concrete filled projectile in a rifled cannon barrel?

[Joey V.]

Hi all,


I have a "in the works" 3" Parrott cannon 1/3ish scale ready to test fire.  This is made from a section of Bofors barrel and 4140 steel breech.  I milled out a couple of molds so far to cast rounds, one is a wad cutter type, the other is a copy of a bofors round.  Issue is the weight of the lead is too heavy.  I am loading down the bore of the gun so I made my projectiles to obtruate to grab the rifling.  anyone have any ideas if a PVC filled with concrete could be an alternative?  I will have to possibly paper patch the round to grab the rifling or see if I can leave a little PVC cup at the rear to expand into it???  Anyone have any thoughts?


Thx
J

[Double D]

Instead of lead use  Zinc.

[GGaskill]

I would certainly give the lip at the rear idea a try.  And make sure you have some method of fixing the concrete to the PVC sleeve so they remain connected.  Maybe taped over holes through the PVC so the concrete is engaging the PVC but not contacting the bore.

[Artilleryman]

There are a number of Parrott crews that are using a scaled up pellet rifle lead pellet with very good to excellent results.  In a full size Parrott (3 inch) the pellet weighs 6 lbs.

[Cannon Cocker]

Here are some pellets that I use in my 2.25" mountain rifle.  The first one that looks like an actual pellet gun pellet make the groups at the 200 yard target shown in the third picture.  With this pellet they are always this good or better, but if I go back another 25 yards it all goes to hell.  The last pellet is one that a friend shoots at longer ranges, and I have never tried.  I have good results with a different design (not pellet) for long ranges but am always looking for a better design. 

[Double D]

Now if we can find some mould make to make us some of these in 1 inch----you listening the Ed.  Cannon cocker how about some detail and close up picture as to how that mould is made!

[Cannon Cocker]

  Cannon cocker how about some detail and close up picture as to how that mould is made!

[Joey V.]

Now that looks like a great idea!  Looks like a Lyman sabot deer slug I shoot for deer hunting.  I happen to know a guy with a milling machine and a lathe...ME!    . 


Thanks guys I appreciate all the info you all share!


THX

[Double D]

Okay, Ed, there you go. Make me one for 1.000 bore!

[Joey V.]

Cocker,


Missed something you wrote.  You said at 200 yrds its a great group at 225 all goes to hell.  Same thing with the Lyman slug past 100yrds.  Lyman actually designed the slug to tumble at low velocity to have it bury into the dirt if you missed the deer for safety reasons.  I need to make one that is for a 40mm bore (Bofors) so can you tell me how long yours is measuring?  I will shrink it by length to diameter percent and give that a try.  I am also real curious as to how yours mics out agains the 12G Lyman slug??  Looks spot on.


Thx

[Articifer Tom]

Did anyone note that to lighten you hollow the base . This also allows for expandion to grab rifling .

[armorer77]

Douglas , I am slowing down , finally . This looks pretty straight forward . I will give it a shot in a month or two . Ed

[Cat Whisperer]

PVC pipe (filled with concrete) has some advantages:  VERY consitant diameters and low cost.

There may be an issue with affixing the concrete inside it, but not unsolvable.

Consider a "bourrelet" or driving band - perhaps cast from lead or zinc that would be at the base.  Perhaps cast in place, perhaps attached after casting.

[Cannon Cocker]

I'll round up the a diagram of the pellet dimensions soon.

 There is another way to make a mold which I would probably choose over the lead pellet if you're using a 1.57" Bofors barrel.  Here's a quick diagram of it, and it will work at all ranges, not just 200yrds or less.  It will work with both lead and zinc, but I would use zinc because of the weight.  Lead or zinc both shrink about 1%,  so the section that was cast in the barrel area will come right out.  I've tested this and proven it many times.  I would use this technique on the mountain rifle if the rifling was not prohibitive (saw tooth).  You will have to do a little experimenting to determine how big the engagement area (how long of a section of bore) will be because at some length it will bind up because of the gain twist.  I would cast different length plugs in the barrel section and push them through the bore to see what you can get away with.  You can pour around a piece of conduit standing in the section which makes something that looks like you would use for lapping.  This rifled plug on a conduit handle can be pushed down the bore and retracted if it binds.  Use a lot of oil too.

  You may end up being able to use something that looks like the first drawing, or be limited to something like the second. 

[Cannon Cocker]

I made a mistake in labeling the dimension of the nose.  It should say and be LAND diameter where the base of the nose meets the top of the barrel section.  Otherwise the nose would be to big.  The cast bolt will look something like this when done correctly.

[Victor3]

Here are some pellets that I use in my 2.25" mountain rifle.  The first one that looks like an actual pellet gun pellet make the groups at the 200 yard target shown in the third picture.  With this pellet they are always this good or better, but if I go back another 25 yards it all goes to hell.  The last pellet is one that a friend shoots at longer ranges, and I have never tried.  I have good results with a different design (not pellet) for long ranges but am always looking for a better design.

 What you've experienced with this style projectile is the same as folks using it in airguns have found; flat-nosed, diabolo pellets have a lousy BC. Great accuracy within a given range but useless beyond it. They're popular with paper-punchers because they make a neat hole.


 If a hemisphere is added to the front end, long range accuracy (and energy retention) improves significantly.

[Cannon Cocker]

The skirt,  although stabilizing in the same way as a badminten birdie, also contributes to the drag for long range.  If I were going for accuracy (less than 200 yards) with a smooth bore gun, I would use the pellet design.  I have recovered probably a hundred pellets and studied them for rifling engagement.  Many had NO engagement (not a single mark on the skirt) yet did not seem to affect accuracy.  I have a 2.25" smooth bore barrel (Verbruggen style) that I could confirm this with some day, but I don't think I need to after seeing so many examples. 

[Joey V.]

I grabbed a lyman slug to model after. I think if it will work great in a rifled cannon because they are awesome in a rifled shotgun!!.  I found the key to great accuracy with a muzzleloader or shotgun has a direct relationship to rate of twist and velocity.  I can shoot a heavy conical or a sabot from a fast twist muzzleloader with a large charge of powder as is recommended.  I can also shoot a patched round ball from a fast twist rifle if I cut the powder waaaay down.  Cocker, I like the conical type bullet so I will give it all a try.  I will report back on the PVC on Monday. I plan to shoot close 50 and 100yrds this weekend.
 

[Joey V.]

Range report

I fired a few different projectiles at 100 yards with very good results from a 20" section of bofors barrel the front most part.
1. Heavy cardboard tubing filled with Portland cement. The cardboard tubes where 1 1/4" x 4" long.
I mixed Portland cement very dry just enough water to cake up. I used a dowel rod of tube I.D. And packed the cement with a a 32oz hammer. To my disbelief once you pound down one end an flip it over the cement will not push all the way down the tube. I had to add from both ends and keep pounding until I filled it! The tubes where way undersized so I "patched then" with duct tape lol. They all hit in a paper plate size group 100yrds! I couldn't belive it.  I found all tubes with cement still in it though all where crumble from impact the cement stayed put without a plugged tube end.  The duct tape well it looked like the rifling ripped off a few layers as none had rifling grooves engraved. I believe the bolts caught enough spin to keep them on track at 100 yards. The tape streaked the barrel and its a pain in the butt to clean it out. Next time I will paper mâché patch the bolts and see. I expected the cardboard to obtruate but it didn't at all. Unfortunatle I can't cheaply get this cardboard tube in say 41mm diameter as it would cost $100 of dollars for a small run at the tube factory.

2. 1 1/4pvc shed 40 pipe filled with Portland cement. I had to turn down the PVC to bore diameter this was time consuming but easy on the wood lathe using a mandrel inside the pipe. Then I scored the crap out of the PVC inside with a sanding drum and 40 grit. Great accuracy and the rifling did take on these and the cement stayed put in the tubes.  I left a 1" skirt on the base for obtruate and it worked!
Now I think about it I bet the PVC is what streaked the barrel...
I fired all with 600g of cannon blk p. 
like a dumb dumb I forgot to take a pic of the fires rounds but the PVC has a lot of promise I think. I will keep up the tests and report as we go.