Breach Plug threads too tight

[claytonroberts]

So I'm on my first build and am ready to install the breech plug. Its a Hawken plug from Track of the Wolf and a Colrain barrel both 3/4-16 threads. The first thread engages for about a quarter of a turn and then binds up. Every instinct is telling me not to force it, but I'm not sure if somethings wrong or if its just the nature of the beast. Ive searched the forum and have not found anything that clarifies it good enough for me. I read one thread talking about using a 12' wrench but it was not clear is they were talking about the final snug down or just getting the thing screwed down into the hole. Any help will be greatly appreciated.

[Shovelbuck]

Don't force it! something isn't right. It should go in easily.

[rich pierce]

I’ve often had to run a tap in. Kind of a pain and expensive to have to have a set of taps.

[Bill Raby]

I am with Rich on this one. Run a tap through it. But actually CHECK the size of the threads first. Just because Track of the Wolf website says they are both 3/4-16 does not mean that is what they actually are.

[smylee grouch]

Also, make sure your not cross threading it and use never sieze on the threads.

[sqrldog]

Better yet send it to someone that routinely breeches barrels and have it done correctly. I think TOW will do it for you.

[Bob Roller]

I’ve often had to run a tap in. Kind of a pain and expensive to have to have a set of taps.

It's more expensive not to have them and they are a one time expense AFAIK.
If I'm not mistaken,I think some of these plugs have threads cast into them
and must be redone with a die.Maybe someone who has seen this can say something.
Bob Roller

[45-110]

A  "H2 or 3" tolerance tap and die is almost mandatory when working around breeches.
They almost never go together properly as bought.

[mountainman70]

As I get older and hands sore,  I am finding it better to have this kinda stuff done by whoever I purchased from.
Especially the front and rear sights.
I have fit several of these breech plug, ,none have given me the fit you describe.
Have a goodun, Dave

TOP OF THE MORNIN TO yall.

[Herb]

Here is a tutorial on "Fitting Hawken Breech Pugs by Hand" by Herb. Go to Tutorials- Gunmaking and Metal Shaping-page 2-my tutorial.  You can buy a 3/4 x 16 tap AND die SET from Amazon for $18.99.  Or you can get that tap from True Value Hardware for $15.99 ( cuts the threads in the end of the barrel)  and the die (cuts the threads on the plug) for $10.99. See their web site if no store nearby.  You can order it by mail shipped free.  True Value web site- Tools- hand tools- taps, dies and extractors- taps- page 3- or back to dies.
Those parts are cheaper than shipping the plug and barrel to someone else to pay they to do it.  You can do this yourself.  Examine the plug and see if the threads look good.  Then the barrel threads.  But both probably need to be re-cut.  Any problem, contact me.

[Herb]

Here is a 15/16 .50 caliber Green River barrel I just fitted a plug to.  This uses a 5/8x18 tap.

Re-cutting the threads with the tap.

The threads are not cut all the way to the bottom (look at the tap above).  I cut the threads off the end of the tap with a Dremel tool and abrasive disk to make a bottoming tap.  That way the threads are cut to the bottom of the hole.

[Jeff Durnell]

Herb, couldn't we buy a bottoming tap? Just wondering if there was a reason for leaving the stub/part with the threads ground off, on there. I usually get taps in sets of three which includes the bottoming tap, but I don't know if I have anything as big as 3/4".

What are the common thread sizes used in breeches? 3/4 x 16, 5/8 x 18, what else? I'd like to make sure I had a set of each. You know.... better to have them and not need them, than need them and not have them.

[sqrldog]

The other common bp threads 9/16 x 18.

[Jeff Durnell]

Ok thanks. I'll get whatever I don't already have. Dies too.

[claytonroberts]

Thanks for all the replies. It really helped me get my head around the problem. I checked the threads with a thread gauge and they are all correct. I have a bottoming tap on the way and I think that will be the answer. I looked at the threads with a magnifier and the inside barrel threads looked rough and not deep and clean. Thanks again for the support.

[45-110]

there are taps and then there are taps. once you use a high quality tap/die you will never be able to stomach a cheap import or cheesy hardware store brand. the good ones are precision ground and sometimes tin coated. there is no mistaking the quality and fit of the finished threads.
take care of them and they will last forever, also use real cutting fluid.

[jerrywh]

Herb has done this the correct way. Bottom taps will ruin the seat if it has one.

[Herb]

Thanks, Jerry.  The tap has to have a taper if used to tap a drilled hole, which I don't need to do.  Rather than buy a bottoming tap, I just ground the taper off mine.  That was easier than cutting off the end of the tap.   I didn't know any better.

[Jeff Durnell]

Jerry, Herb,  I've been thinking about what you guys said and want to see if I understand this correctly. At first I didn't understand how a bottoming tap would screw up the seat. I'm just a mill mtc repairman, not a machinist  I have the taps sizes mentioned and the bottoming taps look perfectly flat on the bottom, but I think I see how that flat bottom, especially the corners created where the bottom surface and flutes meet, might dig/plow into the plug's seating surface of the barrel if any force were applied after the tap reached bottom. Is that what you meant could ruin the seat?

So shaping it like Herb did, and to a proper size, makes the bottom surface of the tap slightly smaller than, and clears, the bore and seat as the tap is run in?

Initially I was thinking that using the bottoming tap would be the way to go, but bottoming taps are the ones I always seem to miss most when I don't have them, and if doesn't matter which one out of the set I alter, I'll probably 'sacrifice' the tapered taps in these sets, unless there's a good reason to use the bottom tap that I'm not seeing.

Anyhow, does it sound like I'm on the right track here... or?

[45-110]

a bottom tap can, and will work fine. spot the plug in with Prussian blue or marker, maybe a slight chamfer on the last plug thread. the marker/blue will tell you when you have it properly seated. a large plug and small bore allows for a large flat contact surface, conversely a plug near bore diameter needs a little more finesse to achieve a proper fit on a almost non existent barrel shoulder.

[tiswell]

You can check to insure that the barrel thread is the same pitch, in case someone picked up a 3/4-10 at the barrel maker. Use screw pitch gages or jam a piece of clay in the internal thread and make an impression to check against the breach plug. Do this before you alter anything in case it has to go back.
                           
                                                                                                                                                                                                     Blessings, Bill

[FlintFan]

Without seeing the barrel myself, my guess is that the issue is only with the first female thread or so.  It is possible that the maker chamfered the barrel after the threads were cut, which would create a burr on the first female thread.  When you get your tap, just run it in a few turns and re-try the plug.  I'm guessing that might take care of your problem.

[Herb]

Jeff, the 5/8 plug hole shows very little shoulder, as seen in my first photo.  My tap still doesn't cut the last thread, at least the plug end thread has to be filed off to make it fit.  I smoke up the parts, turn the plug in snug, remove it, and file off the shiny spots on the end of the plug or thread until it fully bottoms.  a 3/4 x 16 plug  (for a one inch barrel) has a good shoulder to bottom against.  The end thread or two can be filed off without using a bottoming tap, it would still be a close fit.

[bob in the woods]

I really don't know why, but I have only had trouble with 3/4 -16 plugs .  The other sizes seem to work out, but every 3/4-16 plug /barrel has been too tight. I wonder if that size plug from T.O.T.W. is just off a tad ?