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Discussion Starter · #1 ·
7" Treble-Banded Brooke Rifle (Double Dovetail Insert Making and Fitting)

Here at Seacoast Artillery Company we choose to recreate only historically significant seacoast artillery. We chose the 7" Treble-Banded Brooke because it was the only seacoast gun to ever penetrate a Union Monitor, the USS Weehawken. It also had the reputation among Confederate heavy artillerymen in Battery Marion on Sullivan's Island guarding Charleston, South Carolina, "as being able to hit a barrel at a distance of a mile with every pop".

Because of the reputed accuracy of the original cannon, we set a very high standard for the accuracy of our version of this famous, "Cannon Without Trunnions". Our goal was 5 shots of 9 oz. bolts at 100 yards inside 1.5 inches measured center to center. It took a full year to achieve this goal. Multiple test barrels were made and then test fired. We found as we changed the form of the rifling ever so slightly to almost perfectly duplicate Commander Brooke's original design, the accuracy got better and better. Finally the target displayed one, five leaf clover hole. This will be posted next spring after Brooke No. 1 is delivered to the customer.

Three trips to Ft. Moultrie on Sullivan's Island where the original tube now resides were necessary to recreate this tube 100% authentically. We have only the blacksmithing of the trunnion band breech strap to do and the tube will be complete. So, we figured that the oak upper carriage and the oak chassis and base should be started now.

Tracy and Mike



We hold a historical photo up to compare form and size of the upper carriage mock-up at close to the same angles and at a scale distance to that which the photo displays.





The tube is supported by the mock-up to see if there is really enough room under the breech so that elevation gear will fit along with the transoms and rear carriage lifting camshaft.




The final mock-up shows where the trunnions fit; a separate yoke showing wedge slot and female dovetail. The can is included for scale. The tube weight is about 100 lbs.





The unique and extremely accurate rifling is shown here along with our recreation bolt with the bronze ratchet base sabot whose ratchets mate with ratchets on the bottom of the bolt.

 

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Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

Wow!!! Neat!!!! Breathtaking!!!! 100 pounds and extremely accurate to boot; that's a big puppy. Can't wait to see the finished gun. Thankyou for sharing!!!!!
 

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Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

ABSOULTELY IMPRESSIVE!

I know what 100 lbs is - the tube and trunion of my 4.5" mortar weigh 103 lbs.

What's the bore diameter? (I missed the powder can!)

I am envious of your CLEAN shop (compared to mine)!
 

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Discussion Starter · #4 ·
Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

We can't wait until this big rifle is complete either, Ex 49er! It's been three full years on this one already, if you count all the various research efforts and you must. Glad you like it!

Tim, I knew your 4.5" mortar was a heavy one after you fired that first shot this past July 8th, because of the way it shook the ground! We are envious of all that cannon making material you have; if we had just 1/3rd of the raw material you have stashed in your shop, we wouldn't have to buy any for 5 years. The bore diameter of the Brooke Rifle is 1.1668" and what is far more important, the bore size is constant within +/- .0001" all the way up the bore. We really sweat the reaming process!! It is terrifically important to accuracy.

Ah yes, the Powder CAN. It will appear, as if by magic, later today. I just hope I can match Mike's artistry in metal with some of my own, in wood. Time will tell.

Regards,

Tracy and Mike
 

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Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

if it was more than a "PEEK" i'd pass out from excitement!!!! looking forward to seeing more, in fact can't hardly wait............ i've been saving pie plates, how many times do i have to hold them and let you guys shoot at them, to get a Brooke? darn sure hope all the groups are clover leafs :) :) :)
 

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Discussion Starter · #7 ·
Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

We are using the same scale as the first one, DD which is 1/6th scale. That's the only way we can keep the weight down to a manageable level for the customers who like to shoot their seacoast gun. But at about 140 lbs. total, including that 100+ lb. tube, it will be a two man set-up at the range. This weight is a lot more easy to deal with than the original tube. It weighed 21,290 lbs, making a crew of at least seven artillerymen necessary. Also, a 9 oz. bolt is a lot easier to handle than a 120 pounder!

Lance, how about three shots in each plate? Centered, of course. Reminds me of that 60s song, Secret Agent Man, "lives a life of danger..........." Trust us Lance, from now on, all groups will be clover leafs. ;) ;) ;) ;)


Good question.

Mike and Tracy
 

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Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

Amazing ! What a great barrel. I will be watching this one with great interest.
 

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Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

D2 is NICE stuff.

We used to make dies from it (8" in diameter) with cavities and punch/ram to make disk brake pads. Put 50,000 lbs pressure under great heat and the stuff melts together. D2 handled the temperature, pressure, impact and abrasion very well.
 

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Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

One tenth (I assume per inch) it tremendous accuracy. I'd say thats as good or BETTER than a Douglas XX air gauged barrel!

MANY rifle barrels aren't that good!
 

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Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

seacoastartillery said:
Because of the reputed accuracy of the original cannon, we set a very high standard for the accuracy of our version of this famous, "Cannon Without Trunnions". Our goal was 5 shots of 9 oz. bolts at 100 yards inside 1.5 inches measured center to center. It took a full year to achieve this goal.
This is remarkable accuracy

But to use you own words; " Here at Seacoast Artillery Company we choose to recreate only historically significant seacoast artillery... It also had the reputation among Confederate heavy artillerymen in Battery Marion on Sullivan's Island guarding Charleston, South Carolina, "as being able to hit a barrel at a distance of a mile with every pop"," in order to be histroically signifcant you are going to have to hit a 1/6 scale barrel at 1/6 of a mile.

Why do I think your gun is capable.


Could you post additional pictures ofteh trunnion detail. I'm not picking up how that works from the pictures you posted so far.
 

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Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

WHAT a research project.

First we need a 1/6 scale Whiskey barrel (or perhaps several - to ensure this is repeatable).

Then we need to EMPTY the barrel, carefully, with well documented observations regarding quality, arroma, flavor and so forth.

After that the shooting may commence; provided that there are gunners still stober enough to safely and accurately function.

Sounds like a Montana project!
 

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Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

I was thinking more along the lines of a 55-gallon drum. But a whiskey barrel would be more period-correct.

I found a company that sells 'personal-size' oak barrels. A one-liter barrel is approximately one-sixth scale of a full sized whiskey barrel.

Barrel Source

The dimensions of a one-liter barrel are 6½" x 4½".

So the Brooke Rifle would need to be able to consistently hit a target 4½" by 6½" at 880 feet (293.3 yards).

The little barrels start at $25 each (sorry, no beverage included).
 

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Discussion Starter · #14 ·
Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

Thanks for your kind words, Rich, Tim and Douglas; we do appreciate them. First of all we are happy to hear that D2 steel is actually used for punches and dies. Punching is probably closest to what we are trying to do with common boiler plate in our recreation of the old time armor penetration tests. Tim, we are very glad that you told us about it's actual use for this purpose. Machining the ratchet shapes in an annealed rod of the proper turned diameter should not be difficult and also drilling and tapping the central bolt hole followed by heat treatment in our Ebay furnace. Have to read up on that! According to Commander Brooke, in his testing on wrought iron armor plate, he made claims of 8" penetration at any range less than 500 yards with 120 lb, wrought iron bolts propelled by 20 lbs. of Navy BP. For us, that maximum charge would be 648 grains of Goex BP. Too cold and windy now; the Brooke Rifle VS Monitor turret tests will commence next summer.

As for accuracy, we really can't identify the single most important factor, but probably that $250 reamer has something to do with it and some very slow and careful reaming. Mike made a 30 lb. monoblock to hold the gun drills and reamers which helps dampen any minor vibration. The Sterling Gundrill Company supplied the water-sol coolant and misting pump unit which works like a champ. We never deviate from a set routine which uses optimum speeds and feeds for drilling or reaming. Eliminate the variables and a good result can be had.

We use both Mahr and Mitotoyo bore gages with minimum extensions and they calibrate good after each use. We check every inch and you are right, Tim, the spec is .0001" per inch max variation with a total of .0005" allowed. What we get, however, is much better than that at +/- .0001" for a total of .0002" in the entire bore length which is 22.667". We gundrill and ream a bore that is a full three inches longer, 25.667", than the finished 1/6th scale bore will be. One further thing we do really gets rid of anomalies in the bore size. We part off the extra three inches of the tube after rifling is complete. The rifling head is partially, from 20 to 80%, unsupported in the last two inches so variation can and does occur. We take that two inches AND another full inch off to make darn sure that the all important muzzle area rifling is near perfect and NEVER larger than any other place in the bore.

The solid steel bolts we use are made from 12L14 steel which can be easily and accurately turned to close tolerances and we do exactly that. Mike is trying to make a better than average machinist out of me, so I get this job quite often. I am much slower that he, but I rarely make mistakes. We inspect each piece as it is made, and typically reject one or two out of a batch of 30 that we make per 4 hour session. We weigh every powder charge and have standard patterns for the aluminum foil powder bags and a standard way of making each one. Other than the rooting out all the variables in every process, I don't think we have any real SECRET to tell you fellows.

Double D, we don't think that hitting a 1/6 scale whiskey barrel at 300 yards would be too much trouble, in fact we will try that at the Montana shoot, even if we have to make the small barrel !! That would be fun to try. As for the other pics of the trunnion detail, we can take the trunnion band off the tube to get some pics and also show how that piece is keyed into the second reinforcing band layer. The strap is only half formed, so it's connection to the yokes will have to wait until we make yet another fixture for the 20 ton press.

As for the barrel draining we will need some spectators to accomplish that task. Volunteers should not be hard to find. WOW, those are really nice barrels, Terry C. Top notch; they are so cute we would hate to put any holes in them. ;D ;D ;D ;D

Best regards,

Mike and Tracy
 

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Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

Hmmm... Blasting a hardened steel projectile without a forward brass band on it might not be the best way to preserve the precision of the bore you have worked so hard to achieve.

With the machining of the interface between the base and sabot it's an expensive enough bullet already, but you might want to consider coating the steel with something so that it will not damage the bore. I would at least polish it where it meets the bore and lube it.
 

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Discussion Starter · #16 ·
Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

You are right on the money, Victor3. What we failed to mention, is that we have four practice barrels to choose from in order to do these tests. You are correct; it would be foolish to take a chance with that super accurate, first production tube. All except for the first practice barrel would be able to hit a one foot square of boiler plate at 83 yards, no problem. If we were going to do it we would polish the heck out of both bourlette bands. Some people think we are weird for even using the extremely malleable 12L14, Leadloy steel, until we explain that we want to try materials and methods which closely resemble what the 1860s ordinance designers and artillerymen used first. The closest thing we have found to the milled base wrought iron bolts (expanding skirt type) that the Confederate Army and Navy used, is the ledloy bolts that we make. We have shot our company's 100 Pdr. Parrott Rifle 170 times now and we are not seeing any barrel wear at all, even in the area of the bore where the skirt expands.

Thanks for your concern,

Mike and Tracy
 

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Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

You seem to be on top of it then. I'd hate to see something as unique and expensive as that bbl damaged.

You might consider making the sabots of bearing bronze rather than brass. Bronze would be less likely to foul the bore. Most types of brass tend to gall to steel under high pressure.

One more thing - Couldn't you just pin the sabot to the projectile and have the same function as that time-consuming machining at the interface?
 

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Discussion Starter · #18 ·
Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

Modern artillery projectiles use a bourrelet band at the leading edge of the cylindrical portion of the shell, this rides the bore and centers the projectile. These shells are usually made from a forging or casting and are fairly hard. 50 cal. BMG target shooter have used machined solid leaded steel or bronze projectiles in an effort to get long range accuracy before good jacketed bullets arrived on the scene. Modern military rifle ammunition has used steel jackets on bullets for years, I believe Norma uses steel jackets in their commercial ammo, this seems to have little effect on barrel life. Most of the wear on the rifling is from the hot gases and unburned powder grains moving down the bore at very high velocity or from cleaning. Black powder muzzle loaders don't really have a big problem with hot gases or powder grains, cleaning and loading will wear out the critical muzzle area of the barrel long before any ill effects are caused by the leaded steel skirt on our projectiles.

About sabots, we have not fired a projectile with a sabot as of yet, all have had a skirt machined into the base of the bullet. We will be trying a sabot in the future, this will consist of a Mullane type sabot, made of brass, copper, bronze, lead, zinc that is pinned or ratcheted and screwed to the base of the bullet. These will not be generally used as they are difficult to manufacture but we will at least fire a few for an experiment. We appreciate your comments Vicktor3.


Regards, Mike
 

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Discussion Starter · #20 ·
Re: Peek at the Design Process of Our 7" Treble-Banded Brooke Rifle

Dominic, nice to hear from you. You know what they say,"Imitation is the sincerest form of flattery". Just wanted to let you know that both Mike and I are pleased that you made a good looking front-pintle, Parrott 100pr. Do you know how far it recoils yet? Are the carriage wheels always engaged (supporting) the carriage or not?

To answer your question, we went to the big red book, The Big Guns by Olmstead, Stark and Tucker. There were 50, 6.4" rifles built; 10 survive. There were 104, 7" rifles built and 10 survive. There were 4, 8" rifles built and none survive. There were 12, 10" smoothbores built and 2 survive. There were 14, 11" smoothbores built and 1 survives today. Hope that helps you. A heavy concentration of these survivors is at the Washington Navy Yard and most of the rest we have found in 6 southern states. I counted these up really fast and could be off by one or two.

Regards,

Tracy and Mike
 
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