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Comparing a pistol cross bow to an airgun spring

Posted: Wed Aug 04, 2010 2:33 pm
by qwerty
I have been looking at the airgun crossbow idea and thought that the cheap 50lbs pistol crossbows would be perfect for the job but how would these compare to a spring from an air rifle that fires... ummm.... around 600 fps at .177 caliber?
Would it be much stronger than a crossbow or weaker? i just don't know as i haven't had any experience with commercial springers.

Thanks. Hope you can help.

Posted: Wed Aug 04, 2010 3:42 pm
by jonnyboy
Well most .177 cal springers fire around 900 fps for a medium weight pellet and cock around 25 pounds. I'm pretty sure know what your talking about with the airgun crossbow but I haven't been around lately so maybe the idea is really different but the comparing the velocity of both designs without actually building one has lots of variables.

Posted: Wed Aug 04, 2010 10:52 pm
by jackssmirkingrevenge
There's no way I could cock the spring on my HW45 manually in a direct manner similar to those cheap crossbows, and that's only doing 4.5 ft/lbs or so. I think power wouldn't be too great.

This project was pretty tough to draw and the power wasn't much better than a cheap-o airsoft spring pistol...

Posted: Thu Aug 05, 2010 2:20 am
by qwerty
Actually the 80lbs crossbow is cocked using a lever at the back like this

http://www.superbows.co.uk/Archery/Cros ... d_465.html

Thats about 40kgs if i do it manually.

Well most .177 cal springers fire around 900 fps for a medium weight pellet and cock around 25 pounds
Not neccasserily i've seen many under that.

Posted: Thu Aug 05, 2010 2:47 am
by jackssmirkingrevenge
Note that springers have a much shorter stroke than crossbows, and tend to use a wide piston. I would use a long narrow piston, and make sure that there is some sort of detent in the breech that keeps the projectile in place until sufficient pressure builds up to fire it.

Posted: Thu Aug 05, 2010 6:45 am
by Ragnarok
For this type of comparison, cocking "weight" is pretty useless without also knowing the associated draw length.

For example, my AA TX200 HC has a peak cocking force of about 40 pounds (although that can still be done with a single finger), and gets about 800 fps with an 8 grain pellet.
However, it has a very short 9.5" cocking lever and quite a short "draw length" to go with it. Which means the energy stored in the spring is fairly low.

Ultimately what that comes down to is that it's not really possible to compare without a lot more information than just draw weight.

Posted: Thu Aug 05, 2010 6:56 am
by qwerty
Ok, so i can't realy compare but do you think i should just go for it?

Posted: Thu Aug 05, 2010 10:37 am
by jackssmirkingrevenge
qwerty wrote:Ok, so i can't realy compare but do you think i should just go for it?
It will certainly be cheaper than this, why not ;) If the project doesn't work out you still have a crossbow...

Posted: Thu Aug 05, 2010 11:18 am
by qwerty
It will certainly be cheaper than this,
I still think that is one of the most ugliest guns in the world...

Posted: Thu Aug 05, 2010 11:23 am
by jackssmirkingrevenge
:shock: BLASPHEMY!!! :shock:

Looks like a 1911 on steroids, my pretty baby :)

Posted: Thu Aug 05, 2010 11:26 am
by qwerty
It's horrible. Its all big and stuff.... ughhh it's like a painball pistol-normal sized grip with a huge barrel/chamber

Posted: Thu Aug 05, 2010 11:31 am
by jackssmirkingrevenge
qwerty wrote:Its all big and stuff....
De gustibus non est disputandum, that's exactly what I like about it :)

Posted: Thu Aug 05, 2010 11:35 am
by qwerty
I hope not the same about women....

Posted: Thu Aug 05, 2010 11:37 am
by jackssmirkingrevenge
qwerty wrote:I hope not the same about women....
Quite the opposite, after a traumatic experience in my adolescent years :roll: