30mm Breechloader - Page 4 - Graybeard Outdoors
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post #31 of 47 (permalink) Old 05-17-2019, 04:49 PM
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Quote:
Originally Posted by double d View Post

I am surprised with the heavy charge and heavy projectile, that you didn't break something.

I'm surprised also.
Even well made carriages can't continually take a beating like that one is.
Something will fail.


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post #32 of 47 (permalink) Old 05-17-2019, 05:05 PM Thread Starter
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Originally Posted by double d View Post
If you will look at our sticky at the top of the board on safe loads and construction you will see the maximum recommended safe load for 30mm (1.181") is 200 grains of FG.

Try that and see if you have better luck. If you are shooting a lead projectiles with 1 oz of powder in a rifle bore then most likely your projectile is just stripping down the bore.

The rule of thumb for building cannons load is to start ridiculously low. Try a starting load of 100 grains and work up in say 5 grain increments.

I am surprised with the heavy charge and heavy projectile, that you didn't break something.
I was basing it on what the builder had said he commonly used. Sounds like I for sure need to cut down the charges. 200 grains is less than half the charge I was using.

I'm not very worried that the gun itself will break, as that barrel can withstand substantially greater pressure and the breech is pretty substantial, but I definitely don't want to have the carriage shake itself to pieces.

I'll tear down my prepared charges and remake them to a more sedate level and see how that affects it.
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post #33 of 47 (permalink) Old 05-17-2019, 07:16 PM
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Well, all I can say is I fired probably between 20 to 30 rounds is all. My recoil seemed less than what your video shows. But I usually was shooting on a sand surface or a grassy surface, rather than smooth surfaces. I think there is somewhat of an illusion maybe going on here. The carriage is light in actual pounds on a scale, but I do not think it has a strength issue because of this, if that makes any sense... It is going to recoil quite a bit because on the carriages overall lighter actual weight weight, . Hope my ramblings make some sort of sense anyway.



I will say after those 20 to 30 rounds over a couple years, not even the spokes have ever showed any hint of loosness. I would think that would be the first thing to show stress on the Carriage if it was going to happen.


Others have been into this stuff much longer than I and I respect their thoughts alot and I in no way am condemning their input, I respect it.. They know more than I will likely ever learn. I had just never personally observed any signs of stress anywhere on the carriage after firing it. Would it hold up for 4 years of constant use in a War, maybe not, but I was not in full battle with it either,LOL


I will agree it could use a heavier in actual weight Carriage,.. It sure would not hurt. But I do believe based on the rounds I fired and how it has held up, it is sufficient, but that is my opinion only based on first hand actual use of the Cannon.. I believe I have stated this here before. That carriage was not actually built for this barrel. It was originally built for a 1 Inch Bore Barrel I used to have in it. But is served me well for this Barrel also. And probably around fifty rounds on the carriage with the 1 Inch Bore Barrel too.



I think a lighter load sure would not hurt. I suggested that after it was stated that the rounds seemed to tumble and not stabilize. I was not suggesting the lighter load for worry of Carriage breakage though. That just never crossed my mind when firing it.


Oh I forgot, I always have some issues with the load chart, but what does it say for a 1.200 bore? I think it says closer to maybe around 220 to 230 grains for a 1.2 Bore?


I know it also says 500 Grains max for my 40MM Bofors Barreled Hughes. That is just plainly a insufficient load for my Hughes. .. According to the Chart, if I used those loads for my Hughes, 500 Grains would hardly get the Projectile out of that Hughes Barrel for me. The steels we are dealing with here in my case are so superior to the Iron and Bronze they had in the Civil War Era. It is no comparison between the two.


That chart is fine for stuff constructed in a traditional way, cast iron, Bronze and such, as it was in the day, but it just seems it is way to conservative to me when using modern steels in the complete construction of the Barrel, rather than a Cast Iron Barrel with a 1/4 inch steel liner. With a Cast Barrel I can see more caution needs to be used. But with these 4140 Steels used in these modern barrels we are talking here. You just simply cannot apply the same rules.


I am sure it is also intended to be on the very conservative side by the fella that wrote it. For obvious reasons.


Sorry for the long winded post too.
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post #34 of 47 (permalink) Old 05-17-2019, 08:38 PM
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FWIW, my charge is 250 grains of Fg in a 1.156" diameter smoothbore behind a 1.125" round ball diameter (about 2,066 grains from wheelweight alloy).

It's a stout but reasonable load and the most I want to shoot in that gun, any more than that recoil is an issue and I really don't want to wreck my carriage.

Blank loads are 500 grains Fg, foil wrapped, no filler or wadding.

Just my opinion: I think your charge and your projectile are both too heavy.

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post #35 of 47 (permalink) Old 05-18-2019, 08:49 PM
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Bruce, there is no doubting the 40 mm bbl is stout enough for your charge. But, a heavy charge is not necessary. I have to ask you, have you tried 500 grains?

The safety guidance for load development is to start ridiculously low and work up.

Never use someone else's load to start. That is a basic safety rule for all reloading.

In building loads you will be surprised how much distance/difference a small increment increase will give you and how small a charge increase will produce the result you want.

The 40 mm caliber, 1.575 inch calls for 500 grains of Cannon or Fg-about 1.14 ounces on the chart. That is for a lead round ball that will weigh about 5880 grains. You aren't using a round ball rather a heavier and longer slug. The way the round ball reacts in front of the charge of black powder is not going to be the same as the longer heavier rifled slug. The slug has greater resistance and is going to generate higher pressure.

Let me show by example how that looks. Click on the pictures to see video's.

Here is a 1 inch round ball that weighs about 1500 grs. shot with a 180 gr Fg charge.



Compare this with 1 inch, 9 ounce (3938 grian) cylindrical slug with the same 180 grain Fg charge.



Same charge weight, heavier projectile, greater mass, increase in pressure, more recoil.

Field carriages usually don't break wheels or spokes from firing. What breaks are trails or cheeks and associated hardware. When the cannon fires the barrel lifts up against the trail and capsquares. You can see that in the video above. Wheels usually break in transportation-going down the road.

Yes the chart can be hard to figure. The original published in the The more complete Cannoneer has an error on it that George removed several years ago.



Each small square going up the side equals .05 inch of bore or caliber.

Each small square going across the bottom represents 10 grains.

30 mm is 1.181 inch. The load on the chart shows a load between 240 and 260 grains starting load. Earlier I said 200, but that is not correct the chart says 240-260 grains. This is maximum recommended charge.

Were this my gun-30mm gun. I would set up a target made from one side of a refrigerator box at 25 yards. I would make a 6"-8" diameter black aiming dot right in the middle, top-to-bottom, left-to-right. Aim at the dot as best you can and use a starting load of 150 grains of Fg. Fire a couple of rounds and see it the keyholing goes away. Mark each shot hole after firing so you don't become confused with previous shots. Do not change your sights or your aim point during the entire test. Increase your charge 5 grains and shoot a couple more rounds. Repeat by increasing you charge 5 more grains, same sight sight setting and same sight picture. Continue until you either reach maximum or you get the accuracy you are looking for.

My guess is that you will find optimal before you get to maximum.

To help with accuracy be sure to raise your lead melt temperature and get your mould hot to eliminate the wrinkles. While the lead is melting, set the mould on the edge of the pot.

Last edited by double d; 05-19-2019 at 08:21 AM.
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post #36 of 47 (permalink) Old 05-18-2019, 09:30 PM
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Thanks Douglas, good info there.


I think I first tried 1.1 ounces. I think that was somewhere near or around 600 grains. It was pretty lackluster with that initial load. I think eventually I reached a max of 2.1 ounces. I believe that amount was just burning unused powered out the muzzle and wasting it. I now have settled on 1.7 ounces. That is what I fire now.



Being a Breech Loader. I do actually lose some umph just because of the Nature of the way a Breech is sealed in my Breech Loader. A Muzzle Loader is Completely sealed at the rear, other than the vent. So I just naturally lose some with the Leakage being a little more pronounced around the Breech Seal.



I cannot recall right off but I think my projectile may be around 2.1 pounds. I could be remembering that incorrectly.



The 1.7 seems like a decent load that I have settled on. Which I think is somewhere around 750 Grains.


I do know of some others with Breech loading Cannons that are using crazy loads in 40mm Bofors Cannons, that are much higher than anything I would ever contemplate.



I think Swistic actually had something to do with the fellas up North that built a Hughes with the 40mm Barrel like I did. I remember he may have atleast helped them with the casting of the projectiles. I can dig up the papers pertaining to this and what his contribution was for sure. Those guys initially figured and were actually firing I think 3 to 4 ounces in initial testing. Seems they settled on a amount around 2.5 ounces or a little more in theirs. When I read all this in the papers they sent me. I thought the amount they initially were using was really,really excessive in my mind. As far as I know, they did get away with it though. I never even thought of going that far ever.


In the research I have on the original. The documents show the original load may have been around 3 to 4 ounces firing a Bolt, not a round ball.That old information is probably what they based their original loads on in their reproduction Hughes..



They would have needed a pretty large load to get the original Guns to fire 3 miles up the Tennessee River I suppose. I still have some doubt they ever achieved this in testing. But the old documents I have, claim they did.
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post #37 of 47 (permalink) Old 05-18-2019, 09:35 PM
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Great comparison video.
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post #38 of 47 (permalink) Old 05-19-2019, 08:28 AM
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Sounds like you are are safe grounds there Bruce. Breech loaders are a different animal than muzzleloaders, still you need to be cautious, and so you are.
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post #39 of 47 (permalink) Old 05-19-2019, 11:12 AM
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I was going to suggest zinc, but I read back and saw the mold is aluminum. That would drop the weight from 14 oz. to less than 9.

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post #40 of 47 (permalink) Old 05-19-2019, 11:53 AM
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I also would like to get some Zinc rounds made for my 40mm. I have so far failed with my Zinc Casting deficiencies. I am going to try again soon since the weather is decent outside now. I just so far have not been able to cast good Zinc rounds. It just seems much more difficult for me than lead.
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