Log in

View Full Version : BP blasting cap


Wiltshire
January 16th, 2007, 02:01 AM
If I were to take a copper tube 2 inches long with two end caps and filled it with BP and detonated it with nichrome wire, would it have enough force to detonate Ammonium nitrate?

mil&co
January 16th, 2007, 02:56 AM
Two points:

1.BP doesn't detonate.

2.Ammonium nitrate (even sensitized with FO) won't detonate from just a primer, you'd need a real blasting cap (AP/SA/HMTD/MF/LA/whatever) supported by a strong booster (I think APAN or ANNM are best suited for you).

Gerbil
January 16th, 2007, 06:46 AM
I'm going to be nice, and say NO!

Do some research.

*edit* Just to clarify, you'll decapitate yourself before you get anywhere near detonating AN.

Ekilo
January 16th, 2007, 12:29 PM
No. BP does not have the "speed" you are looking for. There may be a way to do it with BP but I don't have the knowledge. Try searching the forums for homemade blasting caps.

controlledexplosion
January 18th, 2007, 07:08 PM
Try using ANFO with the addition of finely ground graphite, this stabilizes the compound and due to carbons reactivity often increases speed of ignition.

knowledgehungry
January 18th, 2007, 11:35 PM
Not enough to be set off with BP. Trust me.

Sausagemit
January 19th, 2007, 01:00 AM
While were on the subject, does anybody know if AN mixed with pyro AL (search tannerite on RogueSci for reference) shot by a high powered rifle is enough to detonate ANFO with a ANNM booster?

Because I'm not really into the whole making a blasting cap idea.

Grapes Of Wraith
January 19th, 2007, 01:43 AM
I think that it would be feasible, but Wait.... if you have access to a high powered rifle why not just make a "ghetto" blasting cap from one of the bullets?

DMSOnMyVeins
January 19th, 2007, 04:03 AM
Is this a newb question and answer topic?

nbk2000
January 19th, 2007, 06:58 AM
Well, the question is in the WC, so it's permitted, though we always encourage n00b's to Use The Fuckin' Search Engine (UTFSE) before posting. :)

Lada
March 21st, 2007, 04:24 AM
I think that it would be feasible, but Wait.... if you have access to a high powered rifle why not just make a "ghetto" blasting cap from one of the bullets?


I too have access to rifle ammo. Sorry if this is a noob question, but what exactly is a "ghetto" cap? First post btw.

NUKE(slo)
March 24th, 2007, 06:38 AM
My friend detonated PETN with BP blasting cap (sometimes work sometimes don't) but it's much more reliable to use some real initiating stuff.

tomu
March 24th, 2007, 07:33 AM
My friend detonated PETN with BP blasting cap (sometimes work sometimes don't) ...

PETN is pretty sensitive stuff especially if it's powdered and at low density (not pressed) and not phlegmatized with oil or wax.

If he is really clever he puts some powdered PETN into the BP charge of his cracker cap. Which will give his "blasting cap" the whoomph he needs for good results.

Rbick
March 25th, 2007, 01:29 AM
A ghetto cap is one made from the expended cartridge of the rifle. You just fill and press it with a primary like lead azide or AP, stick a fuse in it and crimp it. It'll throw out killer shrapnel though, so be careful :eek:

But I think the highest VoD you'll get with BP is like 400 m/sec confined, which won't even come close to detonating ANFO, even if it is activated and sensitized with AL powder or MnO2.

The idea with the ANNM booster and the high powdered rifle would probably work, you just have to hit the cap, which would probably be small. A rifle round striking an AP cap would definatley set it off. Sounds fun, 'cause you'll know if you hit your target for sure :)

LibertyOrDeath
March 26th, 2007, 09:47 AM
I've searched on the topic of using a steel pipe bomb containing a low explosive like BP for use as a detonator for ANFO, and people seem to agree that it won't work. I hope this doesn't sound k3wlish, but I find that a bit surprising, even though I don't doubt the experiences of others. The Unabomber made crude pipe bombs using mere match heads as a filler, and those were powerful enough to kill and maim people. (Granted that shrapnel rather than pure explosive overpressure was probably the reason for this.)

Of course I can see BP or smokeless powder lacking effectiveness when confined in a weak container. It simply deflagrates or, at most, makes a little "pop" as the confinement ruptures. But I used to make simple pipe bombs as a kid using nothing more than Bullseye pistol powder as a filler and a simple Visco-type fuse ignitor. They were capable of cutting through a stop sign post. I did, however, optimize those crude devices through some experimentation:

-- Bullseye pistol powder was used, as pistol powder has a higher burn rate than rifle powder.

-- The pipe was always steel with two screw-on endcaps. It had a relatively high ratio of cross-sectional area to length (e.g., 3" wide by 5" long) in order to get higher rate of burning through the pipe length. The goal was to get as much powder to burn as possible before the pipe ruptured. Long, skinny pipes often failed to explode with much force.

-- The fuse would go into a hole drilled in the center of one end cap, then around the side of some cotton wadding that had been packed between the powder and the endcap. That was to help prevent gas leakage through the fuse hole after the fuse had burned into the pipe. (This step seemed to make quite a difference. When simple match heads were used as the pipe filler on occasion, the wadding often made the difference between the thing exploding or just fizzling.)

So anyway, if I hadn't heard otherwise from people here, I would have fully expected a fairly large "Bullseye" pipe bomb made in the above way to be enough to detonate ANFO.

Thanks for tolerating this stroll down memory lane... :o

tomu
March 26th, 2007, 11:32 AM
@LibertyorDeath:

If you would have used a blasting cap instead of a visco fuse the Bullseye Powder would have most likely detonated (shockwave) and not just deflagrated (overpressure). Then such a device could be used as a booster charge for ANFO.

LibertyOrDeath
March 26th, 2007, 12:02 PM
Tomu: Yup, no doubt that using a blasting cap in conjuction with a low explosive filler in a pipe bomb greatly increases the velocity of the explosion. The blasting cap goes off, igniting all the low explosive nearly simultaneously, so the pressure spike inside the pipe is a lot higher and sharper. I think I remember reading exact figures on the explosion velocity difference somewhere, but I can't recall where. I'll do some searching and post the numbers if I find them.

EDIT: Well, I found the figures, but they were in "Kitchen Improvised Blasting Caps," which for all I know is not a reliable source. Anyway, for whatever it's worth, here's the quote:

Many people with whom I have conversed, have mentioned pipe bombs that are made by filling a pipe with either black powder or smokeless powder. These pipe bombs are poor for fragmentation due to the actual deflagration nature of this type ordinance. Deflagration is the simple burning of a propellant or explosive. This will generate pressure great enough to rupture the container (pipe) and no more. 2" schedule 40 pipe will rupture at approximately 7144 P.S.I. If black powder or smokeless powder is being used, this is the maximum pressure a pipe bomb would generate. If this same pipe were filled with powdered ammonium nitrate-fuel oil explosive and detonated with a blasting cap with an approximate pressure of detonation of 600,000 P.S.I. plus. This same set up (cap initiated) with "Bullseye" brand smokeless powder from Hercules Inc. Wilmington Delaware as a pipe filler with a blasting cap will generate approximately 2,000,000 P.S.I. plus detonation pressure. This amounts to an 8300% and 28000% increase over deflagration respectively. As these figures prove, true detonation is awesome and an unbelievable increase over simple propellant deflagration explosive fillers.I don't know if those numbers are accurate. In particular, I tend to question whether the figure of 7144 PSI is high enough, as the pressure needed to make a pipe merely crack and that needed to make it explode into tiny fragments (which happens even without a blasting cap) are certainly not the same. If the burn rate is high enough without a cap, it's conceivable that the pressure inside the pipe could overshoot 7144 PSI considerably prior to the fragmentation of the pipe. But in any case, there's little doubt that a blasting cap makes a huge difference.

nbk2000
March 26th, 2007, 08:56 PM
Bullseye powder is nitrocellulose blended with nitroglycerin.

If ignited by flame, it'll cause a rupture in a pipe-bomb through overpressure as it'll burn like BP.

If shocked by a detonator, it'll detonate like TNT, and shatter the pipe through shock.

ANFO is rather inert, and so using a fuse-ignited pipe-bomb would be pointless. Only if you used a detonator would it then have enough explosive impulse to shock the ANFO into detonating.

Cobalt.45
March 29th, 2007, 11:23 PM
Bullseye powder is nitrocellulose blended with nitroglycerin.

If ignited by flame, it'll cause a rupture in a pipe-bomb through overpressure as it'll burn like BP.

If shocked by a detonator, it'll detonate like TNT, and shatter the pipe through shock.Bullseye is said to be 40% nitroglycerin so calculate the quantity needed accordingly.