Author Topic: Breech plug questions (Read 11528 times)

Ky-Flinter · « **on:** February 24, 2015, 05:27:57 AM »

I recently acquired a partially built rifle from the family of a retired gun builder. The rifle is done except for final stock shaping and carving. I decided to pull the breech plug to check it and here's what I found.

I think the notch in the breech plug face is too much. Do you agree, or would you use it?

I've been trying to think of how to fix the beech of this barrel and still use the already inletted stock. To do that, the touchhole has to be really close to the end of the barrel. I was thinking about cutting off the breech end of the barrel and fitting a TC style flint breech from TOW (picture below), cutting off the hook and welding the tang from the original breech plug onto the TC breech. Are there any drawbacks from using the TC style breech? Or is there a problem I haven't thought of? Any and all input will be appreciated.

-Ron

jerrywh · « **Reply #1 on:** February 24, 2015, 05:38:57 AM »

I don't like the looks of that. Not me.

mountainman70 · « **Reply #2 on:** February 24, 2015, 06:14:05 AM »

Might be better to re barrel with a new barrel and plug/tang,,then set up the relationships properly.I dont like the looks of it either. Then you could make a rifle fresh and re breech barrel,and use it,if it is any good. Dave

flinchrocket · « **Reply #3 on:** February 24, 2015, 06:47:38 AM »

D. Phariss has a good remedy for that problem, go to: page 2 in
Gun building- breech plug / liner safety questions- reply#13

E.vonAschwege · « **Reply #4 on:** February 24, 2015, 07:04:50 AM »

I've seen original breech plugs like that, but it's not a practice I am comfortable doing today. I will form a shallow groove into the face of a breech plug, at most about the equivalent of 2 threads, leaving plenty of solid threads remaining. This one is well beyond that - If it is a straight barrel, I would rebreech it and re-inlet it further back by 1/8-3/16". The patent style breech could work, but you still have the issue of strange geometry with the lock being that far to the breech end of the barrel.
-Eric

Ky-Flinter · « **Reply #5 on:** February 24, 2015, 04:51:05 PM »

The barrel is an early Getz swamped .45 cal, with lugs installed and drilled for pins, so sliding it back isn't an option. The stock is a nice piece of walnut, so I'd like to keep them together. The barrel is drilled and tapped for a touchole liner. The center of the liner is under a half inch from the end of the barrel, maybe .415" or so. (I'm at work, barrel is in snowed in garage.) The fence of the lock lines up with the end of the barrel.

Flinchrocket,
Thanks for suggestion. The fix Dan showed may just be the ticket. Much simpler and less expensive. For future reference, here's a link to Dan's suggested fix.... http://americanlongrifles.org/forum/index.php?topic=34254.msg328850#msg328850

-Ron

Turtle · « **Reply #6 on:** February 24, 2015, 10:03:58 PM »

I fixed a CVA? that someone tried to remove the breechplug without removeing the interlocking touchhole liner by cutting off the breech and adding a breech section like you pictured. it wasn't a TC. As I remember I got it from Track.
Turtle

Dphariss · « **Reply #7 on:** February 25, 2015, 01:57:55 AM »

This will work if there is not an oversized vent liner installed.

Dan

Dphariss · « **Reply #8 on:** February 25, 2015, 01:58:50 AM »

Might have to deepen the threads in the barrel a little.

Dan

jerrywh · « **Reply #9 on:** February 25, 2015, 06:17:10 AM »

Dans Idea is a great idea. That will work.

Ky-Flinter · « **Reply #10 on:** February 25, 2015, 06:47:53 AM »

Thanks Dan,

The barrel is drilled and tapped for a .250" OD vent liner. The center of the liner is .400" from the end of the barrel. The OD of the barrel breech is 1" and it's threaded 9/16-18, .500" deep.

I'm thinking the breech plug length needs to be .650" minimum. Should I enlarge the breech plug diameter? 5/8-18 or even 3/4-16? What would you suggest for the counter-bore diameter?

Thanks for your help.

-Ron

jerrywh · « **Reply #11 on:** February 25, 2015, 08:33:14 PM »

Personally I wouldn't enlarge the breech plug. I would just make it a little longer and make a hole in the side. The liner can either go through the plug or just go as far as the threads what ever is best. I have made plugs that were 1 1/2" long and put the touch hole outside of them. That may not be ideal but it works.

flinchrocket · « **Reply #12 on:** February 25, 2015, 09:35:47 PM »

According to my calculations, you should have 4 or 5 threads between the end of the barrel and the hole
for the vent liner, inside the barrel. If you do, you might get away with just installing a new breech plug
and open up the front for your touchhole. The plug you have may have had more material removed than was necessary because there are only 2 threads.

Ky-Flinter · « **Reply #13 on:** February 25, 2015, 10:11:09 PM »

Jerry,
Thanks for the reply. What's your opinion on the counter-bore diameter with the 9/16 OD plug? I'm wondering how much wall thickness I need to leave in the counter-bored plug.

Flinchrocket,
Thanks. I've been crunching the numbers too. The notch would have to be .225" deep on a .500" plug. Seems like a lot.

-Ron

Daryl · « **Reply #14 on:** February 26, 2015, 12:00:23 AM »

Quote from: Ky-Flinter on February 24, 2015, 05:27:57 AM

I recently acquired a partially built rifle from the family of a retired gun builder. The rifle is done except for final stock shaping and carving. I decided to pull the breech plug to check it and here's what I found.

I think the notch in the breech plug face is too much. Do you agree, or would you use it?
-Ron

I have seen this before - on a Made in India Brown Bess. It had 2 threads engaging in the barrel threads - one at .057"engagement, one at .022" and one at .002". I sent it back. They said they proofed it and it was fine.

I accepted the refunded money.

little joe · « **Reply #15 on:** February 26, 2015, 01:47:53 AM »

KY Flinter Are those sae. threads or coarse? They look coarse to me however sometimes a photo can be deceiving. I don,t think Getz breeched it.

flinchrocket · « **Reply #16 on:** February 26, 2015, 02:22:34 AM »

Sometime around the late 70's or early 80's builders got the idea that the fence on the lock should
line up with the end of the barrel. Original rifles with just a hole in the barrel made this possible,
however it doesn't work so well with a liner. I'm certain that's the cause of this problem. Getz probably
breeched the barrel, and I'm confident that they did a good job. I have used several Getz barrels from
their early years and were the first barrels that I bought that had the breech plug properly installed.
This is the work of whoever installed the touchhole liner.

Ky-Flinter · « **Reply #17 on:** February 26, 2015, 06:37:05 AM »

Little Joe,
National Fine (NF) 9/16-18 threads per inch.

Flinchrocket,
I agree. It looks like the breaching was properly done. The notch, not so much. I'm jazzed about the barrel. The serial # is 4370.

-Ron

flinchrocket · « **Reply #18 on:** February 26, 2015, 07:33:28 AM »

I looked on a couple of suppliers websites but they didn't give the length of their standard breechplugs.
I believe they are 5/8 in length (.625), that would give you .225 from center of touchhole to the face of the
plug and no barnyard manufacturing.

Dphariss · « **Reply #19 on:** February 26, 2015, 07:38:51 AM »

Quote from: Ky-Flinter on February 25, 2015, 06:47:53 AM

Thanks Dan,

The barrel is drilled and tapped for a .250" OD vent liner. The center of the liner is .400" from the end of the barrel. The OD of the barrel breech is 1" and it's threaded 9/16-18, .500" deep.

I'm thinking the breech plug length needs to be .650" minimum. Should I enlarge the breech plug diameter? 5/8-18 or even 3/4-16? What would you suggest for the counter-bore diameter?

Thanks for your help.

-Ron

"Cup" diameter is dependent on bore size. 32-36 cal then a 5/16 ball end mill will work OK. 40 can use 3/8 ect. Its possible to get ball end mills in sizes closer to the bore but they tend to cost more. So long as the cut diameter is at or smaller than the BORE it should work OK. Should be 4 flute.
However, you may need to center punch the plug when installed to assure that the cup is properly centered on the bore. I used a core from a 30 cal AP round set in a steel (polishes smooth beveled ends or brass "Sabot" about 1" long that fits the bore closely. Drop it down the bore a couple of times and the mark is made. Drill near finished depth then finish with a ball end mill at slow speed.
If its well fit and the face of the breech is coated with a felt tip marker it may be possible to check the senter in this way since the breech face will show the bore location.

This is a 58 after is been cut and you can see the groove location from fitting with felt marker on the breech face.

Dan

Dphariss · « **Reply #20 on:** February 26, 2015, 07:43:58 AM »

Quote from: flinchrocket on February 26, 2015, 02:22:34 AM

Sometime around the late 70's or early 80's builders got the idea that the fence on the lock should
line up with the end of the barrel. Original rifles with just a hole in the barrel made this possible,
however it doesn't work so well with a liner. I'm certain that's the cause of this problem. Getz probably
breeched the barrel, and I'm confident that they did a good job. I have used several Getz barrels from
their early years and were the first barrels that I bought that had the breech plug properly installed.
This is the work of whoever installed the touchhole liner.

The problem with this is if the rifle being used as a guide has the fence at or near the barrel breech moving it forward 3/16 or even over 1/4" can significantly change the way the gun looks in the breech/wrist area.

Dan

flinchrocket · « **Reply #21 on:** February 26, 2015, 09:01:31 AM »

Dan I agree that the fence should be at or near the breech end of the barrel, and with some locks it is
quite a challenge to use a vent liner while keeping the lock where it belongs.

Mark Elliott · « **Reply #22 on:** February 27, 2015, 02:19:36 AM »

I like my breech plugs with 1/2" of threads, and I don't like to cut into them at all. I also use touch hole liners and I make sure there is at least 1/32" in front of the breech plug. If the lock fence is 1/8" or 3/16" in front of the breech, so be it. I usually fill the gap with a little bit of wood. I have seen more originals than not that had such a gap and left it open in the lock mortice.

This is just my preference, and I figure it is a pretty conservative approach. That doesn't mean that it is necessarily unsafe to cut into the breech plug. I think a lot depends on how well the barrel is cleaned after use and how easy or difficult the modification to the breech makes that.

Scota4570 · « **Reply #23 on:** February 27, 2015, 10:21:04 PM »

On my current build I took off a thread to shorten and index. With the liner installed the lock is too far forward for my tastes. A while back somebody had the idea of making the plug as cap over the barrel. A female plug so to speak. That would make it possible to put the liner where you want and avoid a long flash channel or patent breech. Has anyone made one of these yet.

Bob Roller · « **Reply #24 on:** February 27, 2015, 10:37:02 PM »

Quote from: Scota4570 on February 27, 2015, 10:21:04 PM

On my current build I took off a thread to shorten and index. With the liner installed the lock is too far forward for my tastes. A while back somebody had the idea of making the plug as cap over the barrel. A female plug so to speak. That would make it possible to put the liner where you want and avoid a long flash channel or patent breech. Has anyone made one of these yet.

Ed Garrott in Beth Page TN made such a breech for a long range 451 and it worked OK.
There is NO mechanical reason why it won't. Ed is deceased for several years.

Bob Roller

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Author Topic: Breech plug questions (Read 11528 times)

Turtle