Author Topic: Standard 5/8" bolt fine thread specs (Read 1990 times)

preventec47 · « **on:** November 16, 2008, 07:59:28 AM »

I'm just trying to get an idea if the inside of the NEF barrels are
threaded with the industry standard fine thread pattern.

If so, it could conceivably make it a lot easier for us to simply machine
some new breech plugs starting with one of these bolts at 38 cents each.
They would need to be annealed and normalized for easy machining
but so what? It is easy.

http://www.allensfasteners.com/detail.asp?Product_ID=0014+5/8-18XGR5HEX

Ideally what we need is someone to get one of these bolts and see
if they will screw right into the rear of the late model muzzleloaders.
I dont have mine yet so will have to rely on someone else.

Thanks

Busta · « **Reply #1 on:** November 16, 2008, 11:35:05 AM »

Says it is a 5/8"-18 TPI, that is the size and thread pitch. Can you get one in stainless steel?

preventec47 · « **Reply #2 on:** November 16, 2008, 01:11:58 PM »

Busta, we havent established that NEF uses an industry standard
form factor even if they do quote the same size and threads per
inch. However it makes much sense that any machine shop adhere
to standards unless there is a reason they dont want to be standard.

Ref question of obtaining bolt in stainless steel? I probably think
so but it would be a mistake at this point of development. I'm
sure we all prefer stainless steel for the corrosion resistant properties
but there are many negatives associated with it from a manufacturing
and prototype development/testing standpoint. Strength is
absolutely not an issue as these plugs are stressed very very
little compared to the strength of the materials.
( and besides Stainless is weaker than heat treated steel )
Most Stainless steel alloys are very difficult to machine and
damage/dull cutter heads and drills etc. It would be much
smarter to work with hi quality but mild steels that could later
be tempered and heat treated at least during the development
and testing.
There are many sources of all kinds of speciality bolts and
fasteners and if the NEF barrels are 100percent conforming
to industry std size of 5/8 x 18 then we probably only want
to focus on bolts that have threads cut all the way to the
head and are too long so we can trim to length any way we
want. Tell you the truth, I wouldnt have a problem
at all with a steel breech plug that I clean after every
shoot and hit with a quick spray of oil of any kind
including used motor oil off the dip stick of car motor.

One of the problems I am having ( mentally ) is how
to create a .033 flash hole in stainless steel with a drill bit.
Stainless requires caribide or titaniaum nitride cutting
tips and no drill bit that small is that tough that I know of ?
Roughly speaking I've observed the flash hole to
be about the same size as small paper clip wire.

I've been thinking about our problem of inadequate
ignition and after reading about someone elses breech
plug having many flash holes and what they call the
"RING OF FIRE" it occured to me that is just what would
help us also. I think one reason for a small flash hole
is to prevent gunpowder granules from slipping through
right into the primer. Many small flash holes will
multiply the amount of primer flash by however many
flashholes there are and still prevent any powder
from leaking through.

Busta · « **Reply #3 on:** November 16, 2008, 02:21:06 PM »

preventec47,

I have some 5/8"-18 Knight plugs, they thread into the NEF/H&R perfectly. It is the length that is the issue, for proper headspace anyways.

This plug is the one I am looking to convert, as soon as I can find one or get some measurements. This one below is the old bare 209 primer plug that has been reintroduced as the Non-FPJ since the introduction of Blackhorn 209 powder. As soon as I can get some measurements from someone who has one, I'll be able to determine whether this will be an option. The primer pocket could be machined deeper to shorten the plug to the right length, I believe they will be on the long side by about .310". This would still allow us to use a 7/16" wrench/socket to install and remove the plug.

http://www.knightrifles.com/productdetail.aspx?id=900045

PHATINJUN · « **Reply #4 on:** November 16, 2008, 05:39:38 PM »

I got 5/8-18 SS bolts here at work I'll take a couple of dif ones home tonight and try in the morn. Should have socket cap ones also. Don't know why you guys didn't think of this earlier

Kurt

iowaforge · « **Reply #5 on:** November 16, 2008, 07:28:53 PM »

Mine is a standard 5/8 fine thread.
I put a standard fine thread bolt in there sometimes when I clean.

Busta, wouldn't the plug need a shoulder, like the original, and unlike the Knight, to "bottom out on" when tightened ?
The female threads in the barrel aren't cut all the way to the shoulder where the rifling starts, and that shoulder is quite
narrow, doesn't look like that would make a positive stop, or am I missing something?

Are breach plugs hardened?
An improperly hardened/tempered plug sounds dangerous. If the plug needs to be higher strength than mild steel,
how about an annealed or normalized alloy like 4140, are there any competent gunsmiths here that can answer this ?

I would like to have a BH plug made for my Sidekick, I've been waiting for some one to post a plan for making one (hint)
I would like it to be patterned after an existing design that works well, and specs out primer pocket diameter and length, flash hole size,
and how to measure for proper fit when closed on primer so I can have machining done only once.

preventec47 · « **Reply #6 on:** November 17, 2008, 12:48:12 AM »

Just a couple of comments on strength and headspace etc.
I am an engineer ( retired Lockheed with heavy emphasis on
structures ) and I can say that all of these plugs are the most
over engineered things in any firearm ever. The reason is
they are firstly engineered to provide a seal and having met
those requirements they are overly engineered by several
hundred percent for the stresses placed upon them in
muzzleloaders. Consider theoretically in a muzzleloader
that you machined off ALL the threads on the plug,
and then cut a S&W 500 chamber into the back of
the plug that would allow you to insert a S&W cartridge.
The Receiver is designed to handle ALL of the forces of
a cartridge that is 300 percent or more of the bore
thrust pressure of the muzzleloader without ANY
forces being absorbed by any threaded plug.

The only slightly stressed area of an NEF plug
is the very thin wall at the bottom of the primer
pocket where the flash hole is. Due to the size
in area and the muzzleloader pressures, this force
and resultant stresses would not exceed that of a
22 rimfire. I wanted to point this out when Busta
found his cracked plug but cosmetic reasons are
enough to want to replace something like that.

Regarding Headspace, and since our number one priority
is a good chamber seal, it is a foregone conclusion
that any plug we screw in form a good tight seal
and thusly any plug we use is going to have to
have a shoulder similar to the NEF plugs to mate
up properly internally.

My idea is to take a NEF plug and screw it in tight
so that we have the good seal and drill out the
plug totally end to end and with the use of a tap, create
the proper fine threads so that we can screw in
a 7/16 hex head bolt. Into this bolt we can machine
our primer pockets and flash holes etc. But mainly
once we have the 7/16" bolt inserted with the
primer pocket, we can then screw in and out the
7/16 bolt to adjust for headspace to fit our individual
guns. All we need to keep the 7/16" bolt snug and
with good seal is one or two wraps of teflon tape
around the threads before we screw it into the
NEF plug.

There seem to be one or two guys here with access to
some machining capability. I will donate NEF plugs
for the prototyping if they can get it done. On the
other hand, if they have that kind of access, there
is no reason why we couldnt just start with
regular 5/8" bolts. Either way at a cost of less than
$7 each, to save a little work we could use the NEF
plugs just for convenience.

Below are photos of the Plug Busta referred to a few
posts above

Busta · « **Reply #7 on:** November 17, 2008, 06:04:55 AM »

The breech plug will not need a shoulder, the only reason that is there is because of the primer carrier. The front of the plug mates up to the back of the bore, that is where all my breech plugs on all 12 of my inlines seal. You are right about there not being much surface, but the Knight 5/8" plug has slightly less and has been working since 1985 (MK-85). All that is really needed is a 5/8"-18 breech plug that fits the overall length with a bare 209 primer installed, with a primer pocket/flame channel/flash hole of course. It absolutely does not need a shoulder.

Busta · « **Reply #8 on:** November 17, 2008, 06:37:11 AM »

Just went and measured the distance from the back of the bore (where the breech plug seals) to the shoulder (where you guys think it seals) on the barrel, that measured 1.040". Measured the plug from the front edge (where it seals) back to the shoulder (where it doesn't seal), that measured 1.075". So your shoulder theory is not valid, that would mean there is a .035" gap between the shoulder on the plug and where you think it mates up. I already knew this, but figured I would give you the measurements as proof.

If you want to test this, blacken these to surfaces (front of plug and shoulder), turn your plug in tight, remove and check to see where it makes contact. The diameter of the front edge of the plug measures .566", no way is that going to fit inside a .501" or .502" bore to allow the shoulder to make contact.

preventec47 · « **Reply #9 on:** November 17, 2008, 06:53:56 AM »

Semantics always gets us since we dont have a special vocabulary
to work with. I was referring to the shoulder as the thin flat edge
on the front of the plug that mates and seals with the back of the
barrel bore that doesnt automatically exist at the rounded end of
an ordinary Hardware bolt.

I guess we have forward and rearward shoulders we can refer to the future.

In my mind I think of the material on the rear of the Breech Plug
as the head such as the head of a Hex Bolt. I believe the
only ( future) function of the head is to serve as the means to
grab the breech plug to screw it out.

As another item of discussion, since it has been said that many
of the 209 primers are of slightly different dimensions, would
we all want to agree on the most powerful primer as the
best dimensions to machine our primer pockets for ?

What mfg and model exactly would that primer be ?
I seem to recall the CCI but need to verify.
Thanks

Busta · « **Reply #10 on:** November 17, 2008, 07:21:18 AM »

Ok, we are on the same page now. The hottest 209 would be the Federal 209A, there are slight differences in length/diameter/rim thickness. The rim thickness is a moot point if not headspacing off the rim, such as the case of Hubbard 209 primer pocket. I am looking to headspace off the front of the primer. The Winchester W209 is the longest 209 primer I have measured. Of course all dimensions vary slightly a few thousandths from one primer to another, even from the same box (brand) of primers.

The T/C plug design is probably the best design I know of for Blackhorn 209, but their plugs are larger diameter than 5/8".

preventec47 · « **Reply #11 on:** November 17, 2008, 07:48:24 AM »

Busta,
I assume you intend to squeeze the primer into the
bottom of the primer pocket to obtain a good seal, right ?

Which T/C plug and why is it the best?
Is it the one with the multiple flash holes ?

Since NEF has to fit each barrel individually
since apparently all NEF receivers are not identical,
I think it is reasonable to assume in order for us to have
exact headspacing that we either adjust the barrels
the way they do at the factory or we have an adjustable
headspace breechplug.

iowaforge · « **Reply #12 on:** November 17, 2008, 01:37:26 PM »

Busta,
you are right. I was thinking about this during work and came to the same idea about the large shoulder being there
for the carrier, and if the Knight bottoms out on the unthreaded portion of the plug, the NEF could too.

I called Knight, and the tech told me Knight's breech plugs are 416 stainless, heat treated to
26-32 RC.

I like the idea of adapting an existing, quality plug.
Is there a way to measure the head space, or would it be remove a little at a time till it fits ?
I noticed on my Extreme's plug, the the primer pocket has a flat bottom, might need a lathe for that.
I wonder if one could grind a flat bottomed drill bit.

Busta, has anyone given you measurements from that plug yet ?

Busta · « **Reply #13 on:** November 17, 2008, 03:26:02 PM »

iowaforge,

Yes I got the measurement, it is 1.654" from mating surface to back of a Federal 209A Primer. I found out the newer non-FPJ bare 209 plugs by Knight are convex (domed), not concave like the FPJ plugs and IIRC the older version (pre-FPJ). This plug would be very easy to convert with a lathe. The knight primer pocket and walls would have to be cut approximately .140"-.144" deeper to bring the headspace to the same as the current NEF plugs length (1.510") with primer.

This looks like the best option out there in an existing plug, unless we can find some of the older pre-FPJ versions. The only thing that worries me is some of the knight domed plugs are not the best for Blackhorn 209, the reason I want this plug. I have a domed Non-FPJ conversion for my Knight Disc Extreme that works perfectly, just killed a buck Saturday 11-15 with it using 120 grains of BH209, Knight 250 grain USS PBT (Barnes TMZ), Federal 209A primer.

The plugs internal dimensions should be the same as this Disc Extreme Non-FPJ conversion plug, so if we have a tight lock-up it should work just as well.

preventec47,

Answers in red.

Quote from: preventec47 on November 17, 2008, 07:48:24 AM

Busta,
I assume you intend to squeeze the primer into the
bottom of the primer pocket to obtain a good seal, right ? right

Which T/C plug and why is it the best? Encore/Pro Hunter/Omega/Triumph/Endeaver all of them, take your pick.
Is it the one with the multiple flash holes ? No, that is not a breech plug, that is a primer holder/nipple.

Since NEF has to fit each barrel individually
since apparently all NEF receivers are not identical,
I think it is reasonable to assume in order for us to have
exact headspacing that we either adjust the barrels
the way they do at the factory or we have an adjustable
headspace breechplug.

Not completely, it is mostly the welded on under lug (space from the hinge pin to standing breech) that they are fitting, but if you want that perfect fit like I do, yes.

PHATINJUN · « **Reply #14 on:** November 17, 2008, 04:30:05 PM »

Don't have any 5/8"-18 all the fine thread stuff ends at 1/2". I do have fine thread All Thread or threaded rod and fine thread nuts but being you won't need that shoulder but for primer carrier I will not need the nut. Busta PM coming at ya. Kurt

Busta · « **Reply #15 on:** November 17, 2008, 04:33:52 PM »

Just got a PM from a gentelman at MM that has the old bare 209 (pre-FPJ) breech plug. It is 1.775" in length w/209 primer, it has a concave powder well that measures .307 deep. He has offered to send me pics, and I accepted. I also asked if I could copy and post the pics, hope to get a yes answer to that. Guess I'm not going crazy afterall. :lol:

Busta · « **Reply #16 on:** November 17, 2008, 06:38:42 PM »

As promised.

The actual plug is probably the same length, the new one has a convex (domed) face, the old one has a concave powder well and a pellet well. The dome is probably .120" or so. These plugs are for the plunger action inlines. Now to see if these are still available, or if the supply has dried up???

This is the old 5/8"-18 pre-FPJ 209 breech plug. This one could be machined down at either end, preferably the primer end, maybe just a couple drills and a drill press would do it? Would just have to go easy until you get the right depth, then remove some of the wall. Approximately .260" to .265" would need to be removed. Notice, this one has more meat on the walls of the primer pocket. Pics, compliments of Night at MM. Thanks!

Dooger · « **Reply #17 on:** November 17, 2008, 08:20:17 PM »

Keep me posted guys, I'm willing to buy one. Can't really help with the idea though, I'm illiterate when it comes to this type of talk.

preventec47 · « **Reply #18 on:** November 23, 2008, 05:22:16 AM »

Quote from: Busta on November 17, 2008, 06:38:42 PM

The actual plug is probably the same length, the new one has a convex (domed) face, the old one has a concave powder well and a pellet well. The dome is probably .120" or so. These plugs are for the plunger action inlines. Now to see if these are still available, or if the supply has dried up???
This is the old 5/8"-18 pre-FPJ 209 breech plug.

---------------------------
Just to be clear Busta, the photos you show here are of the old
version and it may not still be available. Is that correct ?

Busta · « **Reply #19 on:** November 23, 2008, 07:01:00 AM »

preventec47,

That is correct. The new version has a convex (domed) end.