Breech plug issue.

[bptactical]

Good morning, been searching for some info on a breech plug issue and looking for some advice.
I ran into an issue breeching a 58 cal Rice tapered barrel for my Stith J&S half stock.
Breechplug is a L&R 1 1/8" patent hook & tang. Thread is .750 x 16 TPI.
While running the plug in the 1st time (well oiled) for fitting it seized just shy of bottoming.
I was able to back it out but threads were damaged/deformed somewhat. Upon inspection at the bottom of the barrel threads there was appeared to be a burr.
I was able to dislodge it and it appeared to be a broken piece of a tap.
Damage to threads is mainly galling type damage with no missing threads and minor deformation.
I cleaned things out real well, re oiled and ran the plug back in. Threads in snugly and able to bottom on bore face. Worked it in and out a few times , a few particles were evident upon removal but with cleanup each time it seems burnished in decently.
I am reluctant to run a tap down the breech, dont want to chance cutting the threads oversize.

My concern is the possibility of the thread strength having been compromised.
I see a few choices:
Go ahead and finish fitting breechplug and run it as is.

Chuck up the breech plug and pick up the threads and chase them to get good clean thread profile (will yield slightly undersize threads) then chuck up the barrel, lop off the questionable breech threads and re breech/ re thread to fit the now undersized plug threads.

Get new L&R breechplug/tang, cut back barrel and thread for new plug-fit as required. Would prefer not to get new plug/tang due to expense and time involved fitting plug/standing breech.

Luckily I have not begun to inlet the tapered barrel into the stock yet so losing .600 or so in cutting the breech back will not effect stock fit.

Look forward to your thoughts

Thank you

[Bob Roller]

I would say the barrel was flawed,not the plug.It sounds like the chip from
the tap which would be a lot harder that the barrel or the plug was picked
up by the downward spiral of the incoming plug and then the damage occurred.
Those plugs are not hardened and this is an easily damaged item.You might need
another barrel or cut this one off and rebreech it with another plug if the threads
are really damaged.
Bob Roller

[D. Taylor Sapergia]

If you have been able to run the plug in and bottomed against both the shoulder and the end of the bore, and the top flat is aligned correctly, just carry on.  Build the rifle and forget about the incident.  If you are concerned about metal missing, seat the plug with Loctite.  But I would not be concerned.

[bptactical]

If you have been able to run the plug in and bottomed against both the shoulder and the end of the bore, and the top flat is aligned correctly, just carry on.  Build the rifle and forget about the incident.  If you are concerned about metal missing, seat the plug with Loctite.  But I would not be concerned.

Threads not horribly damaged, just a bit of the Crest of the threads rolled. Thread engagement is snug with no slop in threaded fit either concentrically or axially.
Plug is not final fitted yet, about 1.5 flats from that.

DT, I sent you a PM regarding under rib fitting.

[Daryl]

Thread engagement is snug with no slop in threaded fit either concentrically or axially.

Sounds perfect to me, however you don't have it bottomed yet, by the sound of it 1- 1/2 flats to go?

[45-110]

I ran into the EXACT same issue with my .58 Rice Hawken barrel 3 months back. Their threads where somewhat incomplete and buggered up at the bottom causing some galling while fitting the plug. Plus their ugly logo/twist stamp was going to index on my top flat.......no good. so i cut off 2 inches, put it in my lathe and recut-rethreaded it for the L&R breech. A heck of a lot of unnecessary work, but its done. The LR breech had 5/8" of usable  thread length whereas the Rice was threaded 1/2" deep......barely. Yes I called them but was told that's the way they do things.

[bptactical]

Slowly getting there, about 1 flat to go but face of the breechplug is not perfectly perpendicular with the threads of its shank. Have to work just the contact points instead of draw filing the faces.

[rich pierce]

Press on.  As they said above you’ll be fine, safety-wise.

[D. Taylor Sapergia]

Unless a breech plug is installed in a barrel when I receive it, I always bottom the threads.  I use a tap that I have purposely ground to finish the bottom of the barrel threads to get them as close to the end of the hole as possible.  I also run a die over the threads of the plug with the die reversed so that the threads get cut as close to the face as possible.  Then I go about fitting the plug to the barrel.  Don't assume that all this is going to be done for you on a blank barrel, or if you want to change out the plug with something you are providing.  And 1/2" of thread journal is lots.  5/8" is a pain in the toosh.