Author Topic: Question on maximum powder charge. (Read 1099 times)

russellwallace · « **on:** February 18, 2009, 06:58:42 PM »

Just fired for the first time my 2/3 scale 6 pounder.
The artilleryman recommends no more than 3-4oz of cannon grade powder for a 2 1/4 bore. Is this ultra conservative since they want no liability?

Russell

GGaskill · « **Reply #1 on:** February 18, 2009, 07:11:46 PM »

I gather you find something about 4 oz unsatisfying?

BoomLover · « **Reply #2 on:** February 18, 2009, 08:19:56 PM »

I use 1 to 2 oz in my 2 1/4 inch Howitzer, depending on whether I am looking at blank vs a projectile....how much noise do you want? What kind of distance are you trying for? How heavy are your projectiles? Quanity of powder is directly related to weight of what ever your shooting. Are you using Cannon grade, 1f, 2f? Always think of your safest load, versus your maximum load! BoomLover

Cat Whisperer · « **Reply #3 on:** February 19, 2009, 12:14:36 AM »

Quote from: russellwallace on February 18, 2009, 06:58:42 PM

Just fired for the first time my 2/3 scale 6 pounder.
The artilleryman recommends no more than 3-4oz of cannon grade powder for a 2 1/4 bore. Is this ultra conservative since they want no liability?
Russell

Russell -

WELCOME to the board!

Here are some of the issues and principles -

Maximum charge will have a greater effect on the metal of the tube than anything less than maximum. On the Army's 105mm and 155mm howitzers the tube has a log book and is meticulusly filled out for EVERY round fired. One can (or could when I was in the artillery) fire 4,000 rounds out of the tube before it cracked at the muzzle. Firing any charge less than charge 7 took 4 shots to count for one charge 7. I've met several that attested to the fact that the muzzle is checked at EVERY shot when near the 4,000 mark, and they said that cracks DID start appearing - one said a chunk of metal broke loose too.

The tables used to determine max charge are for safety. Use them, as they have kept folks safe - not a bad idea.

BUT, if you realy realy want to know what the max charge for your tube is you can determine it emperically. Take two more tubes IDENTICAL to yours. Load the first with a small charge and increase it until it bursts. Come down a step or two in the charge weight and repeatedly fire the second until it bursts. Use that charge for a smaller number of shots and you should be reasonably safe.

The problem is that the metal work-hardens with each shot and gets more brittle. Detecting when it fails is next to impossible. That is the reasoning for being conservative in what the max charge is. I have seen a bronze cannon (1" bore) explode - firing blanks - from about 12 - 15' away. You need to know when you light the fuse whether it's a cannon or a bomb.

KABAR2 · « **Reply #4 on:** February 19, 2009, 04:10:42 AM »

Sometimes there are those who don't know when to stop!

this photo was provided by Cannonmn on the thread below, this of course is in the extream........

http://i17.photobucket.com/albums/b62/cannonmn/miscforumsetc/forums%2010/3001-1.jpg

Rickk · « **Reply #5 on:** February 19, 2009, 04:53:40 AM »

3-4 ounces is quite a bit of powder in my 2 1/4 " barrels and makes me happy.

I use 3.6 ounces of "1F" with a couple of corrogated cardboard disks over the top for blanks, and use only cannon grade for live fire. My choice of 3.6 ounces is because my digital scale Overloads with 3.7 ounces in a waxed paper cup, and I figure 10% less than max is alot less stress on the barrel.

Double D · « **Reply #6 on:** February 19, 2009, 05:00:08 AM »

Quote from: russellwallace on February 18, 2009, 06:58:42 PM

Just fired for the first time my 2/3 scale 6 pounder.
The artilleryman recommends no more than 3-4oz of cannon grade powder for a 2 1/4 bore. Is this ultra conservative since they want no liability?

Russell

No it is not! It is maximum safe working load for modern guns firing a projectile.. War loads far exceed these loads and were for well for war. By exceeding these loads you risk breaking your gun. Recoil from maximum loads will quickly loosen and break things.

Why would you want to exceed this Maximum threshold any way? Can you answer that?

dynomike · « **Reply #7 on:** February 19, 2009, 08:08:57 AM »

Boom Lover what kind of metal are you using for balls?

dan610324 · « **Reply #8 on:** February 19, 2009, 10:41:26 AM »

isnt there an recomendation for max 1oz per caliber inch ??

GGaskill · « **Reply #9 on:** February 19, 2009, 11:51:12 AM »

isn't there a recommendation for max 1 oz per caliber inch ??

There are a number of recommendations for powder charges (including mine which is to make the length of the charge the same as its diameter ["square"]) but they are of limited use beyond a small range of bore diameters. For example, 1 oz per inch of bore diameter would be, in my opinion, too much for bores under 1 inch and too little for bores over 3". Also, granulation is an important factor. My rule for that is 1 inch and under, Fg; over 1 inch, Cannon. Other people have their own recommendations.

Unfortunately, none of them have any or recent pressure testing behind them and none are for the small bores that forum members generally use. Several years ago, I bought an Oehler Model 43 Personal Ballistics Laboratory to measure chamber pressure of "handgonnes" (this was during the period that discussion of these was rampant on this forum.) I haven't allocated the time to follow through with this project although most of the materials (except time) are present. Maybe later this year.

dan610324 · « **Reply #10 on:** February 19, 2009, 12:22:26 PM »

that would be extremely interesting , hope you will have time to do it .

approximately what preassures could it be in a bp cannon ??
yeah of course there are many variables such as powder granulation , charge weight , windage , bullet shape and weight , touchhole diameter , where in the bore the ball is on its travel .

but lets say a 1" bore with a zink or iron round ball and a 1oz load of cannon grade .
approximately where on the balls travelling in the bore will the maximum preassure peak be ??
the peak would appear sooner and be higher with an smaller granulation .

have there been any similar tests done in modern time ??
if so where to find any results from them ??

if you use a lead ball instead of iron or zink that would also increase the preassure because of its density and slower acceleration , but approximately how much ??

is it anyone here at the forum who could recomend any website where it would be possible to find any similar information so please let me know .
this is very interesting .

Double D · « **Reply #11 on:** February 19, 2009, 01:55:30 PM »

Actually, I'm not to sure that the recommendations of N-SSA and AAA aren't supported by pressure testing and especailly work done by Matt Switlik. Artilleryman might be privilege to that. Norm how about it, how were the max load tables for N-SSA?

GGaskill · « **Reply #12 on:** February 19, 2009, 02:09:24 PM »

I know Switlik ran some pressure tests in the '80's on full size guns but beyond those tests, I know of nothing except some tests run by Lyman for their blackpowder reloading manuals using a modified Colt-style percussion revolver. Those are pretty old too.

That is why I wanted to do some myself. The numbers wouldn't carry weight as standards but we would have more numerical data than we have now based on something that should be somewhat repeatable.

dan610324 · « **Reply #13 on:** February 20, 2009, 12:36:13 AM »

it would be very interesting to have some info in that area , if someone find anything in the net please let me know . Ive been searching but cant find anything .

dan610324 · « **Reply #14 on:** February 20, 2009, 12:50:09 AM »

russellwallace

please look at this pictures and think about it again , and remember that an bronze cannon most often are somewhat friendly when it blows appart while steel cannons or cast iron pieces turns to grenades and spread metal pieces all over the place .
so be very careful , DONT OVERLOAD .

dan610324 · « **Reply #15 on:** February 20, 2009, 12:57:35 AM »

here is the worst possible scenario .
remember that its well known that metal pieces have been killing people that been up to 100 ft away from the cannon .

if you are suicideable there are easier ways to do it , and who dont gives the cannon shooting hobby an bad reputation .

Double D · « **Reply #16 on:** February 20, 2009, 01:51:22 PM »

George,

Sounds like a great Idea, go for it!

Artilleryman · « **Reply #17 on:** February 20, 2009, 04:49:58 PM »

Quote from: Double D on February 19, 2009, 01:55:30 PM

Actually, I'm not to sure that the recommendations of N-SSA and AAA aren't supported by pressure testing and especailly work done by Matt Switlik. Artilleryman might be privilege to that. Norm how about it, how were the max load tables for N-SSA?

I helped Matt Switlik and Don Lutz with the pressure testing done I believe in the late 80's. There is a write up in the Artilleryman Magazine the has the results. We tested a number of loads using different powders and charge weights. We also used different types of projectiles. We used his Ordnance Rifle (3" / 10 pdr) I would have to go back an look up the details.

As to the methodology used to help develop the N-SSA load tables Matt told me once, but I would have to go back and talk to him again so that I would get the details right as I would not want to misquote him. The tables were revised some years back, and you can use a heavier charge if you use Goex Cannon grade instead of Goex 1fg.

rays89 · « **Reply #18 on:** February 21, 2009, 02:25:55 AM »

Maximum charhe doesn't always mean the most accurate charge. At least in other fields. IE firearms

irishman · « **Reply #19 on:** February 21, 2009, 10:30:32 AM »

The brass and bronze barrels above don't appear to have much in the way of wall thickness. I would like to assure anyone interested, my barrels at www.brooks-usa.com are not hazards. Actually, all over GBO, Brooks barrels are known as "overbuilt" by many. You can start at the Backyard Cannon Fun thread. Largely about Brooks built barrels.

There are many questions when one looks at cast barrels....first to mind is what is the porosity? What is the chemical composition? What is the skill level of the person doing the casting?

We use only FC360, same material with the same certifications as used to make components for NASA, USN and other critical users. Always the same chemical composition, always the same density.

These barrels are expensive. The material costs are up there and that's where the pricing of anything starts. I like to compare the cost per ounce with the cost of a prime steak served in a fine restraunt by a pleasant waitress. Now, compare the cost per year, after ten years, after fifty years, etc; and consider the pride of ownership as it goes from generation to generation. There is a lot to be said for making an informed decision, and the pictures above appear to be proof positive.

Michael

dan610324 · « **Reply #20 on:** February 24, 2009, 06:58:23 AM »

yes you are sure right here irishman , except for one thing , if you look careful at the enlarged second picture you will see that it actually goes well into the one cal rule , but if I remember correct that was an very bad casting . and Im not sure either of what alloy was used .
those pictures are just frightening samples as what can happened , doesnt matter if its steel , bronze or brass . in most scenarios its not the cannon that are dangerous , its the lack of knowledge .
if you have enough knowledge you dont do the dangerous stuff .

Im a bit scared when beginners start talking max loads , then it can be dangerous .
doesnt matter if its an good steel cannon or a bad bronze casting ,
unfortunately anything can be abused .

when it comes to barrel casting it takes both knowledge , experiance and equipment to be able to create the same conditions from time to time . but if its done correct with an suitable alloy it aint any problem .
at least they are much stronger then cast iron cannons , but of course not the same strength as steel .