Gunsmithing Teflon tape in barrel/action joint?

[gunnergirl81]

Been looking for a S/A donor action, and stopped in a small gunshop to see if they had anything. There was an obviously semi custom R700 on the rack with a heavy SS barrel and the tag said it was a Hart. I pulled the bolt and while looking at the chamber/lug recess area noted that there was teflon tape showing around the edeges.

I thanked the shop owner and left. When I asked my husband about it he said it happens!?! Really? He even said some research showed it resulted in better contact between the barrel and receiver threads. Was this a common practice? I was sure some hackery was afoot, but Jim said it was something that folks with pre-threaded barrels did when there was slop in the threads and its been shown to hold up better than locktite as the locktite breaks down from the heat/shock of repeated firing.

Is this true? Is it safe? Just wondering, I'm still learning and he was busy all weekend catching up on a large backlog of work so teaching wasn't a big priority.

 

[jacq220]

Re: Teflon tape in barrel/action joint?

I have heard of savage people using it to help tighten things up a bit, but none of those people ever seemed to have before AND after data.

seems hokey to me also, but for a prethreaded barrel where you dont have any control over the fit of the threads then it seems like it may be an OK fix.

 

[SScott]

Re: Teflon tape in barrel/action joint?

You may have stumbled onto the new tacticool "Mod" making you barrel water tight for shooting in adverse weather conditions. LOL
It sounds more like a band aid for a poor fit up.
SScott

 

[LRI]

Re: Teflon tape in barrel/action joint?

On a barrel I'd avoid.

However. . .

A guy I chat with often is a BR fanatic out in Sacramento.

He had two identical actions, Stolle Pandas chambered in the same cartridge. One shoots exceptionally well, the other was mediocre. When he switched barrels the "bad" gun didn't get any better. He went through a process of elmination one part at a time.

Oddly enough, when he switched bolts it did improve. Chipping away at this further he determined the root of the cause lied at the thread fit between the bolt and shroud.

Wrapping the shroud on the "bad" gun with teflon tape seemed to improve performance.

Now, normally I'd wrinkle my nose at this a bit and just go on with my life. However, back when I worked for Nesika Glen Harris was working on the Model 10 action. It was a prototype receiver design that paid very close attention to the fire control fit. My reasoning for bringing this up is apparently Glen felt there was something to it also.

I wouldn't go out on a limb and start advocating everyone wrap up shrouds with tape as it's a cheesy fix imho. But I do make my fire controls for Remingtons with very close attention paid to how the two parts screw together. thus far they seem to work.


Not a direct answer to the question and I apologize for derailing it a bit, however its 'sorta' related so what the hell.

Hope this helped.

C.

 

[doc76251]

Re: Teflon tape in barrel/action joint?

If there is room for Teflon tape in a barrel/receiver match up I would question everything else the gun plumber that did that job ever touched.

Cheers,

Doc

 

[gunnergirl81]

Re: Teflon tape in barrel/action joint?

It seems like a very "bandaid" type application if used to compensate for loose threads. Not necesarily complete hackery, but far from the more involved right way to do things.

I've been googling it and suprisingly what few references seem to indicate no harmful issues with its use. They cite Harold Vaughn and his research and discuss more about the ability of the barrel to be torqued to a higher spec with the teflon tape acting as a lubricant. This resulted in a better mate between the barrel and receiver threads and less movement/flex in the joint.

Now I'm wondering if the barrel I saw used the tape to make up for loose tolerances, or if the builder was following along the path made by Vaughn.

 

[SDWhirlwind]

Re: Teflon tape in barrel/action joint?

An oldtimer gunsmith that lived just west of here had some real good fixes. He had lost an eye from a 99 in 300 Sav some years back and his left eye wasn't real good anymore. His ability to grind lathe bits etc wasn't good in part from eyesight and in part that he wasn't a perfection fanatic.

He was a huge mauser fan and had an old I think 9" SB and did everything on center. He always cut 60* threads for the 55* mauser actions. You honestly couldn't wipe his threads off with a paper towel because they were so damn narly and usually undersized. His fix when done chambering, smear marine resin on the barrel threads and release agent in the reciever and screw it together for his 'perfect' fit.lol I ended up with a Shilen he had taken off that "wouldn't shoot" that he put on a Sako in 222mag, it had expoxy on the threads. Just a few years ago a friend brought over a 222mag in a 722 that the gent had rebarreled yrs ago and he was having problems chambering reloads. Chamber was about .004 short on a go guage and the narly damn threads on the threaded shank measured 1.029". Got alot of room that way to make shitty threads fit the reciever I guess.

Guess if you are creative enough and have the ability to BS your customers then near anything goes. A few people that know absolutely nothing about building a rifle still admire his work and pay premium prices for a gun built by him if one comes up for sale! He always bedded them with Marine epoxy because "it was cheaper" than Acraglass.

 

[turbo54]

Re: Teflon tape in barrel/action joint?

I'm gonna play devils advocate for a moment...

First off, let me state for the record that it just seems like intuitive common sense that a sweet, class AA thread fit between tennon and receiver is "correct".

However.....why?

The way I see it, the barrel/receiver joint needs to achieve 2 main functions:

1. Provide a sufficient clampload between barrel and receiver, to minimize deflections, and stop them from coming apart.

2. Locate the barrel, so that it is coaxial to the bolt centerline and bolt raceway.

The second point really has two subpoints...

1. Obviously, the shoulder on the barrel tennon needs to be square to the bore axis. Provided the face of the receiver is also square to the bolt centerline/bolt raceway, the shoulder on the tennon will butt against the receiver face, thus ensuring the bore axis is at least PARALLEL to the bolt axis.

2. A sweet, class AA threadfit between tennon and receiver will keep the bore axis centerline concentric to the bolt centerline/bolt raceways.

However, lets say you only achieve a class B threadfit, so there is some wobble/play between tennon and receiver... As the tennon shoulder butts against the receiver, won't the 60º threadform angle self-center the barrel to the receiver, thus providing the required receiver/barrel concentricity?

 

[Straight Shooter]

Re: Teflon tape in barrel/action joint?

As a neversieze a small amount I doubt it hurts anything. Seems very harmless compared to the concoction of goo that Remington is glueing their barrels on with.

 

[gunnergirl81]

Re: Teflon tape in barrel/action joint?

Go read the research Vaughn did. Its fascinating. By monitoring the stress on the receiver/barrel joint, and the relative position the barrel came to rest at between shots he could accurately predict where the next shot would go. He was working with barrels torqued to 300 ft-lbs, and managed to split recoil lugs! Its enlightening to say the least. But I'll have to get back to it later. Gotta work.

 

[wnroscoe]

Re: Teflon tape in barrel/action joint?

There's no reason why a guy or gal couldnt/shouldnt achieve proper thread fit between a barrel and receiver. The barrel in question could have been a take off and the thread fit was anything but perfect, Teflon tape to the rescue. I'm going out on a limb here and saying this

at 60,000Cu psi, I highly doubt Teflon tape will keep the joint tight. Harold Vaughn was ahead of his time.

Remember this, one day, someone is going to take a rifle apart and see what we left behind. Lets make it right the first time.

Phrases like "Thats good enough" "Cant see it from my house" "Good enough for who it's for" "Good enough for the girls I go with" and so on might be funny but, they have no real place in what we do.

Teflon Tape on a barrel joint

might as well be on suppressor threads as well.

 

[gunnergirl81]

Re: Teflon tape in barrel/action joint?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body"> "Good enough for the girls I go with" </div></div>

Hey now!

Maybe I'm just too optimistic and still a benefit-of-the-doubt giver. The husband sees enemy action in any error or anything suspicious looking. We're a good balance, I wanna trust everyone, he holds them at gunpoint until they prove themselves harmless (figuratively speaking).

The knowledge I've gained between him and hanging out here is phenominal. Knowing that if he's not around to ask a question to, that I can depend on many here to give a straight answer is like having more than one husband (without any of the inherent drawbacks).

Thanks again for putting up with another off the wall question.

 

[E. Bryant]

Re: Teflon tape in barrel/action joint?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">However, lets say you only achieve a class B threadfit, so there is some wobble/play between tennon and receiver... As the tennon shoulder butts against the receiver, won't the 60º threadform angle self-center the barrel to the receiver, thus providing the required receiver/barrel concentricity?</div></div>

In theory, yes; in practice, the friction between the face of the receiver and the shoulder of the barrel will prevent this self-centering from taking place, and you'll end up with something crooked.