short-breeched rifle.

[bonron]

  I'm not sure if this is where it belongs, so, admins. please move it to where it may belong.    I have a 40 cal long rifle that I bought in the white from a dubious character up in Michigan. When the vent liner was installed we noticed the breech plug was about 1/32nd short breeched. My question is one of safety. Is the rifle unsafe? I have been told that with proper cleaning it should be OK. Others want to put a brass shim on the face of the breech plug, of proper thickness of course. So. do I leave it alone and shoot it as is or do I face the breech plug. The load I have worked up and use for line shooting and hunting is 60 grs. ffG with a .390 rb and 18thousands patch. I know it's more than most 40cal guys use but I get 11/2" groups at 50 yds.  I will err on the side on safety first. What's your opinion.       Ron

[Acer Saccharum]

The breech gap is far more common than I like to see. I always, always check the breech fit before I inlet the barrel. It sucks to discover the gap after you've inlt the whole bbl, put lugs on, and pinned it to the stock.

In your position, I'd solder a copper or brass shim to the face of the plug. I've done that myself.

[bgf]

I am not an expert, but I would either re-breech (if you can find a longer plug) or shim the face of the breech.  Not sure why brass is always recommended for shim, as it seems to corrode faster than steel in presence of BP residue; I would probably try steel.*

In my opinion, it is not an IMMEDIATE safety issue (the threads are plenty strong), but the longer the threads are exposed, the more corrosion you might get, so better to seal them off as well as you can as quick as possible.

*No disrespect to Acer (who typed faster than I) -- I just don't understand why brass is always recommended in this application when the breech itself is steel.

[Acer Saccharum]

Brass and copper will compress slightly. I really never had a problem with brass corroding; but you could use stainless if you want. The point is to close the gap between breech face and end of the bore. Any gap there is a corrosion gathering undercut that is about impossible to clean.

[volatpluvia]

I once built a rifle with a Green Mountain barrel 15/16 across the flats and fifty four caliber.  I bought the barrel at Dixon's as well as the breech plug.  Because the barrel was that thin the plug was not bigger than the bore.  The threads were bigger, but what I am saying is that there WAS NO SHOULDER for the plug face to butt up agianst.  so I just turned the tang/bolster up against the back face of the barrel.  The first round of thread was exposed to the firing of the powder.  Later, after firing a trial session of several rounds at the range, I needed to unbreach the barrel, another story.  I found that the front face of the first round of thread was all blackened.  But there was no black beyond that.  There was no evidence that fire, smoke, or soot got beyond that face of the first round of thread.  So in my very limited knowledge of the time I pronounced it safe.
Now I know this is not the same as having a gap between the front of the breach plug and the shoulder it should be pressed up against.  I just thought I would add my experience to the mix.
volatpluvia

[Bob Roller]

 I would make a thin washer from stainless steel,not brass.

Bob Roller

[Ky-Flinter]

It may be too early in the morning for me to be thinking straight, but what about a shim made of aluminum?  What came to my mind was the washers that come with sparkplugs.  Aluminum doesn't rust and it would have a little "compressability", but I don't know what effect BP fouling would have on it.

-Ron

[Dphariss]

I'm not sure if this is where it belongs, so, admins. please move it to where it may belong.    I have a 40 cal long rifle that I bought in the white from a dubious character up in Michigan. When the vent liner was installed we noticed the breech plug was about 1/32nd short breeched. My question is one of safety. Is the rifle unsafe? I have been told that with proper cleaning it should be OK. Others want to put a brass shim on the face of the breech plug, of proper thickness of course. So. do I leave it alone and shoot it as is or do I face the breech plug. The load I have worked up and use for line shooting and hunting is 60 grs. ffG with a .390 rb and 18thousands patch. I know it's more than most 40cal guys use but I get 11/2" groups at 50 yds.  I will err on the side on safety first. What's your opinion.       Ron

Refit the breech by one turn. Only 1/16" to 1/18" set back.
Misfit breeches are a chronic problem with some barrels.
What you have is a fouling/oil trap that can lead to reliability problems when used with BP. If used with a powder made with potassium perchorate it can have serious effects and could result in a gas leak at the breech of the barrel due to the fouling eating a "crawdad hole" in the barrel.
Blackpowder is more forgiving but the gap is poor shop practice and I do not consider it safe. It would never leave my shop that way no matter what. Nor would I shim it.

Dan

[davec2]

I personally would not hesitate to shim the plug to fix the problem but would use mild steel soft soldered (or hard soldered) to the existing face and then re-machined to fit properly.  I have used copper before but, with frequent cleaning and wetting, bi-metallic corrosion can be an issue because of the electro-potential difference between the two dissimilar metals.  That would be especially true with an aluminum shim as it is more electro active in contact with wet steel than copper would be.  Mild steel on mild steel would be a fine method for filling the existing gap.

[bgf]

...
I have used copper before but, with frequent cleaning and wetting, bi-metallic corrosion can be an issue because of the electro-potential difference between the two dissimilar metals.  That would be especially true with an aluminum shim as it is more electro active in contact with wet steel than copper would be.  Mild steel on mild steel would be a fine method for filling the existing gap.

Dave, thanks.  I wanted to bring up galvanic corrosion, but I seem like enough of a nut most of the time anyway ; you have more credibility!  Mild steel will "crush" as much or more than the original breech material anyway, so it would be my choice also.

[davec2]

bgf,

Thanks for there vote of confidence, but my wife would often disagree with your assessment of my credibility.  She often says that I am full of (long pause)……..wisdom.  However, the voice intonations leave no doubt about the real meaning of the word "wisdom".

All the best.

Dave C

[Dphariss]

OK if you shim it.

Go to the hardware store and find a SS washer that is just under bore size. Probably a 3/8" or a metric if they have them. If they have them in bulk see if some are thicker or thinner than others.
Get a selection of 4-6 anyway.
Buy a 8-10" mill file.
Buy a bottle of STP engine oil treatment.
The OD is likely too great so find a 1.5 to 2" bolt that fits the hole closely. Make sure the bolt has threads to the head. Buy a nut for it.
Note, it may be necessary to file the nut and bolt head to a smaller diameter.
Now clamp one or three of the washers on the bolt with the nut center them as well as possible. Put it in a drill press or an electric drill and spin it up and file them down til they will clear the hole for the breech plug all the way to the shoulder. Install one and turn in the plug.  See how it fits, if you have various thicknesses (lucky) try the thick one first. If you come up one flat or a little less from the top flat remove the plug and coat with STP, threads and face not a lot just enough the cover the metal and screw it in with a 12" crescent wrench with brass pads double stick taped to the jaws. BE CAREFUL not to mar the top surface of the plug. Work it back and forth with moderate torque to see it its seating and pulling closer to the top flat. If it comes up with moderate torque you are PROBABLY OK.  Assuming the barrel maker did not use a common drill as a tap drill and the shoulder is flat this should work.  They have, depending on the maker of course, been getting away with sloppy breeching for a long time, most people don't look or apparently don't know or care what they are seeing. No, its not likely to blow out when used with BP. But its still poor workmanship and if used with chlorate powers can become a significant safety issue due to the fouling trap it creates.
Yeah you can use mild steel washers too but pickle them to remove the plating. Muriatic Acid from the hardware/lumber yard will do it in seconds.
Once this is done PROOF THE THING with  double service charge and TWO balls or a of about the same weight if you have one. OUT OF THE STOCK not in it.


This is a straight barrel, swamps need a different clamping to prevent bending.
Dan

[bonron]

Thanks a million for all your input. I will shim the face of the breech plug with mild steel soldered on. Those of us not as knowledgeable and experienced as you guys are really lucky and appreciative of your willingness to help us. Thanks again.   Ron