Breech plug install

romoshka · Monday at 10:33 AM

Ok, so I’m the fool (see Parts and instruction thread) who’s going to complete this Ky pistol. So you can see the breech plug is hand tight but lacks a few degrees of rotation to be aligned. I will assume that vise and wrench will solve this but my machinist education tells me I should add some thread locker. Another additional option I see is to drill and tap the underside for a set screw with small brass plug against the threads. What say the more experienced builders here?

Phil Coffins · Monday at 11:04 AM

Use no thread locker. I don’t use anything on breech threads at all. Toque to aline then put a witness mark on the underside.

ronaldrothb49 · Monday at 11:26 AM

You actually need to do the exact opposite. You need to put an anti seize grease on the threads. There is more to properly installing a breech plug then just screwing it into the barrel. You need to have the face of the breech plug mate up with the end of the bore sealing it at the same time that the tang on the breech plug mates up with the top flat of the barrel.

SDSmlf · Monday at 11:41 AM

romoshka said:
View attachment 368941
Ok, so I’m the fool (see Parts and instruction thread) who’s going to complete this Ky pistol. So you can see the breech plug is hand tight but lacks a few degrees of rotation to be aligned. I will assume that vise and wrench will solve this but my machinist education tells me I should add some thread locker. Another additional option I see is to drill and tap the underside for a set screw with small brass plug against the threads. What say the more experienced builders here?

Big NO to the thread locker, rather time for some sort of anti seize.

Is the front of the breach plug bottomed out in the barrel? Guessing with your machinist education you were taught to use something like Prussian Blue to confirm fit. Also, loose the setscrew idea.

And not that it matters, but went through a Tool Maker apprenticeship years ago.

Phil Coffins · Monday at 2:53 PM

Having a good fit and clean machining of parts are all that’s needed. All though I am a hobbyist now my back ground has formed my process of fitting things together. After gunsmith school I worked with one of my instructors building custom ordered Sharps rifles. Opportunities changed and I became a tool maker for a major manufacturer for fifteen years. Then moved and did most of the manual machine work for a company that built race cars from the ground up for ten years. Many people that have tinkered at home have developed all sorts of short cuts and well meaning ideas about what they like to do. Most of it is un-nessasary and harmless as long as they do the basic good work to start with.

ChuckJonesWagon · Monday at 2:58 PM

My only question that your pic doesn't show is, is the breech plug fully seated in the chamber inside the barrel?

When I fit a breech plug I use a transfer agent to make sure the plug is tight agains the inside chamfer that the drill left.

Eric Krewson · Tuesday at 8:50 AM

Timing a breech plug can be a tedious job, some that are good at measuring can take measurements and know a ball park figure of how much metal to take off the barrel and the plug to bottom out the plug in the breech and line up the top flat at the same time.

My system is to work on the plug and barrel a little at a time until I get the plug bottomed out and any barrel flat lined up as well as a seamless gap where the barrel and tang meet. Most of the time it is the top flat but if I get a perfect fit on another flat I go with it. I like to fit my plugs so they are finger tight to within 1/2 flat of lining up and bottom out perfectly with only 1/2 flat or less of wrench work and around 25 ft lbs of torque.

I didn't watch all of this but suspect it will explain how to correctly install a breech plug.

romoshka · Tuesday at 1:38 PM

Eric Krewson said:
Timing a breech plug can be a tedious job, some that are good at measuring can take measurements and know a ball park figure of how much metal to take off the barrel and the plug to bottom out the plug in the breech and line up the top flat at the same time.

My system is to work on the plug and barrel a little at a time until I get the plug bottomed out and any barrel flat lined up as well as a seamless gap where the barrel and tang meet. Most of the time it is the top flat but if I get a perfect fit on another flat I go with it. I like to fit my plugs so they are finger tight to within 1/2 flat of lining up and bottom out perfectly with only 1/2 flat or less of wrench work and around 25 ft lbs of torque.

I didn't watch all of this but suspect it will explain how to correctly install a breech plug.

Wow, thanks. That was indeed very helpful. As a super green (read ignorant as a box of rocks) I had no idea that the breech plug was to seat on an an internal land. Now with a bit more study I grasp the concept. I have a little metrology section in my home machine shop and it looks like I’m 0.145 off the seat. While I fully appreciate the craftsmanship of this fellow with a file I’ll be relying on my mill. Also as I begin to think about the initial manufacturing process as well as correction and fitment I found this video that explains manufactingberrors as well as 1 remedy method.

romoshka · Tuesday at 5:38 PM

Phil Coffins said:
Having a good fit and clean machining of parts are all that’s needed. All though I am a hobbyist now my back ground has formed my process of fitting things together. After gunsmith school I worked with one of my instructors building custom ordered Sharps rifles. Opportunities changed and I became a tool maker for a major manufacturer for fifteen years. Then moved and did most of the manual machine work for a company that built race cars from the ground up for ten years. Many people that have tinkered at home have developed all sorts of short cuts and well meaning ideas about what they like to do. Most of it is un-nessasary and harmless as long as they do the basic good work to start with.

You sound like a most interesting fellow.

beardedhorse · Tuesday at 6:12 PM

The video of German accented craftsman pointed out to have top flat of barrel where barrel maker's stamp is located line up with the top flat of your breech tang. Not all barrels are premium with no run out. If there is run out (the bore is not concentric or true to octagon flat) you must fit the breech plug so the run out points straight up or straight down, never 45 degrees or ninety degrees. A reputable barrel maker will stamp on top or bottom flat where a run out occurs if it is not a premium barrel. Premium barrels usually drill the blank first and then mill the flats concentric to the bore. Cheaper barrels drill the bore in a barrel blank that is already shaped with octagon flats and hope they can get close. Installing barrel in stock and sights on barrel with improper run out position will guarantee it will not shoot correctly at different ranges.

romoshka · Tuesday at 9:35 PM

beardedhorse said:
The video of German accented craftsman pointed out to have top flat of barrel where barrel maker's stamp is located line up with the top flat of your breech tang. Not all barrels are premium with no run out. If there is run out (the bore is not concentric or true to octagon flat) you must fit the breech plug so the run out points straight up or straight down, never 45 degrees or ninety degrees. A reputable barrel maker will stamp on top or bottom flat where a run out occurs if it is not a premium barrel. Premium barrels usually drill the blank first and then mill the flats concentric to the bore. Cheaper barrels drill the bore in a barrel blank that is already shaped with octagon flats and hope they can get close. Installing barrel in stock and sights on barrel with improper run out position will guarantee it will not shoot correctly at different ranges.

I’m loving and very appreciative of the insightful commentary the experienced folks here. However I’m not understanding the concept of run out up vs down or L vs R. I understand runout but how would I determine runout of the bore? From my teen years (long time ago) working on hot rods we used plastigauge to determine correct bearing size. I’m wondering about using it help determine breech plug seating.

Eric Krewson · Wednesday at 11:13 AM

Runout or off center bore, I didn't notice this until I was pretty far along on the build, Colerain replaced the barrel without question and let me keep the old off center one that I had already had jug choked. I gave the off center one to a friend who made a great turkey gun out of it.

Very few barrels made today have runout but it was common back in the day 50 years ago. As was said, the barrel would shoot just fine if the thick part was on the top or on the bottom, you could adjust the ball impact with sight elevation adjustment. A thick part on one side or the other would be problematical and cause your sight adjustment to be very off center on the barrel.

ChuckJonesWagon · Wednesday at 1:48 PM

I'm off more than that now-a-day.....I wonder if a wonky barrel would correct my wonky shooting because of my wonky vision and my wonky muscle control?

KSCrawford · Wednesday at 5:46 PM

someone pointed me to this guy on Rumble.
https://rumble.com/user/BillRaby
find him very good. I am going to start a build soon and plan on watch do watch do.
He has many builds you can follow.

tallPercshooter · Thursday at 9:07 AM

I think all these details about timing the breechplug etc. are nice, but hardly necessary. How many thousands of kits and homegrown rifles have the plug just tightened good in the breech until the flats line up, and call it good? They are perfectly safe to shoot and no one ever knows the front of the plug is not against a "shelf." I doubt the gunsmiths 150 years ago worried about this. Let the flaming begin....

Eric Krewson · Thursday at 10:31 AM

You are right T; I think it was Jim Chambers who said he examined a pile of vintage guns and found that very few had the breech plug fitted as exactly are we try to do now. For me is it just a craftsmanship issue. I fitted the breech plug my first gun build poorly, I have had it in and out a bunch of times over the years to get out a pesky dry ball or two and not found any evidence of leakage of any kind.

ronaldrothb49 · Thursday at 7:36 PM

Eric Krewson said:
You are right T; I think it was Jim Chambers who said he examined a pile of vintage guns and found that very few had the breech plug fitted as exactly are we try to do now. For me is it just a craftsmanship issue. I fitted the breech plug my first gun build poorly, I have had it in and out a bunch of times over the years to get out a pesky dry ball or two and not found any evidence of leakage of any kind.

I don't know one way or the other being correct. I will keep sealing the breech. I kind of look at that as a safety measure, I would rather be safe than sorry.
Many do obsess with the barrel channel perfectly fit to the barrel flats. In talking with individuals who have done restorations they have said it is not uncommon to find only the sides of the barrel are closely fitted the bottom 3 flats no effort was done to fit the flats the wood was just gouged out.

Dusty_Traveler · Thursday at 8:38 PM

tallPercshooter said:
I think all these details about timing the breechplug etc. are nice, but hardly necessary. How many thousands of kits and homegrown rifles have the plug just tightened good in the breech until the flats line up, and call it good? They are perfectly safe to shoot and no one ever knows the front of the plug is not against a "shelf." I doubt the gunsmiths 150 years ago worried about this. Let the flaming begin...

I agree with you.

Most of the antiques I disassemble have a groove filed in the breech plug where the fire comes in. There's no way a grooved breech plug seals perfectly against the counterbore. They built them all day like that.

Nor Cal Mikie · Friday at 5:52 AM

ChuckJonesWagon said:
I'm off more than that now-a-day.....I wonder if a wonky barrel would correct my wonky shooting because of my wonky vision and my wonky muscle control?

WONKY happens with age.

and it don't get any better.

Old Bear · Friday at 9:24 AM

Dusty_Traveler said:
I agree with you.

Most of the antiques I disassemble have a groove filed in the breech plug where the fire comes in. There's no way a grooved breech plug seals perfectly against the counterbore. They built them all day like that.

I did the same grove on my first York Pennsylvania no problems 14 years great ignition though.

Breech plug install

Help Support Muzzleloading Forum:

32 Cal.

69 Cal.

45 Cal.

Cannon

69 Cal.

45 Cal.

54 Cal.

32 Cal.

32 Cal.

Pilgrim

32 Cal.

54 Cal.

45 Cal.

32 Cal

40 Cal

54 Cal.

45 Cal.

58 Cal.

40 Cal.

32 Cal

Similar threads

Join the conversation!

Join today and get all the highlights of this community direct to your inbox. It's FREE!