Virginia rifle poi shift due to humidity?

[rich pierce]

Bend your pins very slightly and they will not slip.

[m1garand_man]

Dang it, I straightened them when I first ever took the gun apart because I thought that was wrong.

with straight pins they loosened up even more after slotting my under lugs. I'm guessing the original holes in the under lugs weren't lined up perfectly to start with.

Once I get set up with the tube for cleaning and have the bottom of the barrel and stock channel protected from moisture I'll stop removing the pins when I clean. I'm just having a hard time allowing stuff to seep in there and not deal with it.

[Daryl]

Suggestion for 'blackening" sights.

Pick up a black erasable felt pen. Much cheaper than the commercial aerosol can of 'sight blackener' and just as easily removed when you change lighting and need a brighter sight- just wipe of the dull black off the sight with your finger or thumb.

As the erasable felt pen ink is dull, it does not remain shiny as does permanent black felt pen on a smooth sight blade or bead.

[WadePatton]

If there's a bit of oil on the metal, the flame from a butane lighter will blacken sights nicely.  If you get your blade/bead notch all super tight for targets, you might not like them in the field for hunting.

Wood moves with humidity, metal moves with temperature. Slots allow this to happen with less binding.

It doesn't take "bending the bbl" to shift POI, it only takes resting your gun differently which can change two things: recoil path and the distribution/timing of vibrations (same as tension that could come from pins or wedges or firm wood contact).   You might vary your resting point to see if that changes your POI or group size.

You should be on the right track. I'm just saying this for target popping in general: Consistency in loading (volume and compression) and consistency in bench technique are paramount to removing as much of the human element of shooting in order to test accuracy of any load or gun. Shaders should fix lighting at the line, but also the target needs to be in consistent light. 

Then the wind. 

[smylee grouch]

I agree 100% with Wade. A lot of shooters don't take the consistency factor into consideration when working up loads or sighting in.

[Hungry Horse]

Surface finishes don’t slow down moisture very much, unless they have a good heavy coats of paste wax on top of them. And even then if the finish isn’t slathered into the barrel channel, and under all the hardware, moisture will start swelling up the stock, in wet, or humid weather. My first scratch built trade gun went from shooting center to shooting almost a foot high in its first rainstorm.
I stripped it and slathered it with hot linseed oil, turpentine, and beeswax, in every nook, and cranny. It never reacted to wet weather again. But, it did smell like turpentine every time I shot it several times in quick succession.

  Hungry Horse

[Standing Bear]

I recall 30 years ago asking my friend and world class shooter Tom Gillman why I had 2 groups on a target - one centered and one at 12 o’clock. He said “You’re getting older and there’s a ghost around your rear sight. Sometimes you line your front sight level w the top of the rear sight and sometimes with the ghost”. Got a Merit Optical Disc and it cleared up. you can move the rear sight forward or just shoot peeps.

[alacran]

I am fortunate to be able to shoot in the desert southwest and I the Midwest rainforest. I had a B weight 38 inch 50 cal. Rice barrel in a rifle that shot 1 1/2 inch high when I came to Indiana. I was shooting 60grains of 3f Goex in AZ. I simply dropped it to 50 grains and it solved my problem.  I have a 1inch ATF.  Douglas .45 that doesn't shift the POI. Two weeks ago I was shooting my cap lock pistol at the AZ state shoot. I was holding center of mass and grouping mostly in the black. Last week I was shooting it in IN with Little Joe. I was holding center of mass and was grouping at 6 o'clock below the black.
I believe the difference in light conditions, the difference in humidity as it relates to powder combustion as well as how humidity affects the stock in thin walled rifles, are all contributing factors in shifts in point of impact. That being said I don't argue with my guns I just adjust accordingly.

[Mad Monk]

Here's a picture of what I was meaning about taping the barrel where the pins are.  All you are doing is holding the barrel to the stock while the pins are out.  If the stock is changing or binding in any way, your accuracy could suffer.

Turtle: I wouldn't transfer my powder back and forth from the can to the horn.  This could be where the fines are created in your powder, or if you are using 2F and 3F you could get things mixed up.  (I know I could anyway - I keep my horns marked with what's in them.)  This is all just my opinion, though. 



upload album

When I was doing all of the powder testing I used to look at that.  But with the brands on the market today problems with moisture  getting into the powder are greatly reduced.  The powder today is shipped with a moisture content at about 0.5%.  If the moisture in the powder is increased you don't see much change in velocity until the moisture content goes above 1%.  At 1.5% there will be a noticeable drop in velocity.  As far as I know the three major powder makers are using potassium nitrate in the 99.9% purity range.  It is the purity of the potassium nitrate that determines how much moisture it will pick up and how fast it is picked up.  With 99.9% pure potassium nitrate it is relatively unaffected by humidity until the relative humidity goes above 90%.  ICI (C&H) used to use this to test their source of potassium nitrate.  Up to 92% R.H. the potassium nitrate picked up only a fraction of a percent of moisture.  Once the RH went above 92% it would pick up 1.6% by weight of moisture from the air.  Anything higher than the 1.6% would get that lot of potassium nitrate rejected.

This moisture pick up thing used to be a problem with Goex made between 1972 and about 2000.  They used a fertilizer grade potassium nitrate that had some residual sodium nitrate in it.  Only about 0.5% sodium nitrate but above 92% RH it would pick up about 16% by weight of water from the air.  These days none of the powder makers will touch any fertilizer grade potassium nitrate.  Oh how I remember the days in Tioga County with a flintlock after Christmas where the lock prime would go liquid in 15 to 30 minutes on the deer stand.  Real glad those days are over.  If the pan powder is made with the 99.9% pure potassium nitrate it takes a long time to get to damp to work right.

Bill K.

[m1garand_man]

Bill,

As always that was incredibly informative. Thank you!

[Mad Monk]

Bill,

As always that was incredibly informative. Thank you!

To continue a bit on that.
Few shooters today realize that the GOEX now on the market is a vast improvement over what had been produced in the old Moosic, PA plant.
The fertilizer grade potassium nitrate that Moosic was forced to use contained some residual unreacted potassium chloride.  The process used by Vicksburg to produce the potassium nitrate was only 98% efficient.  There was always some residual potassium chloride in the powder.  Of course then in the residue.  Making the residue extremely corrosive under certain conditions.  And chloride salts are noted for both rust films and pit corrosion.  When you read this think of the corrosive military primers used in the .30 caliber cartridges.  Primers made corrosive by a fraction of a grain of a perchlorate.  With the black powder residue well above that fraction of a grain in chloride content.  As far as I could see none of the black powders being made today use a potassium nitrate that contains any unreacted potassium chloride.  So while the powder residue might cause light rust films in the bore you will not see the nasty destructive pit corrosion seen in the past where they had to use a fertilizer grade potassium nitrate.

Bill K.

[m1garand_man]

That is also very helpful information. I do know about potassium chlorite from corrosive priming and have first hand experience in what careless cleaning results in with the stuff. I'm glad to hear I may not need to completely tear down gun anymore to clean the bp residue off ever possible nook and cranny.

I will say that the humidity in texas does have its advantages when it comes to keeping fouling soft in the gun. Which makes cleaning the lock a breeze with a damp cloth. That and loading remains easy even after the gun sits for a while between shots.

[Mad Monk]

That is also very helpful information. I do know about potassium chlorite from corrosive priming and have first hand experience in what careless cleaning results in with the stuff. I'm glad to hear I may not need to completely tear down gun anymore to clean the bp residue off ever possible nook and cranny.

I will say that the humidity in texas does have its advantages when it comes to keeping fouling soft in the gun. Which makes cleaning the lock a breeze with a damp cloth. That and loading remains easy even after the gun sits for a while between shots.

Humidity and BP fouling.
The solids left after BP combustion are about 4 parts potassium carbonate (potash) and 1 part potassium sulfate.  The behavior of the residue to relative humidity is dominated by the carbonate.  If the relative humidity is below 30% the powder residue is non-hygroscopic.  Meaning it will not pick up moisture from the air.  Above 30% R.H. it becomes increasingly hygroscopic.  Picking up more moisture from the air.  Once you get up around 90% RH it becomes deliquescent.  Meaning it picks up enough moisture from the air to form a liquid.  I used to watch this on the locks on my flint rifles and then used technical grade potash to work out the humidity figures.

Bill K.

[hanshi]

Humidity and BP fouling.
The solids left after BP combustion are about 4 parts potassium carbonate (potash) and 1 part potassium sulfate.  The behavior of the residue to relative humidity is dominated by the carbonate.  If the relative humidity is below 30% the powder residue is non-hygroscopic.  Meaning it will not pick up moisture from the air.  Above 30% R.H. it becomes increasingly hygroscopic.  Picking up more moisture from the air.  Once you get up around 90% RH it becomes deliquescent.  Meaning it picks up enough moisture from the air to form a liquid.  I used to watch this on the locks on my flint rifles and then used technical grade potash to work out the humidity figures.

Bill K.
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Bill, I saw that happen and never have seen it happen to such a great extent before.  This was at a woods walk in Petersburg and the humidity was very high and made the air feel "clammy".  After going through the lengthy shooting course I started cleaning my rifle.  Imagine my surprise when, before I even had a patch on the cleaning rod, a thick, black liquid poured from the muzzle.  Got to admit it did make cleaning the rifle a quick job. 

[Old Ford2]

Hi,
Always happy to see a new "Black Powder" shooter.
There is a tool, somewhat like a "C" clamp that you can use.
Remove your lock attach the clamp over the touch hole.
The clamp has a plastic hose that runs into a bottle/jar holding your soapy water cleaning solution.
You dampen a tight fitting swab screwed to your cleaning rod, and you pump it up & down sucking the cleaning solution out of the bottle/jar.
The barrel is not removed from the gun, your gun is clean.
Easy as skinning a cat with a dull knife.
It really is easy.
I believe October Country carries it.
Fred

[Daryl]

Track also has this device, or used to sell them.

[m1garand_man]

I recently bought one of these. I have to tie a string between it and the trigger guard to keep it from slipping up off the barrel flat (the stock on the opposite side of the lock is high)

But I get the rifle clean in about 15 minutes. I wish I had discovered this year's ago. I would have shot bp every weekend that way.

I am also surprised at how clean the water comes out even the first time. My patches apparently take care of a lot of the fouling. When I clean my civil war muskets (shooting 58 cal minie balls the water comes out considerably darker. Same with my bpcg guns.

What effect does pressure have on cleanliness of a black powder burn. I know with certain types of smokeless this is critical for optimal performance of certain powders.

Do heavier charges tend to burn cleaner? In my flint lock I'm shooting 80gr of 2f in a 50 cal barrel. In the muskets it's 65gr 2f in a .577 and a .58 cal.

[Daryl]

Good questions. I have read that 56% or 57% of BP results in solid fouling.  "Some" of that remains in the bore, thus makes sense that the more powder burned,
the more fouling will be produced, unlike some smokeless powders (balls/spherical bad) as you indicated.

I have always had less fouling from 2F in calibres .50 and over, than with 3F, even though 3F produces higher speeds and pressure.

I use very tight combinations, but have proven to myself, that 3F demands even tighter combinations due to it's rapid rise in pressure at any velocity.
Lyman's book of back in the 70's, shows this pressure difference in the one or two calibres it compared results. .54 seems to me.

I found, in my .69, that 2F produced exactly the same velocities up to about 125gr. as-did 3F(where I stopped the 3F), however 3F demanded thicker patching than did 2F after only 110gr.
With the 2F and standard .022" canvas(10oz) I could easily load to 165gr., however at 110 gr., I had to go back to my .030" denim patching or they had burn/scorch marks.
I was using a .682" ball in a .690" bore, with .012" rifling depth. Thus, the ball and patch had .004" compression from the oversize combination in the bottoms of the grooves
yes the higher pressure of 3f was causing burns and blowby.
There were no burns nor blowby with the canvas, thus, 2f, for me, is very much more forgiving.
In the smaller bores, I found that to get the same ballistics (accuracy and velocity)with 2F as 3F, I had to increase the powder charge by 10gr. - this was in .40 and .45 calibre - yet, 2F has never given me ANY fouling problems.  Some guys have written that 2F gives them more fouling. With my combinations, and Taylor's as well, we have never observed this 'phenomenon' of 2F producing more fouling as we never get ANY fouling buildup with either powder - not since reading Ned Robert's book & putting his teaching to practice - that would be 1973 or so, a year after I started shooting BP.

[Mad Monk]

To expand on Daryl's observations.

The amount of powder combustion residue that is found in the bore after firing the gun will vary.  I did a bunch of work on that years ago.  I had wondered why my standard lot of powder would give such widely varying amounts of residue in the bore after firing the gun.  The answer to that proved to be simple.  It relates to the maximum gas temperature as the ball moves off the charge.
I had noted in cold weather that the post firing bore residue was usually a very small amount of what looked more like as dust.  Then on hot days I would be faced with this tarry mess in the bore.
We are back to the behavior of the potassium carbonate in the powder combustion residue.  As the temperature of the gases behind the ball rise it will cause the minute particles of potassium carbonate to stick together into larger particles.  As the temperature rises these agglomerations of potassium carbonate begin to fuse.  If you look at a sample of the fouling under a microscope it looks as if little glass beads are in it.  And with rising gas temperatures these glass-like beads grow increasingly larger.
So the amount left in the bore is simply a point of fouling particle size and the ability to remain suspended in the gas before the projectile leaves the muzzle.  Larger particles cannot remain suspended in the gases so they settle out on the bore walls.  The really minute stuff stays suspended in the gases and is blown out the muzzle behind the departing projectile.  I even set up a funnel in front of the muzzle to catch the "smoke" and look at it under a microscope.  The smoke being the minute particles that had been suspended in the gases.
That also explained to me why some days the gun produced little smoke when fired and other days a big cloud of smoke.

Bill K.

[m1garand_man]

 So you feel that the ammount of smoke created is less tied to humidity than temperature?

[Mad Monk]

So you feel that the ammount of smoke created is less tied to humidity than temperature?

Actually both tie in on this.  The quantity of smoke produced depends on the amount of fine particulate matter ejected in the spent gases behind the projectile.  From what I found that gas temperature was greatly influenced by the temperature of the powder charge at the time of ignition.

The humidity comes into play after the solid particulate matter is ejected from the muzzle.  It will dissolve into the minute beads of water vapor in the air.  At low RH it hangs in the air for some time.  Few water molecules to run into as it drifts in the breeze.  But at high humidity as soon as one of the minute particles hits a water bead it dissolves.

Earlier in the day I remembered something from my powder testing.  Using different brands of BP under different weather conditions.  When I shot the rifle at 30 to 35 degrees about 2.5 to 3.0% of the weight of the powder charge stayed in the bore as post firing fouling.  But the same cans of powder shot at 85 to 90 degrees left about 15% of the charge weight as bore fouling.
This explained to me why some competition shooters shooting in very hot conditions kept their powder charges in a cooler until just before loading and firing them.  The rifles we can't talk about here.

Bill K.

[m1garand_man]

I recall when living in fairbanks alaska on windless days with temp in the negatives that the smoke would linger for minutes on end. We had bad temperature inversions which also act to keep wood smoke from people's houses in the valley in the winter too. The moisture content in the air at those times is extremely low. Here in Texas on a warm day the smoke doesn't hang around long.

I'm just curious how you were around be to determine the weight of the fouling left in the bore?

[Mad Monk]

I recall when living in fairbanks alaska on windless days with temp in the negatives that the smoke would linger for minutes on end. We had bad temperature inversions which also act to keep wood smoke from people's houses in the valley in the winter too. The moisture content in the air at those times is extremely low. Here in Texas on a warm day the smoke doesn't hang around long.

I'm just curious how you were around be to determine the weight of the fouling left in the bore?

I would take 10 heavy cotton flannel cleaning patches.  Run them through the kitchen oven at 250 degrees to insure total dryness.  Determined by weighing on a scale during drying.
Once cool I placed them in thick plastic freezer bags after weighing.
When shooting at the range I made them fairly wet and ran them down the bore fairly slowly.
I had found out that black powder fouling was 100% water soluble.  Just that sometimes it will dissolve faster than other times.  So I would run the 10 wet patches down the bore and save them.  Then once back home run them through the kitchen over at 250 F until total dryness.  Then weigh the 10 together to see how much residue they picked up.  Checked that out versus flushing the barrel into a container and drying that down to total dryness to look at how much it picked up.

Bill K

[smylee grouch]

That sounds like a neat time saving trick Bill. Thanks again for all your insight and participation in this forum. 

[Mad Monk]

That sounds like a neat time saving trick Bill. Thanks again for all your insight and participation in this forum. 

It did not end there.  Then I went down the barrel to different areas in the barrel to see where most of the fouling was being deposited.  Have that data stashed somewhere.

BillK