Pete:  I think many people that watch humidity don't have a good understanding of what it means and what it does to air pressure.  When you watch the local weatherman, he is reporting the amount of water in the air compared to what it can hold "relative" to a given temperature, thus RH.  As the day warms up, the amount of water vapor in the air dosn't change much unless a front passes over you but the RH goes down because warmer air can hold more water vapor than cold air.  If you want, I can give examples in numbers but it will take a while.  Many people that write BP lube reports say that when the morning started the temps were such and the RH was such but that the air dried out as the day warmed up.  Actually, roughly the same amount of water vapor was in the air but now it looks like there is less because the RH has gone down.  To me, that's why BP fouling is so much a temperature issue.  When the air temps go up, the barrel temp goes up so much faster.  I can huff and puff on the blow tube but I think the fouling dries out just as fast as I'm adding moisture.
Another fallicy that many people have is that warm moist air is more dense than cold dry air when just the opposite is true.  If you take equal volumes of water vapor and air, air will weigh more.  I think the reason people develop this belief is when the temps are high and the amount of water vapor is high, it retards evaporation on your skin and you feel hot and sticky thus they think the air is heavier.  A good example is a hurricane.  Very high temps and high moisture levels yet this is when the lowest barometric pressures are recorded.  Your findings on temperature are right along with mine even though I shoot BP.  As the day progresses, sight settings go up not because of air pressure or humidity, but because the temperature of our loads has gone up so velocity increases.  I learned that the hard way at my first Q.  I got a sight setting early in the morning on the buffalo, but by the time I shot at the buff for score, the temp had risen about 20 degrees.  I shot over it 3 times in a row without seeing any dust kick up because it was happening behind the target.  Finally, somebody clued me in but it was a valuable lesson.  As you probably know, once the Q starts there are no sighters.  Its not as much of a problem in LR shooting because when we move to the different yardages, we get sighters before we shoot for score.

Old-Win,

  I know about the humidity thing..... Now!  It kind of bowled me over when FAsmus told me that humid air is less dense that dry air. Seemed to go against reasonable thinking. But, he's a pilot and they have to know these things so took his word for it until I did some checking.

  But my shooting this year shows there doesn't seem to be much correlation between humidity and accuracy. If the humidity stays constant doing a test and the Temp. changes it will show up on the chronograph and target. If the humidity changes and the Temp. stays the same there doesn't seem to be any difference I can tell at 100 yds. anyway. I think this would be about the same if carried out to further distances if Barry's last message above is any indication.

  Here's a question for you that I don't have straight in my mind yet. Can warm air hold more moisture than cold air? Or is it vice versa?

  I think the warm moist air vs cold dry air issue just comes from people thinking that if there is moisture in the air it just has to be denser since water weighs more than air.

  I thought the temp. affecting accuracy and sight settings would also apply to BP as well as smokeless, but hadn't done enuf testing to say for sure. I'm glad your testing agrees with that. Possibly it affects BP shooting more, or faster than smokeless due to differences in barrel Temp.'s created. But if you discounted that you still have air temp. and that would be the same for both.

  If I'm gonna do some Shilouette shooting next year I gotta get this blow tubing down in my mind a little bit better. You're saying that you can huff and puff but you think that the fouling dries out when you stop. I would think that BP fouling being so hygroscopic that if you subject it to moisture it would tend to hold onto it. Especially in our neck of the woods. I recall that by the time I walked out to the parking lot at the NCOWS Buffalo shoot and ran a patch thru the barrel the fouling came out as a soup rather than a solid. As the barrel was cooling down it apparently was sucking in moisture from the air. I didn't think it was particularly humid either. So, I'm kinda confused by your statment. Care to fill that out a bit more? In fact "Blow Tube 101" would be much appreciated.

PETE

Good morning, Board;

O.K., Pete, you're down on your knees asking for it.  Blow tube 101 will take a whole career to learn.  Needless to say, I'm still a student.  However, I'll start.

I think there are really two things going on in the bore from blow tubing.  The first is to convert the fat and fouling into soap.  Once that reaction takes place, it is not going to reverse.

The second thing is keeping the fouling and soap moist.  The hotter the day and/or barrel, the more moisture you need to put into the barrel to convert the soap and moisten the fouling.  If you wait too long before firing the next shot, you may need to blow again to soften the soap and fouling.  Knowing how long that is can be a real trick.  I don't much worry about it during a relay because you're shooting more than a round per minute.  The rub comes when you shoot five and have to wait to reset the targets.  Then you may want to blow again just before shooting.  It depends on your gun and load.  Experiment.

How much to blow?  I kind of have a standard three long slow breaths.  If the day is hot or especially dry, I'll add a breath ... maybe two.  If the day is especially humid, I may only blow one or two.  When you start to clean after the relay, blow the same way you blew when you were on the line.  If the patch slides through easily, you're doing it right.  You'll soon develop a feel.

Quite a few of us have those little combo thermometer / hygrometer thingies from Buffalo Arms.  The actual relative humidity will fool you if you just try to guess.

Now, how to blow.  You see a lot of folks on the line blowing hard enough to make their face turn red, their eyes bug out and their ears wiggle.  That's the wrong idea.  A long gentle breath is better.  It's more effective in delivering moisture to the fouling and it's easier on the shooter.  Remember, the idea is to deliver moisture.  If the air passes slowly down the bore, you get a much better transfer than if the air just goes zipping past everything on the way out.

I know a number of shooters who take a water bottle to the line and suck on it every shot to keep hydrated and think it helps keep their breath moist.  It surely doesn't hurt anything, but I think it's unnecessary.  If you get so dry your breath is not moist, you have bigger problems than running a blow tube!  Drinking plenty of water is good for you, but doesn't help in this one instance, ....

Now, it will be interesting to see how many people have a different take.

Y'all be good.

horsefly

horsefly,

  Well, I've got my kneepads on so am ready for anything! 

  Enjoyed your post and learned a few things. I like the idea of "soap" being formed when you blow tube, but not sure I get where this idea comes from. As far as I know none of the new or old soaps are/were made entirely of ingredients found in BP. The closest I can imagine would be the old Lye soap, and I'm not sure I would want to leave any residue like that in my barrel for the length of a match as I've read some seem to do. Which brings up a question.... Aren't you guys afraid of your bores starting to rust if the humidity is high enuf it'll turn the fouling to "soup" if let stand for a short while?

  On using the patch to see if you are blow tubing the right amount. I've been keeping track of this and find that over 50% humidity a dry patch will push easily thru a bore after three long, slow breaths. When the temp. gets down into the 40's and the humidity is around 30%, using three breaths doesn't seem to cut it as you pretty well have to pound on the rod to get the dry patch thru. Even wetting it doesn't improve things to much. would you think more breaths would be needed, or?

  Can I get off my knees now? They're starting to ache! 

PETE

Horsefly,

  Yes... I'm aware that lye, and other old time chemicals were used in the making of soap. But I don't see the connection between soap and BP residue. All you've got is a little carbon, sulphur, and potassium(?) mixed together. Mostly carbon I would imagine. There are some soaps used in making some home made lubes, primarily as an agent to saponify it. Maybe some have fat in them, but I don't think the majority have. Might be wrong, so....

  What I was wanting to know is where do you get the lube and BP mixing together to form a "soap"? You're making a leap here I don't see, unless you know the formula's for all the commercial BP lubes out there and how they perform this "soap" making operation.

  BP fouling by itself is hygroscopic and would seem to me to not need any "soap" to soften it.

PETE

Horsefly,

  Thanks for your explanation. I've noticed this white residue on dry patches, but guess I'm never gonna get the relation to "white" not being carbon, or at least in great part. All you have to do is look at the burned out charcoal in your BBQ t osee that it's white. Wish Bill Knight was on here! Since the carbon makes up a great proportion of the BP it should also be a large part of the residue.

  I can see the fouling as being alkaline, but not being a chemist I don't see some of the things your putting forth as having anything to do with "soap".

PETE

PETE, Old-Win, feather, horsefly

First of few comments about my take on lube grooves and lubes. Not being a BP shooter my comments may or may not apply to BP.

As a bullet mould maker, the shape of lube grooves has nothing to due with with the cherrie cutting tool life or the amount of time required to cut the cavity, whether the grooves are round bottom and shallow or deep square groove. When I first made moulds almost 40 years ago, it soon became quite evident that shallow round bottom grease groove bullets released bullets more easily than square deep groove bullets from the mould. Remember that the alloy shrinks slightly in the mould cavity causing the bullet to grip the cavity. Even now when we make deep grease groove flat bottom bullet cherries they will have about a 3-5 degree side angle to allow the bullets to drop from the mould readily.

Grease groove depth and width, typically bullets of my design will have a GG depth of 5% bullet diameter (.016 deep for 32 caliber and width of .050 wide) rounded bottom. Bullets having only 2 GG's of this size and driving bands .120 wide provided enough lube and preformed as well as bullets having 5 GG's.

I beleive its important that excess lube be spun out of the GG's as the bullet exits the muzzle. The blackened (leaded edge) seen on the target is powder/bullet residue that is too minute to be spun off. We have all noticed that the first shot from a clean barrel does not display this residue edge, but a much lighter colored grey colored leaded edge. I have not seen any advantage to deeper or wider grease grooves.

With smokeless powders the bullet traveling down the barrel is lubricated more by the lube residue from the previous shot than the lube being carried in the grease grooves. Since the bullet seals the bore, the amount of residue left in the bore is the same regardless of GG size. To my way of thinking the residue left in the bore, is forced between the bullet and the steel of the barrel, much like the hydraulic wedge created in a journal bearing. I agree with you Pete that the rortaional force of lube against the bore while in the barrel plays a part in lubrication.

Any good bullet lube will have a high enough shear strength to hold up during the extreme pressures at the interface of the bullet and barrel surfaces. The consistancy of the bore residue changes with changes to temperature and humidity, this can vary with with lube formulas. As a schuetzen shooter, I breech seat the next bullet after firing as soon as possible to prevent fouling in the throat from hardening and also seal off air flow that might occur through the bore.

Powder fouling in the throat that is allowed to build up and harden will cause erratic muzzle velocities. Most schuetzen shooters are familiar with the black caking that can build up on the case neck if not cleaned off regularly. If allowed to build up this caking on the case is most difficult to clean off, this same condition occurs in the throat and at times in the bore at a point where the pressure peak of the powder occurs.This fouling build up is choking bore and works like a sizing die and will change the diameter of the bullet beyond the area of the fouling.

Thats my take on it  
Barry