Author Topic: "Proper Windage" (Read 1819 times)

gunsonwheels · « **on:** May 09, 2011, 05:35:13 PM »

I am completely new to the forum and its culture so please forgive my inquiry if to others "it's obvious"...

Reading about "Proper Windage" in gun construction: Does this mean if I purchased a SBR replica barrel with a liner of 2.25" that I would have to have the liner rebored to 2.313" in order to shoot pool/billiard balls (2.25" +.005" -.000")

Is this an NSSA reg for smoothbores...

I know all the folks at Grayling shooting rifles have very close tolerance projectiles fitting in their bores and most, if not all have a rifle engaging skirt at the bottom of their projectile... as do most of the rifles shooting at the Casper, WY shoot each June. Some cast and then swage the projectile through a small cross-section piece of the rifled bore to imprint the rifling.

Whose rule is this and on what ranch would a shooter be prohibited from participating if he/she had tighter tolerances between the bore and projectile?

The mountain man clubs I started with had rules but two or more good reasons for each and every one of them. Projectiles rattling down bores while gas is escaping past the projectile seems a little obtuse to me... sorry if I offend $:-\$

Cat Whisperer · « **Reply #1 on:** May 09, 2011, 05:43:20 PM »

We generally consider the 1/40 of the diameter as being the proper amound of 'windage' (total clearance on the diameter).

Why? If you have no control over the 'roundness' or 'cylindricity' (technical terms from ANSI Y14-5M 1994) you MUST allow an amount of clearance that allows for variation in size of both the bore and of the projectile.

Windage prevents higher pressures from interferance between an irregularly shaped/sized ball, cylinder and bore.

It is a SAFETY consideration.

The smoother and more regular the bore (and the projectile) the better. As-cast is rough. Bored is much better. Reamed is even more better.

But since you have no control of what the next owner is going to do, keep to the 1/40 ratio - for everyone's safety.

rampa room artillery · « **Reply #2 on:** May 09, 2011, 05:46:18 PM »

the only rule the n-ssa has on smooth bores are that the projectile is made of a nonferrus material and you have to have a ball gauge the same size of the bore of your gun, for inspection the national inspector shoudl be able to push your ball with one finger through the ball gauge. or have it free fall through it. no measurements are taken on the ball or bore. soem shoot tight balls some shoot really loose balls. like 5.82 bore shooting a 5.5 ball. and have good groups. and some shoot turned aluminum round stock that is sized really tight like a rifle round. my pellots fro my rifle are .009 smaller then my bore. tight fit i really have to clean the bore in between shots but it works great. good 8 inch group at 200 yards.

rick bryan

gunsonwheels · « **Reply #3 on:** May 09, 2011, 05:54:14 PM »

My hypothetical question regarding the SBR line of tubes still stands. jer2349 would probably like the answer as well as he is just getting his Verbruggen up and would probably like to know if billiard balls are okay to shoot..?..?..? Maybe the answer is "very carefully"..? Or should he get the liner rebored to use that relatively cheap and redily available projectile??

I like the NSSA approach of checking it by free-falling the projectile through it... I am a fabricator and retired aerospace engineer so I am more used to controlling tolerances of the two rather tightly rather than providing slop for poorly controlled tolerances of either one or both. Loose goose is definately safer... but so is staying home.

And yeh I am a "redneck".....

gunsonwheels · « **Reply #4 on:** May 09, 2011, 06:34:11 PM »

Seamless mechanical tubing is controlled to an ID tolerance of +.000" to -.007" up to diameters of 2.5" (tighter for smaller stuff). Electrically welded is pretty loose at +/- .040" in the same size ranges. A Sunnen 850 sizing hone would be a good tool to open up a SBR tube so everyone might be happy. Billiard balls are controlled to +.005" so only a few thou would have to be relieved to make it all work to the numbers... except for the "one size fits all" 40/39ths. That would require opening that same bore to 2.313" instead of anything above 2.255"... what's the additional .058" (almost a full 1/16 of an inch) for... in case it gets run over by an Abrams out on the range??

I guess another question is as almost all rifled projectiles are specifically designed to "upset" somewhere near the bottom of the bore upon firing to expand a skirt of some kind into the rifling to obtain seal and spin of the projectile... how is that reconciled with the 1/40 D for "clearance"... rifled projectiles are dynamically conforming to their bore all the way up it and some I've known blow the skirt into a significantly larger diameter as they clear the muzzle (soft lead, hollow skirt, thin skirt wall and heavy charge).

Double D · « **Reply #5 on:** May 09, 2011, 07:06:50 PM »

If you look at the dimension of civil war ers cannon bores-smooth bores and the size of their projectiles you will find that the projectiles diameter is 39/40 of the bore diameter. I think Mueller also refers to 1/40 windage.

You 2.254 in bore barrel liner would need a ball that is 2.194 for traditional 1/40 windage. Experience Competitive cannon shooter will reduce the windage to achieve accuracy. Theat they very precisely guage the rounds and meticulously clean the bore when the shot. 1/40 is a good place to start.

The idea of windage was to allow loading of less than perfectly round balls under battle conditions. Windage also serves to reduce pressure.

gunsonwheels · « **Reply #6 on:** May 09, 2011, 08:09:18 PM »

I like your comment about battle conditions... dirty bores I am sure were impossible to avoid in battle. Watching a modern competition of rifles is almost like looking through the clear front panel of some dishwashers: rinse, pre-wash, rinse, dry, etc. No wonder they can reduce the windage from CW standards. Some of those guys really turn to it to extinguish residue and remove it thoroughly and to leave a dry bore to not influence the next charge/round.
It also is clearly a place to start and with poor tolerances and sloppy shooting and swabbing discipline clearly a place to never move from. I've served as a range officer a time or two and some of the "ordnance" people show up with to shoot is really scary.

subdjoe · « **Reply #7 on:** May 09, 2011, 08:15:51 PM »

Check this: http://arc.id.au/Cannonballs.html

BoomLover · « **Reply #8 on:** May 09, 2011, 09:29:45 PM »

subdjoe, that puts the question into an even clearer perspective, and makes perfect sense. I follow the 39/40 windage, because, as Double D said, it helps relieve excessive pressure. Like the man said, under Battlefield conditions, there wasn't sufficient time to measure each cannon ball as to whether it was a perfect sphere, and each grain of powder was not measured, only a specific amount necessary for propelling the ball in the proper direction of the target! Not to mention, there wasn't time to clean and dry the barrel after each shot, so, yes, windage is necessary to achieve optimum efficiency...am I being redundant, redundant, redundant? All in the name of Safety! BoomLover

gunsonwheels · « **Reply #9 on:** May 10, 2011, 05:52:34 AM »

The Coehorn shoots with a FIXED angle for elevation... the bed is leveled and the range is determined by varying the powder charge. Better control of the variables than the tables of the 18th century indicate, must have been required to enable the historically recorded accuracies of 19th century Coehorn crews. And mortar placements were usually farther back where time could be spent getting it right.
If the variables are controlled, safety is redily achieved by not overcharging that more closely controlled process. Talking to some of the folks who shoot smoothbore (cannon and mortar) at Grayling indicates some serious modification of the 18th century "windage" standards to their 21st century equipment and competition drill.
As for me, I am a newby to smoothbore having only done 40mm rifled ordnance and a BB mortar I am working on. I really do appreciate the forum's input as it has opened my understanding to just how steeped in history and tradition is the subject of windage.

Cat Whisperer · « **Reply #10 on:** May 10, 2011, 08:02:50 AM »

Quote from: gunsonwheels on May 10, 2011, 05:52:34 AM

...
And mortar placements were usually farther back where time could be spent getting it right.
...

In SOME places (notably Vicksburg) the range between the well-dug-in postions/lines was 100 yards or less.

brokenpole · « **Reply #11 on:** May 10, 2011, 10:20:51 AM »

Not kidding CW.

I am still amazed everytime I drive through that military park. There are places where I swear they could have had a good fight just throwing rocks at one another. They didn't need artillery.

gunsonwheels · « **Reply #12 on:** May 10, 2011, 11:31:13 AM »

Does this site have the pages regarding windage from Robert's 1860 manual for Artillery? ? Jim Bender referred me to them...??

Double D · « **Reply #13 on:** May 10, 2011, 11:40:53 AM »

It may be link in the reference section, that isn't my document, so I can't be sure. But here is a link to it , http://www.civilwarartillery.com/books/RobertsHandBookofArtillery.htm Section VII is about windage.

Artilleryman · « **Reply #14 on:** May 10, 2011, 12:10:08 PM »

In terms of using a gage for smoothbore ball projectiles. Ideally the ball should be able to roll through the gage with the gage being 2.5-3 calibers in length. It might slide through one time and get hung up another try.

gunsonwheels · « **Reply #15 on:** May 10, 2011, 01:41:01 PM »

Thanks very much DD for the link re. Roberts. He provides excellent info on windage and reasons for it, for reducing it and for expanding it... all really good info.

Lots of other relevant info to our sport as well

Thanks again

Rayfan87 · « **Reply #16 on:** May 10, 2011, 03:00:32 PM »

For smaller cannon (less than .50) has anybody tried patching? My dilemma is I have a 100ct box of .32 cal (.315) lead ball, and two .34 cal cannons<-----that one and the Dahlgren in the same series as that one (I've been waiting to finish it to post a "family" pic of the kits in the series). Would patching the ball work or should I melt them down to make cannon balls/rounds for a smokepole I'm looking at?

Parrott-Cannon · « **Reply #17 on:** May 10, 2011, 03:19:45 PM »

I have experimented with patching in my 69 cal. It works well. I wet swab then dry swab between shots.

Double D · « **Reply #18 on:** May 10, 2011, 03:29:18 PM »

Quote from: Rayfan87 on May 10, 2011, 03:00:32 PM

For smaller cannon (less than .50) has anybody tried patching? My dilemma is I have a 100ct box of .32 cal (.315) lead ball, and two .34 cal cannons<-----that one and the Dahlgren in the same series as that one (I've been waiting to finish it to post a "family" pic of the kits in the series). Would patching the ball work or should I melt them down to make cannon balls/rounds for a smokepole I'm looking at?

I patch everything under 75 caliber.

This issue of not patching comes up when you go above one inch. The large surface area of ball that large increases the friction and makes proper seating of the ball more difficult. It also increase pressure when fired.

For competitive shooting taking a knowledgeable approach of what is involved, there is some merit in reducing windage. But for the ordinary shooting most of of us do, there is a no need.

Cat Whisperer · « **Reply #19 on:** May 10, 2011, 03:57:08 PM »

To patch or not to patch.

For me, the issue is how smooth the bore is.

I have several golf-ball caliber mortars that do MUCH better patched - as the bore is 1.75". CNC made, the bores are very smooth and it also keeps them clean.

keith44 · « **Reply #20 on:** May 11, 2011, 08:40:49 PM »

A proper patch, with lube will also help smooth the bore over time, and many many shots. I've seen this with my muzzle loading rifles.

Cannoneer · « **Reply #21 on:** May 11, 2011, 09:47:20 PM »

If you're looking for increased accuracy with your smallbore cannon then use a patch. I'm going to be firing patched .69 caliber balls in the upcoming smallbore/smoothbore cannon shoot; it's got to increase the accuracy at least somewhat.

keith44 · « **Reply #22 on:** May 11, 2011, 10:03:24 PM »

that's my plan too, any other tricks you want to give away

Cannoneer · « **Reply #23 on:** May 11, 2011, 11:57:40 PM »

Quote from: keith44 on May 11, 2011, 10:03:24 PM

that's my plan too, any other tricks you want to give away

No. Double D's the one that I think still has some tricks hidden up his sleeve. Sure, he posted a couple tutorials on how to aim the tube without sights, but he's probably keeping a few secrets close to his vest. Why I'll bet he didn't even share some of this arcane knowledge with his good pal 1Southpaw.

Double D · « **Reply #24 on:** May 12, 2011, 04:32:39 AM »

I tell Southpaw everything....he never puts his hearing aid on so he never hears any thing I say...You should have seen us, or rather heard before I got my hearing aid. You could hear us in the next county.

Wet swab bore.
Dry swab bore.
stop the vent.
load patched ball,
Prime vent.
aim.
fire.

After the the first time shooting, do you think those OF's shared anymore secrets with me...

gunsonwheels · « **Reply #25 on:** May 12, 2011, 05:37:04 AM »

Again... I am really new to the forum but... seems something's missin' from your sequnce unless it's "inject liquid CO2 through vent to eject patched ball"
Sharing that sequence is NOT friendly

keith44 · « **Reply #26 on:** May 12, 2011, 06:27:20 AM »

Quote from: Double D on May 12, 2011, 04:32:39 AM

Wet swab bore.
Dry swab bore.
stop the vent.
load patched ball,
Prime vent.
aim.
fire.

Quote from: gunsonwheels on May 12, 2011, 05:37:04 AM

Again... I am really new to the forum but... seems something's missin' from your sequnce unless it's "inject liquid CO2 through vent to eject patched ball"
Sharing that sequence is NOT friendly

That's where the secret is hidden. Like priming and firing a flintlock, accuracy comes from consistent ignition. Lit by fuse or linstock, a softer ignition at least in flintlocks gives the best accuracy.

Zulu · « **Reply #27 on:** May 12, 2011, 07:38:11 AM »

I think gunsonwheels is saying that DD skipped the powder charge.

Now he needs the CO2 to get the ball out.
Zulu

gunsonwheels · « **Reply #28 on:** May 12, 2011, 08:30:52 AM »

YUP!!

Cannoneer · « **Reply #29 on:** May 12, 2011, 11:26:40 AM »

Quote from: Double D on May 12, 2011, 04:32:39 AM

I tell Southpaw everything....he never puts his hearing aid on so he never hears any thing I say...You should have seen us, or rather heard before I got my hearing aid. You could hear us in the next county.

Wet swab bore.
Dry swab bore.
stop the vent.
load patched ball,
Prime vent.
aim.
fire.

After the the first time shooting, do you think those OF's shared anymore secrets with me...

Quote from: gunsonwheels on May 12, 2011, 05:37:04 AM

Again... I am really new to the forum but... seems something's missin' from your sequnce unless it's "inject liquid CO2 through vent to eject patched ball"
Sharing that sequence is NOT friendly

Yeah, that could be considered a real bad idea to keep going over those instructions in your head when you were in the process of loading your piece; couldn't it? Hey, hold on just a secong here, didn't a fellow member have a problem doing just that, and with a steel ball no less; now, if only I could remember who that member was.