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Author Topic: British wall gun, short barrel replica.  (Read 1241 times)

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Offline Third_Rail

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British wall gun, short barrel replica.
« on: March 08, 2005, 05:25:15 PM »
Hello all. I found this forum through Google, and I have to say I love it.
 
 
I'm planning on making a wall gun replica, a shoulder fired cannon of 1" bore and ~50lbs.
 
I'm going to use 2" 4140 steel, for a barrel wall thickness of .5" - question is, will this be enough??
 
I know that none of you can give me a perfect answer, being that it hasn't been machined yet. Max powder charge with pure lead ball of .98" would be 150 grains of Fg.  
 
The barrel will be 2' long, with the last 3" of the barrel un-drilled/reamed to make sure NOTHING comes back that way.  The stock will be made of white oak, and it will be quite bulky to add to a total weight (with lock) of 50+lbs, so that recoil will be manageable.
 
 
 
Any insight?
 
Thomas
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Offline GGaskill

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British wall gun, short barrel replica.
« Reply #1 on: March 08, 2005, 08:10:33 PM »
What are you going to use as the firing method?  Percussion?  Flintlock?  Matchlock/fuse?

Drilling the bore will be an interesting project.
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Offline Cat Whisperer

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British wall gun, short barrel replica.
« Reply #2 on: March 09, 2005, 01:19:29 AM »
Third_Rail -

WELCOME!

DD is the charge-meister here; perhaps he'll look up the recommended charge from the 'bible' The most-best cannoneer.

I would certainly use a coarse powder (say Cannon grade) for that barrel length.  There are formulas you can apply to measuring hoop-strength and so forth and there are folks that post here that can guide you through the process.  For me it would be guess-work.  My feeling is that 1/2 inch wall thickness is good, but it's best not to guess.  N-SSA requires 'steel' unspecified type liners of 3/8" wall thickness in the cannons used in their competition.

CJ has built a 1" bore cannon - check out the steel and the dimensions she used in the liner of her cannon (in a lengthy post much earlier here).
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Tim K                 www.GBOCANNONS.COM
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Offline Cat Whisperer

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British wall gun, short barrel replica.
« Reply #3 on: March 09, 2005, 01:21:54 AM »
SHOULDER FIRED?

Only two words in response:  SELF INFLICTED!
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Tim K                 www.GBOCANNONS.COM
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Offline Third_Rail

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British wall gun, short barrel replica.
« Reply #4 on: March 09, 2005, 02:37:26 AM »
Being a machinist by hobby, drilling a 1" bore straight and reaming it true won't be a problem for me.


Shoulder fired is right. I did some math, the recoil from a 50lb gun would be on par with an 8lb 12ga using a light 1oz load going 1000fps!


For the firing system I'll be buying either a lock casting kit and hand fitting a percussion lock, or buying a cheap percussion rifle and using the lock from that. I WON'T be using the supplied nipple, though, that I'll be turning myself.
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Offline CAV Trooper

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British wall gun, short barrel replica.
« Reply #5 on: March 09, 2005, 03:05:20 AM »
third_rail,

Welcome to the board. Unheat treated 4140 has a minimum yield strength of 60,000 psi so you should be fine with the load you propose. If the steel has been heat treated, that figure goes way up. Check your steel supplier to find out if it's been heat treated. Stronger is better.

If you can get some 1144 Stressproof, it has a yield strength of 100,000  psi without having to be heat treated.

I've fired 150gr of 2Fg in a normal sized cap & ball rifle and the recoil is less than my M1. Granted, your projectile will be more massive, but 150gr is a fairly light load for what your proposing so I don't think recoil will be much of a factor.

The NPS has a flintlock wall gun at the Castillo de San Marcos in St. Augustine, FL that is absolutely MASSIVE. Next time I'm there, I'll get some pictures and post them.
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Offline Third_Rail

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British wall gun, short barrel replica.
« Reply #6 on: March 09, 2005, 03:15:49 AM »
Massive is right. This is the short barrel replica... the next one I make will have the full length barrel.  :grin:

I'd rather make it with 4140, it's already costing quite a bit (less than buying though!)... I'll look at the 1144 prices, though.
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Offline Mike Scott

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1" bore rifle
« Reply #7 on: March 09, 2005, 04:26:28 AM »
My 4 bore (1.053") underhammer percussion rifle has a 1.5" diameter octagon barrel made of 4150 rated for 350g ffg and 4 oz round ball.  The total rifle weight  is a little light at 14 lbs.  Loads up to 150 gr of Triple 7 and patched ball are pleasant to shoot.  200-250gr is OK.  

300 grain Triple7 loads with a 4 oz ball are not very nice...
http://outcast.homeunix.org/uploads/4bore.mov

You have nothing to worry about recoil.  In fact, I would cut your planned rifle weight down to 25 lbs or so just so you can handle it better.  Especially if you are only planning to shoot light loads.
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Offline Third_Rail

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« Reply #8 on: March 09, 2005, 06:54:02 AM »
Great!! I love over engineering things. Belt and suspenders, etc. :grin:
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Offline Third_Rail

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« Reply #9 on: March 10, 2005, 06:56:06 PM »
Mike Scott, I thought of something... do you know if the barrel on your 4 bore is heat treated?
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Offline Mike Scott

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British wall gun, short barrel replica.
« Reply #10 on: March 11, 2005, 06:50:19 AM »
I don't know.  The barrel and breech plug were bought from Ed Rahyls' shop so he would certainly be able to tell you.
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Offline Third_Rail

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British wall gun, short barrel replica.
« Reply #11 on: March 11, 2005, 07:27:46 AM »
Thank you anyway, I appreciate taking the time to tell me, even though you didn't know.  :-)

Is Ed Rahyls (or is it Rahyl?) a member?


EDIT: One other question, actually. How thick is the breechplug?
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Offline Lyle

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Wall Gun
« Reply #12 on: March 11, 2005, 09:29:35 AM »
I have a 1" bore wall gun..weight is about 40 pds.  It has a swivel mount that goes into a post and that takes up the recoil for the most part.  Normal load is 240 Fg.  For a noise load only use a 35 mm film can of FFFg with a light wad of rock wool ceiling insulation.  
  The rule I use for breechplugs is minimum thread distance is 2 x the wall thickness.  Usually add a little more.  My barrel is Shelby tubing  .5" walls in breech area and for about a foot past the breech area..slightly swamped with a cannon muzzle shape.  
   Lock is a Brown Bess flint lock from Track of the Wolf. There was a rumor that the pan took more powder than a lot of  rifles.  
   The sear arm has to be extended a bit to get to the trigger. I put a roller on the sear arm..makes a lot lighter trigger pull.  
  240 grs. puts a mild dent in 3/8" mild steel.  320 grs puts a serious dent in the plate.  
   We used to shoot a match with it and it was a lot of fun.  

                                                        Lyle
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Offline Mike Scott

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British wall gun, short barrel replica.
« Reply #13 on: March 11, 2005, 10:32:09 AM »
W. E. Rayl
Box 91
Gassaway WV 26624
304-364-8269
Custom barrels,most any cal.,twist,profile etc.
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