Recutting threads on a action, is it needed

[dtucker]

I am no gun smith by any means and was wondering about if having a action completely trued except having nothing done to the threads, does it have any impact on anything. I have a Tikka being built and is getting this treatment. I was told the walls are not thick enough to allow it to be done. It really does not bother me but just curious when i started thinking about it. I was kind of thinking that if the face was squared and the new barrel was being installed that the mating of the barrel to the face of the receiver would be the most important part. What if anything am i missing here?

 

[watercam]

It really depends upon your expectations. If you are looking for true benchrest accuracy (groups in the low 0.1"-ish at 100 yds.) then it may or may not make it. The Tikkas are pretty good actions to begin with. Stronger than Remmys with more horizontal support (more material covering the top of the action) and generally made to tighter tolerances. I think you can easily work up loads in the .2 moa range with a good barrel - I had a 595 with the same work you are having done and it was a terrific shooter out to 1000 yds.. Wish I still had it! Frankly if you want a true benchrest rifle you would be needing a benchrest (custom) action.

 

[Alex Wheeler]

In my opinion it will not make a difference if he cuts a loose thread. If the thread is too tight it will fight the barrel from mating to the shoulder freely. I feel like most gunsmiths cut too tight of a thread.

 

[CatShooter]

In my opinion it will not make a difference if he cuts a loose thread. If the thread is too tight it will fight the barrel from mating to the shoulder freely. I feel like most gunsmiths cut too tight of a thread.

They cannot cut the receiver threads too tight. When the receiver threads are cut, the threads get larger, not smaller. The barrel is cut and fitted to match the barrel threads.

With 120 foot pounds of torque on a barrel (which translates to ~2880 axial pounds of rotational force at the threads), the barrel is going to be tight into the shoulder of the action without any "fighting".

 

[jonbearman]

Cat shooter, do you tighten all receivers to 120 ft lbs? I have switch barrels and I don't tighten them that tight. Please advise.

 

[CatShooter]

Cat shooter, do you tighten all receivers to 120 ft lbs? I have switch barrels and I don't tighten them that tight. Please advise.

Yeah... I do not switch barrels. I do use an anti-seize on the threads.

 

[Alex Wheeler]

In my opinion it will not make a difference if he cuts a loose thread. If the thread is too tight it will fight the barrel from mating to the shoulder freely. I feel like most gunsmiths cut too tight of a thread.

They cannot cut the receiver threads too tight. When the receiver threads are cut, the threads get larger, not smaller. The barrel is cut and fitted to match the barrel threads.

With 120 foot pounds of torque on a barrel (which translates to ~2880 axial pounds of rotational force at the threads), the barrel is going to be tight into the shoulder of the action without any "fighting".

The threads I am talking about are the barrel threads, the action threads werent being cut, remember? Second, if your work is good theres no reason to torque a barrel anywhere near that tight.

 

[BoydAllen]

I have been told by a well known gunsmith that if you square the action face and cut your tenon threads to that they are on the loose side, that you should be fine. I apply a thin coat of Versachem anti-seize to the barrel threads, working it in with an acid flux brush so that it just colors the threads, with as little thickness as I can manage. I tighten by feel using a rear entry action wrench that only engages in the front receiver ring, with as much force as I can apply standing flat footed with my hands flush with the ends of the cross bar. If I had to guess, I would say that I am at under 100 ft lbs. I have never had an issue that I could trace to a barrel tightening problem.

 

[Northridge]

Hi dtucker, a very common question I receive from clients from time to time.

Its been my exsperiance that squaring the threads of a receiver does not define a builds success, but with out a doubt makes all other aspects of fitting a rifle to a higher standard possible. If I had to choose between square receiver threads or square front ring, I would choose the front ring. As others have said you can alter result of none true receiver threads with a "slightly loose" barrel tenon to allow abutments to come together with out inducing unwanted "stress" in my experience stress in a build is the devil!!! In situations where your using quality receivers, lathes capable of higher quality and and a human who can pull it off, you can fit to none drag gliding tolerances and have abutments engage with out adding stress. Indicating die is always used to verify contact points. As far as how tight to torque a barrel,I would agree in situations where all contact points are square to one another less torque is required. In situations where threads are tight and abutments are not square to one another it will require more torque, but as you are forcing the surfaces together you have just induced the devil "stress"

Long winded, but I hope this will be helpful and informative

Shawn williams

 

[expiper]

I usually torque to 50-60 ft lbs,,,,have did so many I go by feel ,,,Roger

 

[BoydAllen]

Just to be clear, the most accurate barrel that I have for my Viper actioned 6PPC has threads that are so loose that I did some measuring and calculating before installing and shooting it. The fit was my mistake. (story for another time) IMO machinists are prone to liking close fits, that may or may not relate to accuracy. A friend who learned to fit his own barrels once turned a handle too much which resulted in a disappointingly loose thread fit, after setting the barrel aside for some time, he decided to see how well it shot, thinking that he might at least get some value from it, fire forming cases To his surprise, it shot very well. Lest someone think that I am referring to some underachieving local, he has made the US WBC team at least twice. The smith that I referred to earlier is well known for building accurate 1,000 yard rifles, and has been for years. Frankly, I was somewhat doubtful when he told me, but given the difference in our experience, I thought that I should report what he had told me.

 

[carlsbad]

I am not in favor of recutting threads. I do not feel it improves accuracy and it makes your threads custom forever.

As for switching barrels, that is not as easy as unscrew one and screw on another so you already need a gunsmith help. But if the threads are all standard that makes the job a lot easier.

All my remington actions have stock threads. I won't buy a "trued" or "blueprinted" action for my personal use.

--Jerry

 

[JRS]

I am no gun smith by any means and was wondering about if having a action completely trued except having nothing done to the threads, does it have any impact on anything. I have a Tikka being built and is getting this treatment. I was told the walls are not thick enough to allow it to be done. It really does not bother me but just curious when i started thinking about it. I was kind of thinking that if the face was squared and the new barrel was being installed that the mating of the barrel to the face of the receiver would be the most important part. What if anything am i missing here?

Dan: go to the WTC (Warner Tool Company) website, and click on custom rifles at the top of the page. His explanations regarding the reasons are clear and easy to understand. Al Warner knows a little bit about building rifles 8)

 

[akajun]

In general, a slightly loose thread is better than a tight one, however what most people think of as tight or loose has to do with the minor and major diameter, and not the pitch diameter, which is what actually determines thread fit.
Lets say your working on a 5/8x24tpi thread. Common sense would tell you that your major diameter would be 5/8 or .625? right? Actually the fit for a class 2a thread calls for a major diameter of .6238 to .6166. or 7 thousandths difference.
however your pitch diameter, or the measurement of a datum line on the v of the threads, is .5976 to .5927 is 5 thousandths difference. This is measured with a thread mic or wires.
Now the reason that pitch diameter is more important than major diameter is that threads are self centering, as you draw the thread up, the v's of the thread push against each other and center up the parts. However if your major diameter is too large the threads can not center up as they are blocked by the crest of the thread . Now I'm not saying that having a barrel flopping around on the receiver is desirable, but I find it is better to give your threads some room to center up, and also prevents thread seizure and galling.
I think this explains why the loosely threaded barrels were able to still shoot very well.

 

[carlsbad]

Well said. I like the 3 wire method to measure thread pitch diameter. otherwise a thread mic is the way to go. I strongly agree with how important it is to NOT have your major diameter too large as this will make a loose thread feel tight and can result in a dangerously loose thread fit.

As for thread looseness, here are my thoughts:

A loose thread self centers since the thread shoulders are tapered. Thus the looseness won't affect the alignment of the chamber.

A loose thread engages less of the shoulder and can be slightly weaker with respect to pullout. Have you ever seen a barrel pull out of an action? The real time that a barrel thread needs to be as strong as possible is in the event of an overpressure event (plugged barrel) and generally the actions fail axially rather than the barrel pulling out.

I like to make things as good as possible so I tend to fit my threads pretty tight. But I also embed the threads and go by feel a lot. If a thread doesn't feel right I take another skim cut to loosen it up a bit.

--Jerry

In general, a slightly loose thread is better than a tight one, however what most people think of as tight or loose has to do with the minor and major diameter, and not the pitch diameter, which is what actually determines thread fit.
Lets say your working on a 5/8x24tpi thread. Common sense would tell you that your major diameter would be 5/8 or .625? right? Actually the fit for a class 2a thread calls for a major diameter of .6238 to .6166. or 7 thousandths difference.
however your pitch diameter, or the measurement of a datum line on the v of the threads, is .5976 to .5927 is 5 thousandths difference. This is measured with a thread mic or wires.
Now the reason that pitch diameter is more important than major diameter is that threads are self centering, as you draw the thread up, the v's of the thread push against each other and center up the parts. However if your major diameter is too large the threads can not center up as they are blocked by the crest of the thread . Now I'm not saying that having a barrel flopping around on the receiver is desirable, but I find it is better to give your threads some room to center up, and also prevents thread seizure and galling.
I think this explains why the loosely threaded barrels were able to still shoot very well.

 

[X Ring Accuracy]

In general, a slightly loose thread is better than a tight one, however what most people think of as tight or loose has to do with the minor and major diameter, and not the pitch diameter, which is what actually determines thread fit.
Lets say your working on a 5/8x24tpi thread. Common sense would tell you that your major diameter would be 5/8 or .625? right? Actually the fit for a class 2a thread calls for a major diameter of .6238 to .6166. or 7 thousandths difference.
however your pitch diameter, or the measurement of a datum line on the v of the threads, is .5976 to .5927 is 5 thousandths difference. This is measured with a thread mic or wires.
Now the reason that pitch diameter is more important than major diameter is that threads are self centering, as you draw the thread up, the v's of the thread push against each other and center up the parts. However if your major diameter is too large the threads can not center up as they are blocked by the crest of the thread . Now I'm not saying that having a barrel flopping around on the receiver is desirable, but I find it is better to give your threads some room to center up, and also prevents thread seizure and galling.
I think this explains why the loosely threaded barrels were able to still shoot very well.

Well put

 

[Roeder]

I am no gun smith by any means and was wondering about if having a action completely trued except having nothing done to the threads, does it have any impact on anything. I have a Tikka being built and is getting this treatment. I was told the walls are not thick enough to allow it to be done. It really does not bother me but just curious when i started thinking about it. I was kind of thinking that if the face was squared and the new barrel was being installed that the mating of the barrel to the face of the receiver would be the most important part. What if anything am i missing here?

Getting back to your question... It really depends on how straight the original threads are. I have never worked on a Tikka. I have seen some Remington receivers with threads significantly out of concentricity and misaligned as well. I have also seen some that were so straight that a very light cut cleaned them up when the receiver was dialed true to the bolt bore. Some years ago the standard gunsmith accuracy work rarely involved re cutting the threads, now many smiths do it to all of them. If the factory threads are reasonably straight and the new barrel is fitted with a reasonable amount of clearance it should be fine.

 

[Eddie Harren]

"I torque all of my barrels to 120 Ft/Lbs." Only if the chamber is polished to a mirror finish as well, right Cat?

 

[BoydAllen]

(Off topic) A little gunsmithing tip:
A friend, who builds very accurate rifles, and loves to push magnums to their accurate limits, told me that after he has installed a barrel for the first time, at full torque, he will use the reamer, extension, and T handle and run the reamer back in the chamber to recut the constriction that happens under the action threads from V threads being tightened. He then removes the barrel, does a little polishing of the chamber, and reinstalls it. This is primarily an issue for chambers that have large diameter bodies (thinner chamber walls) that are longer than the action's threads. He has also found that chambers that are smaller in the back, get to a tight bolt sooner than if they are slightly larger. He has two reamers that are for wildcats based on the WSM case, one a .25 and the newest a 6.5. When he was working up loads for the 6.5 he ran into a situation where he was at an accuracy node, the primers and other signs that might indicate pressure were OK but there was more drag on the bolt than he likes. He had not had that show up in the same way with the .25 caliber version, so on the chance that there might be a difference in dimensions , he ran the .25 cal. reamer in the 6.5 chamber, and found that it removed some metal at the back of the chamber. He then polished the chamber lightly, and retested. The problems was gone. One reamer is just a little bigger than the other, even though they were built to the same body dimensions, by the same manufacturer.

 

[X Ring Accuracy]

Makes sense actually. Thanks for the tip