dfanonymous
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With the threading cut on the action as such, you wouldn't be able to order be fits next time to fit that action?
Thoughts from the pro's
- Thread starter Mainmechanic
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25WSM
Well-Known Member
Plus 1 on gcan. That is exactly the way it needs to be done. Everything needs to be 90 or straight to the race way.
Shep
Shep
Mainmechanic
Well-Known Member
Gentlemen thanks to all. I do agree with what everybody says about everything being square and concentric for the best odds of accuracy to quote Daveog. 25WSM , Gcan I agree completely. Susquatch appreciate you better being able to put my thought into words than I. Well done sir. Was wanting to stimulate thoughts. I would think recutting threads in action oversize would rule out prefit barrels per Dfanonymous question. Stated earlier not being a gunsmith. Grew up in my father's machine shop. He built or as he said "refined" who knows how many rifles and revolvers over the years. Very seldom replaced factory barrels , he always said their worse problem was not threaded and or chambered concentric. Basically did things similar to what I asked about along with rethreading and rechambering with good results. I can say there was occasions when he also had to recut action threads correctly to get the results he wanted. Stimulating conversation. Any more thoughts from anybody I'm still listening.
bigngreen
Well-Known Member
IMO work holding and set up tooling is critical to an excellent truing job, I don't think anything should be bases of the threads for set up, their function is to tighten a tenon to a shoulder, I've seen record holding 1000 yard BR guns with threads that are total wreckage, tight threads create more problems than loose ones also!!
The goal of a truing job is to hold the action stress free, find the center line of a warped action, square the surfaces the bolt and barrel seat on the action then take a crooked bolt and put it in the middle of that warped action under pressure. There is some influence from the firing pin, spring and how they are guided but that's another job. The barrel work takes care of the vast majority of the rest of it!
The goal of a truing job is to hold the action stress free, find the center line of a warped action, square the surfaces the bolt and barrel seat on the action then take a crooked bolt and put it in the middle of that warped action under pressure. There is some influence from the firing pin, spring and how they are guided but that's another job. The barrel work takes care of the vast majority of the rest of it!
I have done actions where I did not recut the threads larger but only using original barrels which are seldom class 3 threaded. Thats a whole other discussion.
I wouldn't "build" a gun on an OEM action and new barrel without recutting action threads.
As far as pre cut barrels go, you can buy a barrel threaded to any oversize thread. Its just a number. You can order a class 3a tenon thread to match your oversized 3b action thread. This would be covered in the term "Blueprinting".
When we re cut an action we produce a print of all the critical dimensions for that action.
An oversized action thread is usually cut using a +.010" 3a (male) go/no go gauge. Once cut, you can use that info to order a barrel. Unless you order a short chamber and finish ream for headspacing pre fit (chambered) barrels are a coin toss. However, theoretically Remington factory actions and barrels are cut to allow swaps but I'm a headspace snob and not a fan of pre-fit (chambers) barrels headspacing correctly. Never screw a barrel on to an action without gauges. Notwithstanding using a Remage/savage/Ruger system where u just use go/no go chamber gauges and tighten a barrel nut.
KyCarl
Well-Known Member
Why don't they Grind the threads? It's much closer than chasing on a lathe!
You can grind threads and bump the shoulder and get it Sq. with in .0001.
You can grind threads and bump the shoulder and get it Sq. with in .0001.
Yes you can. Its a longer and better process. I'm a toolmaker. Most gunsmiths could not afford, run or maintain a real thread grinder. Nice thing bout grinding threads is you never worry bout finish. However, if you're clever you can finish grind threads on a lathe. But that's all I'm saying bout that.
KyCarl
Well-Known Member
I know but a tool post grinder isn't as close? I mean grind them first class like the grinding on your Mic. spindles? Both sets ID and OD no backlash about a class 4?
Like grinding ID's on a lathe it works but I can do them better on the old Heald Red Head
ID grinder.
Like grinding ID's on a lathe it works but I can do them better on the old Heald Red Head
ID grinder.
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Thanks for clarifying. It is indeed a great topic for conversation & even debate. Maybe your dad is my generation and got some of his thinking from magazine articles that were our only source of info before such things as the internet, forums, and websites existed.....
I am an engineer and a machinist and I am obsessed with science and the question "Why?". I'm not satisfied just knowing something works, or "that's the way we always do it". That's why I liked your question so much and took the liberty of attempting to rephrase it.
It is my personal belief that accuracy is all about the fidelity of repeatability. In other words, if everything happens exactly the same every time, then the bullet should go through the same hole. If we hold the rifle exactly the same, pull the trigger exactly the same, the sear releases exactly the same, firing pin springs forward exactly the same hitting the primer exactly the same way, primer ignites exactly the same with the same timing and force, powder ignites and burns in a precisely repeatable progression, bullet and case are aligned to the bore exactly the same way and leap forward engaging the leade and accelerating forward down the barrel with exactly the same geometry and timing, the brass slides rearward engaging the bolt face and sealing off the chamber exactly the same with rifle recoil movement in our arms and rests exactly the same, and bullet exits the crown exactly the same, all given exactly the same bullet weight, geometry, and balance, and external conditions, then the result is one hole in the target.
Of course, many things conspire and collaborate to upset this beautiful progression of precise repetition. The goal is to build a perfect rifle, perfect loads, and perfect our shooting skills that all can constrain the differences that work against this repeatability.
With all that hot air behind me, I would like once more to focus on your question. Assuming that this theory and my understanding of it is correct, then why would concentric alignment of threads be more or less important than the alignment of the bolt raceway? If the theory is correct, then misalignment doesn't matter at all - provided that the misalignment is consistent and exactly repeatable, it shouldn't matter one iota!
Harold Vaugn's work on such things (see his book "Rifle Accuracy Facts") answered some of these questions but in the process raised more questions than answers. Building on his work, I think the answer to this question (if it can be answered) lies in the precision of these respective alignments and their contribution to overall repeatabity through stress in the components (hysteresis in the movements of the parts and their initial conditions before and after the shot) and the precision of the fit of mating components.
In my fragile mind, it does not take a huge leap of faith to see that its much better to use the raceway as a reference for all subsequent efforts to achieve precision than it is to use the threads simply because the raceway is longer than the thread length which results in better overall precision through a more precise reference for that work. Think of it a bit like using a 001 dial gauge to zero concentricity vs a 0001 gauge. The 0001 gauge is ten times finer than the 001 and the bolt raceway is roughly ten times longer than the length of the threads.
I think it's also fair to say that it's a lot easier to true the threads to the raceway than it is to true the raceway to the threads.....
Does it really matter? I don't think so. As long as either approach has the same final result in the precision of the fit and resulting stresses that affect repeatability, I don't think either one is any better or more important than the other in the end result. But the devil is in the details. Achieving equal precision is MUCH easier using the raceway so that's what most of us do.
That said, those old timers who used lapping compound instead of a lathe achieved good results despite themselves for the same reason. At that time it was much easier to improve precision by lapping to improve the fit than it was to use a lathe that had babbit bearings and crappy precision. In fact, I don't remember seeing any 0001 indicators back in those days! I do remember wobble wires though..... LOL!
As you can see, you touched a nerve with your question. Precision and repeatability are subjects I think about quite often when I am figuring out why a given rifle doesn't shoot to its potential..
Sorry to be so long winded. It's a major flaw in my neural networks. I do hope my thoughts help further yours.
Yes.
Grinding is for sure better. However most thread grinders are set up to grind between centers or full production models can work thru auto collets. They don't lend themselves to four jaw/spider sets. If you find a thread grinder that will accept 36" between centers it costs a phone number.
And if you have say a hardinge type tool lathe u can make a very nice thread grinder.
The thing bout barrels is we are not making gyros or shuttle parts or working to .00005". I know this is sacrilege but we are building guns. Point Cutting threads is fine.
There is a point where we are chasing accuracy to inflate prices. At some point enough is perfect.
Case in point.
This is a load test on a recent build for a nephew. 22-250. I did everything but action thread on his 700 sa because he had a new rem LV barrel. I set the chamber back a bit and rechambered with a manson reamer. Extended the factory tenon thread. Used a ptg .300 lug. Glass bedded it in an old HS Precision stock I had. While I know everything on the action was legit within a few thenths, the barrel and action threads were class 2 at best. Probably worse.
These groups were all shot off a bipod. Get a gun concentric and it will have low harmonics and shoot everything to same spot. The bottom right group was a load for another 22-250 we built. The question is simply, how much is enough? No shooter will ever out shoot or shoot better than this gun. And I would not call it a $$$$ build. So yes, we can chase tolerances to an extreme but unless you are shooting bench matches, and even then, the tolerances a lot of people tout are seldom realized or necessary. The trick is knowing where tolerance is critical.
KyCarl
Well-Known Member
I'm just trying to over think it? I've pulled a thousand broaches..Now they burn them faster and closer. Panagraph with fire and torches now Water? Cordax room to inspect in. I just want to try to get one as close as I can. using all the ISO stuff I had to learn.
Not to sell just to see if I can? The people where I retired from are Super Cool I can use a state of the art shop.. if I can't someone I know there can.
Not to sell just to see if I can? The people where I retired from are Super Cool I can use a state of the art shop.. if I can't someone I know there can.
Susquatch, I like the way you think. I am also an engineer by training, Aerospace to be exact, though I haven't used my training in many years. I got into rifle building, or as others have termed it probably more accurately, "gun plumbing," because I wasn't content buying a precision rifle. I wanted to understand why a precision rifle would cost $2,000-$3,000 more than an off-the-shelf rifle. So, I took machining classes, watched all of Greg Tannel's videos, bought lathes, and mills, and fixtures, and tools, and reamers, and gauges, and, and, and... I am convinced I've built some of the most expensive rifles in the world, and so is my wife! 
Not the best in the world, just the most expensive.
Anyway. Of all those rifles, the one I have kept over the years is the one I put the most effort into. On that particular rifle, I started with a stock Remington 700 short action receiver. I used a piloted raceway reamer to cut the raceway to a consistent diameter. I then recut the threads using the reamer, which was perfectly aligned with the raceway, as my datum for indication. Then I refaced the bolt lugs and receiver face. I then purchased a new single piece bolt from PTG to match the new raceway diameter and hand-fit it so there was just enough room to slide smoothly through the receiver, but not enough to allow unnecessary slop either. That bolt, despite being a precision made component, was also hand-lapped to mate perfectly to the receiver. I also machined a cut out to install a side bolt catch. Then, I purchased a brand new Bartlein barrel blank and indicted it in on the lathe using the bore as closely as humanly possible and proceeded to cut the tenon and chamber it slowly but surely. I put it all back together with a Timney trigger in a Manners stock and wouldn't you know it operated like butter and shot like expected.
So, all that to say, I now know why custom rifles cost as much as they do. If they're done right, the smith is putting a lot of time in the details. All the time and attention results in a rifle that will operate consistently shot after shot, and that's really were the precision comes from. Like you said, as long as the rifle and shooter do the exact same thing every time, the result should be consistent...as long as wind, and air, and etc. all do "their part."
I don't build rifles to make money, or to save money. I do it because I really enjoy seeing the results of a lot of careful effort. For me, that's the joy of it.
Not the best in the world, just the most expensive. Anyway. Of all those rifles, the one I have kept over the years is the one I put the most effort into. On that particular rifle, I started with a stock Remington 700 short action receiver. I used a piloted raceway reamer to cut the raceway to a consistent diameter. I then recut the threads using the reamer, which was perfectly aligned with the raceway, as my datum for indication. Then I refaced the bolt lugs and receiver face. I then purchased a new single piece bolt from PTG to match the new raceway diameter and hand-fit it so there was just enough room to slide smoothly through the receiver, but not enough to allow unnecessary slop either. That bolt, despite being a precision made component, was also hand-lapped to mate perfectly to the receiver. I also machined a cut out to install a side bolt catch. Then, I purchased a brand new Bartlein barrel blank and indicted it in on the lathe using the bore as closely as humanly possible and proceeded to cut the tenon and chamber it slowly but surely. I put it all back together with a Timney trigger in a Manners stock and wouldn't you know it operated like butter and shot like expected.
So, all that to say, I now know why custom rifles cost as much as they do. If they're done right, the smith is putting a lot of time in the details. All the time and attention results in a rifle that will operate consistently shot after shot, and that's really were the precision comes from. Like you said, as long as the rifle and shooter do the exact same thing every time, the result should be consistent...as long as wind, and air, and etc. all do "their part."
I don't build rifles to make money, or to save money. I do it because I really enjoy seeing the results of a lot of careful effort. For me, that's the joy of it.
Susquatch, I like the way you think. I am also an engineer by training, Aerospace to be exact, though I haven't used my training in many years. I got into rifle building, or as others have termed it probably more accurately, "gun plumbing," because I wasn't content buying a precision rifle. I wanted to understand why a precision rifle would cost $2,000-$3,000 more than an off-the-shelf rifle. So, I took machining classes, watched all of Greg Tannel's videos, bought lathes, and mills, and fixtures, and tools, and reamers, and gauges, and, and, and... I am convinced I've built some of the most expensive rifles in the world, and so is my wife!
Anyway. Of all those rifles, the one I have kept over the years is the one I put the most effort into. On that particular rifle, I started with a stock Remington 700 short action receiver. I used a piloted raceway reamer to cut the raceway to a consistent diameter. I then recut the threads using the reamer, which was perfectly aligned with the raceway, as my datum for indication. Then I refaced the bolt lugs and receiver face. I then purchased a new single piece bolt from PTG to match the new raceway diameter and hand-fit it so there was just enough room to slide smoothly through the receiver, but not enough to allow unnecessary slop either. That bolt, despite being a precision made component, was also hand-lapped to mate perfectly to the receiver. I also machined a cut out to install a side bolt catch. Then, I purchased a brand new Bartlein barrel blank and indicted it in on the lathe using the bore as closely as humanly possible and proceeded to cut the tenon and chamber it slowly but surely. I put it all back together with a Timney trigger in a Manners stock and wouldn't you know it operated like butter and shot like expected.
So, all that to say, I now know why custom rifles cost as much as they do. If they're done right, the smith is putting a lot of time in the details. All the time and attention results in a rifle that will operate consistently shot after shot, and that's really were the precision comes from. Like you said, as long as the rifle and shooter do the exact same thing every time, the result should be consistent...as long as wind, and air, and etc. all do "their part."
I don't build rifles to make money, or to save money. I do it because I really enjoy seeing the results of a lot of careful effort. For me, that's the joy of it.
Exactly. I chase tolerances as therapy not necessity. And I agree that the more things that are perfect the more likely we are to find perfection. While more to test ourselves, I'm just not sure all of it is necessary to create accurate rifles. Its is however necessary to create Art.
But you are right. If I machine (not a reamer kit) an action, bolt and barrel to min specs I have way toooo many hours invested to justify in every gun. So unless we all want to work for $10/hr, I understand why the guys who do this to an art form get the $$ they do. They are worth it. I'm fortunate. Like you, I own a machine shop for a hobby. I don't need to do anything for income, least of all something I love to do. That is the fastest way to turn love into stress.
Me too. The only differences are that I always wondered how they could be so cheap, and I build rifles for a huge army of friends, family, and the odd shooter that I take a liking to.
But I don't make money either. I'm too much of a perfectionist. When I die, I sure hope my wife doesn't sell all my stuff for what she thinks I paid for it.......
