over-filed breech plug

[Don B]

I may have messed up big time.

I got a .40 Getz barrel with my Chambers York kit. The breech plug came match marked. I took it out to do the inletting, but wasn't able to generate enough torque to get it back in to the marks. The closest I could get was about half a flat short of the marks.

So, I decided to shorten things up a bit. I started taking material off the plug and barrel ends. But I fear I went a stroke or two too far. The plug shoulder seals well against the barrel end, and the plug end mates well with the barrel shoulder (Prussian blue), but at max torque, the plug goes about half a flat PAST the marks.

My question is, how do I know if I have enough pressure between the mating parts to seal adequately? Do I need to get another plug from Getz and start over?

Thanks for your advice. Don

 

[Birddog6]

If you have to go past it to make it tighten up good, you need another breechplug.

Originally (before getting file happy) you needed a bigger vice & a bigger wrench. If it went in one time, it will go back to the index marks. :thumbsup:

 

[shortstring]

If you don't have in any sights or touchholes, ect. you can just go to the next flat. Getz machines the hole to center & it wouldn't change anything. Of course you might want to tune up your filing a bit as you're going to run out of flats at some point.

Paul

 

[J.D.]

In this case, I think the dovetails are cut, so another breechplug is needed, or the plug and back of the barrel might be filed to rotate the plug a full turn. However, doing that could change the relationship between the barrel and lock inlets...as well making the tang inlet a little sloppy.

IMHO, I would call Chambers to make sure your barrel is a Getz, or order a new breechplug from Track or another supplier. IMHO, either way the plug will require some hand fitting. It depends on how much hand fitting you want to do.

God bless,
J.D.

 

[Don B]

If you have to go past it to make it tighten up good, you need another breechplug. :thumbsup:

Thank you all for your responses. Yes, the dovetails are cut on the bottom flat, so rotating a single flat is not an option.

But maybe there's enough pressure between the plug face and the barrel shoulder as is, even though I'm able to go another 1/16 turn past the marks? Is it a rule of thumb that max torque should bring the marks into alignment, but no further?

In other words, what does "tighten up good" mean?

 

[rich pierce]

Let's say you've got 18 threads per inch. A full turn takes up about .055. One flat moves the breech .007. Half a flat takes up .0035". There are a lot of folks running around with more of a gap than that betwen their breechplug face and the rifling, but they don't know it. Knowing it would drive me crazy, so I'd fix it. I'd rather go a full turn and have one less thread than have corrosion eating my breech threads.

 

[R.M.]

Rotating the barrel one flat might be an option, though you might not like it. With a full-stock, the dovetails won't be seen, you'll just know they're there. Extra work, yes, less than a new plug, probably not. Just another viewpoint.

 

[Roy]

I would take it around 1 full turn and fit it again. :v

 

[bob243]

If you have to go past it to make it tighten up good, you need another breechplug.

Originally (before getting file happy) you needed a bigger vice & a bigger wrench. If it went in one time, it will go back to the index marks. :thumbsup:

I could not agree more.. I ended up with an 8" Wilton mounted on my bench, and a 16" lineman's adjustable wrench on it to get the first one I did to line up to the marks that were on it.

 

[zimmerstutzen]

Other than taking enough offthe barrel and breech plug to do a full revolution.

Sometimes just a few pricks with a prick punch will raise the metal enough to draw tight a flat before it otherwise would. You may have to peen around the breech plug to raise that part to meet the inside shoulder. It isn't the best solution, but certainly doable.

A third solution would be to add a thin shim between the barrel and breech plug. A contrasting material like brass, so it looks like a brass inlay going around the back of the breech.

I once used the shim method, using very thin shim material, .008 it could barely be seen.

 

[bingo1952]

If you are going to go the shim route it is better to shim the shoulder where it butts up to the rifling down-hole. A Lead or Copper crusher will be more corrosion resistant than will Brass but if that is all you have it will work.

 

[Birddog6]

If you were to shim it, a stainless steel shim would be the material. However, by the time you find the right thickness, make it to fit, etc, you could have bought the new breechplug & learned to fit it & then know how to breech the barrel.
I don't like the idea of shimming breechplugs... To me the breechplug is fitted Correctly or it needs refitted. This is not a repair, it is a rework of poor workmanship from the manufacturer.
It is a new barrel going on a new rifle, I don't like starting out with shims & doing patchwork, I want it Correct from beginning to end. :wink: And there is no reason not to do it that way. Do it right, know it is right, and confidently go on. :thumbsup:

 

[Eric Krewson]

On a similar line, I am on my first build and the Rice barrel I bought had the breech plug so tight I used a 16" crescent and a couple feet of pipe to break it loose the first time I removed it. No way I could get it back in where it had been.

I took the barrel to a gun builder friend and he showed me how to breach it properly. It took about 50ftlbs of torque to install the breech plug after we worked on it.

There was about 10 thousands gap between the top of the plug and the barrel when we finished. Being a bit of a perfectionist I had another guy tig weld me a little metal on the top of the plug that I filed down to close this small gap to invisible.

In the course of building my gun, misdrilled hole in the tang, inletting, installing a white lightning liner etc, I have had the breech plug out a bunch of times. The thread fit is not as tight as it once was. When I installed the plug for the last time( my gun is almost finished)and coated the threads with anti seize compound I could take it to the last two flats by hand and only needed about 25ftlbs of torque to bottom the plug out.

This thread got me thinking, is my looser thread fit an indication that I might need a new breach plug and a tighter fit?

 

[Birddog6]

Again I say, if you got it out, it would have went back.. :wink:
Sounds to me like it is snugging up 2 flats off, it is plenty tight. And it is marks the face of the breechplug showing it sealed, that is all you need. :thumbsup:

:shake: No, I am not going to start checking them with a torque wrench...... You can talk to 25 builders & watch them breech a barrel, and every one will have his own method & his own variation of torque he feels necessary to do it.

:grin:

 

[Eric Krewson]

Thanks for the reply. I don't use a torque wrench but was a helicopter crewchief back in my old Army days. Everything was torqued on my choppers so I developed a calibrated arm, I can guess them within a few pounds even 40 years later.

 

[ApprenticeBuilder]

In my experience a dab of lubricant on the threads as well as the face of the breech and plug shoulder during the fitting stage will allow things to make up nice as dry metal tends to gall when it comes together under pressure.

 

[Vaino]

Not to question your torgue estimating skill and not being facetious whatsoever, all the bbls I've used so far {21} which included Getz, Colerain and my latest sole bbl supplier Rice, I've not encountered any breech plugs that couldn't be seated to the chisel marks w/ a 12" Crescent wrench. Granted some were easier than others but all were seated w/ the plug end touching the counterbore and the tang against the bbl. Perhaps I've been lucky? If I were in the bbl making business, I certainly would establish breech plug seating specs w/ a torque wrench in ft/lbs that could be managed w/ a 12" Crescent wrench. Something as you describe should be returned to the manufacturer and they would be grateful for the "return" in order to tighten their quality control......Fred

 

[zimmerstutzen]

gotta agree with Flehto, every time I installed a breech plug, it took a heck of a lot more than 40 lbs,




i remember using a breech plug wrench and a 3 foot monkey wrench. And tugging for all my 190 pounds. When i install a plug for the final time, I put a coating of never seize on the threads.

 

[Don B]

To clarify my situation, when the marks line up and the plug stops against the bbl, the plug end is seated on the bbl shoulder (using Prussian blue). However, from this point, I can rotate the plug another half flat using a moderate amount of force on a 12" wrench. My problem's very similar to Eric's:

When I installed the plug for the last time( my gun is almost finished)and coated the threads with anti seize compound I could take it to the last two flats by hand and only needed about 25ftlbs of torque to bottom the plug out.

This thread got me thinking, is my looser thread fit an indication that I might need a new breach plug and a tighter fit?

But if, as Birddog says, all I need is contact between the bbl shoulder and plug, then I guess I'm OK.

And it is marks the face of the breechplug showing it sealed, that is all you need.

I'm just concerned about my ability to turn the plug past this point with only a moderate amount of force on a 12" wrench.

By the way, my pre-filing difficulty returning the plug to its marks was with an 8" vise and a 12" wrench.

 

[bob243]

Your not clamping down on the threaded area with the vise are you? I usually put the barrel in the vise with about 2 or so inches of it sticking above the vise.