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I still haven't learnt...

Posted: Wed Sep 16, 2009 1:25 am
by MrCrowley
...to always use a backstop.

Some of you may have seen my 'Just Went Mach 1' thread where I posted some of videos of my hybrid. Both JSR and I noticed poor performance in penetration, he gave me some advice and today I used that advice in a very bad way.

You may remember the 4" thick piece of wood...yeah I shot through it...and my garage door :shock:

I made a far better sabot for the .303 bullet I was using, and it went straight through, clean as a whistle. I managed to hammer the hole in the garage door (see photo) a bit so it's only just noticable...not sure what I can do to make it less noticable while my parents are home and will hear me hammering on the garage door.

I blame this on JSR! :D

Anyway, here are the pictures

edit: the entry wound is bigger because the metal sabot went 3/4 way through the wood too.

Posted: Wed Sep 16, 2009 1:36 am
by jackssmirkingrevenge
HAHA!!!

I knew it had more potential than you showed in your first post :D

Excellent, kudos!

Should your parents in any way hold me liable for the damage to the garage door, might I point out that I constantly stress that the power of one's launcher should NEVER be underestimated and an adequate backstop (that isn't a row of primary school children :P) should be used ;)

Posted: Wed Sep 16, 2009 1:50 am
by MrCrowley
Should your parents in any way hold me liable for the damage to the garage door
They'll probably think you're an imaginary SuperHero I invented:

Parents: An epoxy cave in Europe?
Me: Yeah, cool huh?!

:D

I think the bullet ricocheted of the fence (it's on a 30-45 degree angle) outside after leaving the garage, then it should have gone in to some bushes...I hope :roll:

Posted: Wed Sep 16, 2009 2:00 am
by jackssmirkingrevenge
LOLOLOL :D
MrCrowley wrote:Parents: An epoxy cave in Europe?

MrC: Yeah, cool huh?!

Parents: nodding slowly while reaching for a strait jacket Yeah...

Mother: sobs inconsolably

Father: tries to conceal the fact that he is brimming with pride
We should write a spudfiles pantomime :roll: :D

Shame you don't have a video of this by the way, I don't suppose there's a chance of a repeat performance? Two blocks of wood this time though ;P

Posted: Wed Sep 16, 2009 3:05 am
by MrCrowley
jackssmirkingrevenge wrote: Shame you don't have a video of this by the way, I don't suppose there's a chance of a repeat performance? Two blocks of wood this time though ;P
I could cut it in half and put them back to back...that i'll video :P
I wonder how this compares to handguns in penetration...i'll have to wait till i get some plywood to compare with BoxoTruth.com

Posted: Wed Sep 16, 2009 3:30 am
by jackssmirkingrevenge
If I recall well the old standard of lethality for a projectile was penetration of 2.5 inches of pine board. The modern (but really quite arbitrary) NATO standard at the moment is 58 ft/lbs of energy, I think you've comfortably exceeded both ;)

If you look here there's some testing with 3/4" pine boards. A typical 9mm or 0.45" pistol round seems to penetrate around 6 inches, though since the boards are spaced you can't compare them exacty to an equivalent single thickness of wood, and of course the type of wood does make a difference. I think a chrony, balance and calculator would provide the best data to make some effective comparisons ;)

Posted: Wed Sep 16, 2009 3:40 am
by inonickname
I find that bits of wood spaced out tend to be much easier to penetrate than one thick sheet. Most likely to do with the dampening or buffering effect in thicker pieces.

Nice penetration though :wink:

Posted: Wed Sep 16, 2009 4:13 am
by POLAND_SPUD
it would be goof to find one material that is easily available everywhere and has the same properties everywhere... that would make comparing different launchers easier...

maybe ballistic gelatine?

Posted: Wed Sep 16, 2009 4:22 am
by MrCrowley
POLAND_SPUD wrote:it would be goof to find one material that is easily available everywhere and has the same properties everywhere... that would make comparing different launchers easier...

maybe ballistic gelatine?
Looks like i'm going to be stuck with this wood for now, I'd probably have to make 3 ice cream containers worth of ballistic gel and that doesn't sound like fun, let alone I can't even find gelatine at the supermarket.

I'll try putting the wood back to back tomorrow, see how it performs against 8" of wood. Anyone want to take bets? :P

Posted: Wed Sep 16, 2009 4:24 am
by POLAND_SPUD
I can't even find gelatine at the supermarket
same here... I was hoping that someone could find something else

Posted: Wed Sep 16, 2009 4:31 am
by MrCrowley
I don't think I ever understood the true power of a gun until I built this. Sure I knew they were pretty damn powerful, but I couldn't put it in to perspective. Hollywood does a great job of dampening the effect of a gun.

People probably still think they can hide behind car doors for protection :shock:

Posted: Wed Sep 16, 2009 5:15 am
by jackssmirkingrevenge
POLAND_SPUD wrote:it would be goof (good, surely) to find one material that is easily available everywhere and has the same properties everywhere... that would make comparing different launchers easier...
:idea:

DO'H!

:roll: :D
People probably still think they can hide behind car doors for protection


Enfeebled dolts... :)
Anyone want to take bets?
100 spudbucks it will make it half way through the second block - but I would *still* use another backstop behind it.

Posted: Wed Sep 16, 2009 5:51 am
by MrCrowley
but I would *still* use another backstop behind it.
Any ideas? My BoxoCrap is gone. Maybe I can find a few books, or better yet, maybe there's some sand laying around close by... :roll:

Is there a ballistic comparison between wet sand and dry sand somewhere in the dark realms of the 'net?

edit: got any ideas for tails for a .303 bullet? What I used today worked well as both sabot and 'tail' but its a one off. I need something I can keep reusing. What about a tail made from masking tape? Wrap it around the base of the bullet and then gradually off the end of the bullet in a shrinking diameter to form a tail.

Posted: Wed Sep 16, 2009 6:02 am
by jackssmirkingrevenge
One or two phonebooks should suffice.
What about a tail made from masking tape? Wrap it around the base of the bullet and then gradually off the end of the bullet in a shrinking diameter to form a tail.


I think I had suggested something similar when you first started using 303 bullets, let's face it - it's not going to be reusable :roll:

Posted: Wed Sep 16, 2009 6:05 am
by MrCrowley
let's face it - it's not going to be reusable
Sorry, I didn't mean that the tail and bullet would stay intact, I meant I can keep making the tails easily :P

Yeah you probably did suggest that earlier on, then again you've suggested half the sh|t I have done when it has come to spudguns :D