Let's Build an Airgun

A place to share your projects, technical advice. and tutorials
Adam77K
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Re: Let's Build an Airgun

Post by Adam77K » Fri Jan 03, 2014 1:27 pm

savantguarde wrote:Wouldnt a single stroke Pneumatic be simpler? I do enjoy my daisy 717's (Although they will soon be getting sold) and they are super super simple. You could even use something like the daisy valve / barrel as a basis and build up a pistol from that? 18 dollars for a barrel / valve assembly or even the lothar walther barrel / valve from the 747 (45 dollars) .
Reading the first page this was exactly my thought: SSP. I hadn't thought of Daisy specifically, but there's no reason why not. I'd love something like an affordable Feinwerkbau 103.

What is the goal of this: a brand new unique pistol or a modern replication of a classic such as the Mod.5?

As to the legal aspects. I believe it is legal for a private individual to build a sub legal limit airgun for their own use, and possibly for others, but as soon as money starts changing hands then it becomes trade or business and VCRA applies, i.e. the individual needs to be an RFD. It may be ok if the money is changing hands only to cover costs, but it would be open to interpretation and I wouldn't want to be a test case.

Our esteemed Mr Hulme is now an RFD, so may be a source of valuable advice.

P.S. This no doubt deviates hugely from you guys' design goals but if I was coming up with it I would design it to be also usable for pistol FT, so ideally 4 ft.lbs minimum and facility for fitting optics. I'd certainly be interested in a SSP with these criteria. :dance:

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Tank
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Re: Let's Build an Airgun

Post by Tank » Fri Jan 03, 2014 1:33 pm

Using a ready made valve is certainly something that should be considered, if, for no other reason, parts will be readily available at Service time. It makes very good sense.
As Phil has indicated, CO2 is a very good option. The Czech manufacturers of Tau and Brno pistols didn't just wake up one morning and say "let's build a CO2 pistol that would be a great Target tool". No, that was by design. One of the most modified and customised pistols around is the Crosman 2240/2250 and the valve from that pistol is simplicity in itself.
I see no point in re-inventing the wheel.
graham.
I’m going off to go find myself. If I’m not back by the time I return, keep me here.

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Tank
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Re: Let's Build an Airgun

Post by Tank » Fri Jan 03, 2014 1:36 pm

But as Adam has indicated, the Feinwerkbau 103 is a terrific gun and my own Walther LPM1 is one of my favourites. I actually own a Feinwerkbau 103, just the owner of that particular pistol hasn't given it to me yet! Might be because he is still using it :mrgreen:

The only way to get a gun up to FT spec easily is PCP or CO2.
graham.
I’m going off to go find myself. If I’m not back by the time I return, keep me here.

Adam77K
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Re: Let's Build an Airgun

Post by Adam77K » Fri Jan 03, 2014 2:26 pm

Oh wow! The Walther LPM-1 is new one on me so I just googled it and found the bobsairguns page! :drool:
Is that one yours Graham?

My wish list just expanded by 1.

savantguarde
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Re: Let's Build an Airgun

Post by savantguarde » Fri Jan 03, 2014 3:44 pm

So is this to be a silhouette gun or for paper punching? I just love ssp's so simple. The fwb 103 is pretty much the pinnacle of a muscle power pistol. The lpm 1 is no slouch either. I would love to know some better tech specs on them such as what the actuall cc they compress is.

Adam77K
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Re: Let's Build an Airgun

Post by Adam77K » Fri Jan 03, 2014 4:12 pm

savantguarde wrote:So is this to be a silhouette gun or for paper punching? I just love ssp's so simple. The fwb 103 is pretty much the pinnacle of a muscle power pistol. The lpm 1 is no slouch either. I would love to know some better tech specs on them such as what the actuall cc they compress is.
I'm assuming the latter as the core of this board is paper target focused; I was just doing a "wouldn't it be nice if...?" :) I don't want to take the project off at a tangent.

If I'm honest though the power is secondary. In NEFTA pistol FT we shoot to 25 yards but the concern is not trajectory it is just oomph to knock over the larger silhouettes (which also tend to be the longer range ones).

I too would be interested in those specs. In theory the narrower the pump cylinder the higher the pressure that can be achieved with the same force (pressure = force / area). However a narrower cylinder means smaller swept volume unless you have a long stroke. So you need a long, narrow cylinder coupled with a long lever for its mechanical advantage. To make the most of the accelerative energy in the compressed air you need a suitably long barrel, but this in turn needs plenty of swept volume to feed it. It's probably no coincidence that the more powerful SSPs resemble each other in overall form: FWB 103, Izzy 46M, Walther LPM-1. :think:

savantguarde
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Re: Let's Build an Airgun

Post by savantguarde » Fri Jan 03, 2014 4:59 pm

Sure someone that has a 103 or lpm wouldnt mind stripping it down :D no?

Adam77K
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Re: Let's Build an Airgun

Post by Adam77K » Fri Jan 03, 2014 7:41 pm

Like this?
http://www.classicapa.com/viewtopic.php?f=31&t=725" onclick="window.open(this.href);return false;
:D

savantguarde
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Re: Let's Build an Airgun

Post by savantguarde » Sun Jan 05, 2014 11:56 am

Pretty short stroke! Some nice diagrams here also http://www.shooting-ua.com/arm-books/arm_book_20.htm

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