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Has anyone ever done a RL crossbow-like prime?


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#1 Bryansuh

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Posted 16 February 2017 - 09:11 AM

I DID search for crossbow. Just a disclaimer. I found one similar, (kinda) the 'has anyone made a crossbow with working arms' thread.

So. The basically has anyone made a blaster that requires you to put one of the ends down on the ground and use your entire body to prime?

The only reason for this is because at high draw weights, it gets hard to prime with your arms alone. You could put like 130lbs of spring power and prime it relatively easily. Compare THAT to a more 'normal' blaster.

Of course with that much power most/all of the parts have to be metal. And the barrel has to be pretty dang long for efficiency. Also maybe custom darts like stefans which can handle the acceleration.

It doesn't have to look like a crossbow, just the priming basics have to be similar to a crossbow.

PS. I know it's not war practical. It might not even be legal in some states or counties. But it's a cool idea
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#2 CaptainSlug

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Posted 16 February 2017 - 10:19 AM

No, because as you already know a draw weight that high wouldn't be useful for a war. And most of the innovation here is driven by the desire to USE these at a war.

 

There are plenty of homemade blasters that use bow arms instead of springs.

 

1/2" Coupler Bow Conversion
SNAP-7 Microbow
The Autobow Mk II
AABow
SNAP-7.5 Micro Crossbow
SNAP-7.5 Pump Crossbow
PACBow
Bowpup
BullPac


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The little critters of nature, they don't know that they're ugly. That's very funny, a fly marrying a bumble bee. I told you I'd shoot, but you didn't believe me. Why didn't you believe me?

#3 Bryansuh

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Posted 16 February 2017 - 06:45 PM

Aww. Thanks anyway.
But think about it.
57lb= 200fps. So 130=200×2^1/2= 300fps.

I saw a bike pump Longshot that did 400fps. So maybe some one, somewhere made this....
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#4 CaptainSlug

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Posted 17 February 2017 - 10:20 AM

I've made several blasters that hit 200+ fps with only a K25, which has a maximum compressed load of 35 pounds. A K26 which tops out a few pounds higher can get a few dozen more fps.

 

fps doesn't scale in a linear fashion with compression load. There are plenty of other factors involved such as barrel length, plunger volume, plunger mass, plunger peak velocity, and air restriction in the output (or back end venting) of the plunger tube.

 

The nice thing about bow arms is similar to the benefits of using surgical tubing. Both mean that you can make adjustments to the tension setting, which allows you to adjust your maximum compressed load easily.


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The little critters of nature, they don't know that they're ugly. That's very funny, a fly marrying a bumble bee. I told you I'd shoot, but you didn't believe me. Why didn't you believe me?


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