratch, or thread milling existing threads are the better options, but most shops aren’t going to offer thread milling. Mandrel guided tap systems are out there, but only follow the existing path. I have some and have tested them extensively, they live in a drawer collecting dust. Single point chasing existing threads is going to make up 99% of your options. By default your tool path will not be following a centered bore(or we wouldn’t need to correct it) so tool loading will be pretty uneven and tool flex will be a reality. It’s hard to predict or completely control runout in that situation down to the numbers we’re comfortable with in other operations.
Understanding all of that, and assuming our action met our initial requirements…………… Let’s true an action!
. You did some rebarrel work for my brother a few years ago. And he's been pretty solidly happy with it.
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