Question about cap to nipple fit

[BCRider]

Wonderful. I feel much better about using a firm rocking push to seat the caps. Obviously under direct non impact pressure they are actually able to deform quite a bit without beng a danger.

I know that during placing the caps I was thinking "Wow, if this thing goes off my hand is all around the cylinder and there's still open nipples." I think I'll be wearing the gloves for capping from now on just in case. But at least I was thinking a bit and despite holding on around the cylinder and grip with my left hand I was careful to keep my fingers away from the front of the chambers.... still....

And... er..... just how big were these little piles of black you were setting off? It sounds like a Rite of Passage I still need to go through before I get instructions for the secret handshake.

 

[Ginormous]

And... er..... just how big were these little piles of black you were setting off?

Ohh . . . hmm, in one case, about half a freaking pound!

Typically, 10 to 50 grains will give a neat little pyro show for you friends and neighbors to ooooh and awwww at. It you really want to get fancy, draw a cool abstract shape, object or animal with a thin line of BP, and light it at dusk. You'll be the envy of everyone and near and far, and word will spread of your God-like prowess with pyrotechnics. Expect to have to show everyone your BP pistols too. Kinda goes hand in hand I think.

Secret handshake forthcoming . . .

 

[arcticap]

Voilà! Found - The Impact Sensitivity of Lead Styphnate

I search extensively to find some kind of objective measurement of the impact sensitivity of modern percussion caps.
What I finally found is this:

Based on a test using a 2 kilogram weight (4.40924524 lbs.), the impact sensitivity of lead styphnate is 3 inches.

http://www.teledynerisi.com/products/0products_8td_page02.asp

Put enough pressure on it and it will go "boom!"

 

[Ginormous]

That's seems pretty close to what I was duplicating I think with my rubber mallet / drift punch combination. Seems right on to me.

What's VERY interesting in that document you posted Arcticap, is the extreme sensitivity to static electric discharge. I assume the copper cup forming percussion primers acts as a Faraday cage to some extent for the lead styphnate. Otherwise we'd all be experiencing blistered thumbs on cold wintry days!

 

[BCRider]

Hard to say. The tin the caps come in would immediately bleed enough static to equalize your body contact with the can and by the time you get the lid open you and the caps would be at the same potential so no static sparks. Now if you shuffled across the wool carpet while messing up the cat in your arms on a dry winter day and reached for a cap in the middle of an open can of caps that could well results in another trip to the burn care folks. But if you make it a habit to close the tin between cylinders or at least bring your finger in to the side of the tin first so any sparks occur between you and the tin then all should be well. However for this same reason to do with dry winter days I'd want to be holding the gun in the other hand so any potential is likewise balanced between the gun, you and the cap in your other hand. If you moved the cap to the gun while you and the cap where at a high potential then a spark could concievably occur between the cap and the nipple. But how often would you ever try to cap the gun without it being gripped in your other hand? Yeah, I didn't think it would be too likely.

 

[mykeal]

Impact sensitivity of lead styphanate

Kudos to articap for finding and posting the Teledyne data. Superb information. That's going in my important stuff folder.

Within the context of this thread one point should be emphasized: 'impact sensitivity' implies that the force is applied in a very specific manner. It's an impact, like a hammer blow, not a push like one would use in installing a cap with a finger.The force time history is very short.

I know, that should be obvious to everyone, but it seems there's often one who doesn't get the word. I just wanted to prevent someone from misquoting articap's post by saying that it only takes 4 pounds of force to set off a cap. It takes 4 pounds accelerated over a distance of 3 inches by the force of gravity. That's an important distinction. Apologies for being pedantic.

And thanks, too, to Ginormous, for his time and expenditure of caps, and risk taking as well.

This confirms my experience (which is always a nice thing) that the risk of setting off a modern percussion cap with your thumb or a dowel while loading it on a nipple is very, very low. Still, it's best if one doesn't overdo it. The advice in the SASS policy is valuable.

 

[bonza]

Mykeal said:

I've never heard of "#55's",

The RWS #55s' are actually rifle caps & are a little longer than the #1075s'. I use the #1075s' on both rifle & handgun & they work just fine.