NEEDING BREECH PLUG TIPS

[Fox guy]

I ran the zero clearance bottoming tap down till it touches the shoulder of the rifling.  I know it bottoms because the perma blue covers the face.  I still can't get the breech plug to bottom.  I run it in and it tightens without bottoming.  Still 2/10 before the back of the breech meets the barrel.  What am I doing wrong or still need to do?

[J. Talbert]

Even a bottoming tap has some taper at the very tip.  I took one and ground the end until there was absolutely no taper on it.  I run it in AFTER an unaltered bottoming tap has reached its limit.
That may help.

Jeff

[T*O*F]

Your problem is most likely the breechplug itself which is not completely threaded.  It is necessary to countersink the end of the breech to make room for that final 1/2-3/4 revolutions of the plug.

[Herb]

Go to the Tutorials board, page 2, and read "Fitting a Hawken Breech Plug by Hand" by Herb, July 07, 2010.

[Long John]

Fox,

Here is what I do.  It is probably "wrong" in some other's eyes, but it works for me.

I carefully file down the first thread on the breech plug so that the threads actually start one pitch distance back from the face of the breech plug.  We want the face of the breech plug to seal against the ledge formed where the bore meets the breech threads.  The threads provide the compression force between the breech plug face and the barrel but they actually are not supposed to be a sealing surface.  By cutting back the threads one pitch distance I achieve sound sealing without all sorts of fancy machining.  I coat the threads with Lock-tite Blue when I  install the breechplug for the last time (after the vent bushing is installed).

Best Regards,

JMC

[Acer Saccharum]

I think TOF has hit on something which you really need to look at. The plug itself is threaded from the front, and the threads back to the vertical shoulders which form the tang. A threading die cannot run right up to this shoulder, resulting in incomplete threads . Often there is an undercut on the threaded section to get rid of these incomplete threads.

If your plug has incomplete threads, this will prevent the plug from screwing into the breech. You'll never be able to bottom out your plug if you have binding at the rear.

Two ways to fix it:
1)Undercut the plug
2)Countersink the back end of the barrel.

Another problem may be threads that are out of spec.
1)breech threads are small
2)plug threads that are too big.

You will need a tap and/or a die to fix this, or laboriously hand filing the plug threads to get proper thread fit.

I don't like the idea of hand filing the threads, just because it's easy to file too much in the wrong areas.

I hope this helps.

Tom

[Rasch Chronicles]

Out of curiousity, should a breechplug "bottom out" simultaniously with the back of the breech and barrel?

Best regards,
Albert “Afghanus” Rasch   
The Rasch Outdoor Chronicles’ Top Ten!
ΜOΛΩΝ ΛΑΒΕ!

[Dennis Glazener]

Yes if its properly fitted.

[bgf]

Just to be clear: mark the face of the breech plug and see if it bottoms against the rifling.  If the plug is too long, you will have to remove some plug length to get the rear of the plug to mate up with the barrel while maintaining the plug face seated against the rifling.

PS. Herb's tutorial is good.  Also search for posts from Dan Phariss and Rich Pierce regarding breech plug; those are very helpful as well.

[Bill of the 45th]

What Dennis said, and the flat of the tang will align with a barrel flat, and hopefully the stamping on the barrel will be on the bottom   So there is much more than just bottoming the plug to barrel walls.

Bill

[Acer Saccharum]

Original work: commonly the bore is barely smaller than the minor diameter of the thread. The tap was run in, then the plug was squinched right smartly home. There was no concern about butting the end of the plug against the bore.

This is blasphemy today.

There seems to be a modern consensus to butt the plug against the bore, and have the shoulders of the plug meet the back of the barrel nicely.

Is it necessary? Not for safety, in general, but boy, does it improve cleaning the gun after a shoot. There are no exposed threads to collect crud or rust.

Below is how I like to set up my britches. One more comment I'd like to say about this method is that when you have a really small breech,  you could compromise the safety if you drill and tap a lot bigger than bore size just to get that shoulder.

[Dphariss]

I ran the zero clearance bottoming tap down till it touches the shoulder of the rifling.  I know it bottoms because the perma blue covers the face.  I still can't get the breech plug to bottom.  I run it in and it tightens without bottoming.  Still 2/10 before the back of the breech meets the barrel.  What am I doing wrong or still need to do?

File the thread on the breech plug back about 1/4 to 1/2 a turn as needed this should let the breech face reach the bore.
Do not file in below dept of thread if even that deep.

Dan