Barrel and Breech plug question

[sundog]

I recently bought package deal that included a .32 CVA Squirrel rifle barrel, a TC Style breech plug , 9/16 drill and a 5/8-18 tap.

The barrels origional breech area is toast because the drum screw threads in the barrel are gone and the drum thread hole is greatly enlarged and the breech plug is gone.

The barrel is .780 across the flats.
The TC style 13/16 breech plug has 5/8-18 threads, the threaded portion of the breech plug is .900 long.

I can cut away the bad part of breech on the barrel and drill and tap to the proper depth and borrow a bottoming tap to bring the face of the breech plug into contact with the face in the barrel.

My question is about strength and safety. I am concerned about the barrel wall thickness in the breech plug area. After drilling and tapping it seems like there is not too much metal.

Since it is a .32 and we shoot light loads - never more than 25 grains in our .32s Do you think it will be a safe thing to do to install this breech plug in this barrel.

Many Thanks.

 

[MikeChapin]

My .32 has a 3/4" barrel and I used a 9/16" - 18 thread on the breechplug. This is just a flat flint breech and not a patent hooked breech.

I looked on TOW and there are patent breeches with a 5/8" - 18 for 13/16" barrels. Yours is not too far off that and it may work fine.

 

[Vaino]

If everything is "up to snuff" asre your drilling and tapping the threads and the .075 wall from the bottom of the threads to the outside of the bbl is maintained, I see no reason why this shouldn't be safe. A .32 cal. would exert 800 lbs of force on the face of the breechplug @ 10,000 psi and 1200 lbs of force @ 15000 psi and seeing these pressures are reasonable using BP, they certainly wouldn't even approach stripping the threads. However, the bbl is exposed to the load pressures and the .230 wall thickness is well w/in safe limits....my only concern would be the inside corner of the thread ctrbore of the plugface/bbl shutoff which could be affected by any expansion of the bore ID. Would I do what you contemplate?....no, but I think it'll be safe, but again, nothing is that certain considering unknown factors...Fred

 

[ron ward]

for what it's worth, being new here and basicly unkown, i would only question the method of drilling and tapping. if you can set the drilling up in a drillpress with the barrel held securly and then run the tap using the same setup and center index, i would say go for it.
a threaded mating gets its stregnth from fit as well as number and size of threads. i've tapped hundreds of holes in my life time, big and small, and the hardest part of it is getting the tap to start and and stay in line with the center of the hole so that it cuts threads that are actually the size of the tap. most times the tapped hole, or the major diameter of the threads ends up larger than they should when using a tap freehand. you loose allot of the thread's strength to the tap wobbling as you crank it. a proper tap handle, one with fairly long handles that alows you to feel if both hands are in the same plane as you turn the tap, helps allot to keep the tap properly aligned and not making oversize threads. go slowly, use lot's of lubricant and do everything you can to keep the tap from wobbling and tilting as you turn it. it is also important to have that long handled tap wrench so that you have allot of leaverage against the tap's cutting, the more leaverage (eg.,the easier it is to turn the tap) the easier it will be to keep the tap aligned for good, tight fitting and strong threads. pay real close attention to this alignment as you are starting the tap. many times, the tap is not started straight and the threading job is halfway done when it is realized that the threads are running crooked, at that point, leaning on the tap to gain alignment only causes the thread's fit to be loose, typicly 50% of the threads ultimate strength is lost with that type of "correction".
that's why criticle threads such as these, that need to fit well, are cut on a lathe. the finer the thread, the more criticl "fit" becomes. the idea that fine threads are stronger because there are more "teeth" doing the biting is only true when the fit is good.

 

[Holdem07]

Hi all, do you know where i can find a breech plug for a .32 CVA Squirrel Rifle? Or is there a replacement that will fit it?