GTA
All Springer/NP/PCP Air Gun Discussion General => "Bob and Lloyds Workshop" => Topic started by: SpiralGroove on October 24, 2019, 08:35:55 AM
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Hey Bob or Guys,
Going back to re-visit my roots by doing a QB78 HPA conversion. Have done all the Ninja bottle set-up stuff, Maxi valve and RVA, but was thinking I would add a simple, but efficient version of Bob's SSG design.
I know the 47 page thread exists, but just looking for a basic prototype to copy and save time.
Also, since the SSG idea came out of a RVA design, I assume the SSG allows for RVA adjustments too - right?
Any help would be appreciated ;).
Kirk
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RVA .. only when conversion becomes a cock on open IIRC ???
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RVA .. only when conversion becomes a cock on open IIRC ???
Scott,
The rva I did with a twin spring setup retained cock on close and was externally adjustable without disassembly. I'm sure it isn't as efficient as a SSG, but it should be more so than a single spring with more preload.
Thanks.
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RVA .. only when conversion becomes a cock on open IIRC ???
Scott,
The rva I did with a twin spring setup retained cock on close and was externally adjustable without disassembly. I'm sure it isn't as efficient as a SSG, but it should be more so than a single spring with more preload.
Thanks.
OP did make the statement "SSG" thus my statement.
When I did my QB making up a complete MDS nylon hammer / SSG combo it remained Cock on Close. Due to the screw that stops the spring, it extends rearward as action is cocked.
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RVA .. only when conversion becomes a cock on open IIRC ???
Scott,
The rva I did with a twin spring setup retained cock on close and was externally adjustable without disassembly. I'm sure it isn't as efficient as a SSG, but it should be more so than a single spring with more preload.
Thanks.
OP did make the statement "SSG" thus my statement.
When I did my QB making up a complete MDS nylon hammer / SSG combo it remained Cock on Close. Due to the screw that stops the spring, it extends rearward as action is cocked.
Those parts look super. What did the rear plug look like to provide access to the adjustment? I assume that the preload is fixed and the adjustment is changing the air gap correct?
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My original SSG for a QB is here.... Reply #66....
https://www.gatewaytoairguns.org/GTA/index.php?topic=102095.60 (https://www.gatewaytoairguns.org/GTA/index.php?topic=102095.60)
Not simple, but it works well.... You could probably do a "cartridge type" (preload adjustment inside) for a cock on open system where the gap was adjusted by an off-center screw in the end cap....
Bob
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My original SSG for a QB is here.... Reply #66....
https://www.gatewaytoairguns.org/GTA/index.php?topic=102095.60 (https://www.gatewaytoairguns.org/GTA/index.php?topic=102095.60)
Not simple, but it works well.... You could probably do a "cartridge type" (preload adjustment inside) for a cock on open system where the gap was adjusted by an off-center screw in the end cap....
Bob
Yeah Bob,
Last night I saw your original model posted in post #66, but (sorry) was hoping for one less bulky ::). I had assumed most SSG designs included the RVA mod. and were "cock on opening" like all my prior RVA's. Let me find the cartridge style SSG you have suggested and see how it would work.
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I used a Mellonair RVA to implement my SSG on my 2240. It did have a 3/8 x 24 threads per inch adjuster. I removed the adjuster and bought a long brake line connector and some small bolts from LHS ( local hardware store ).
The brake line connector is also 3/8 x 24 tpi, and it has a 1/4 inch hole in it.
I don't know the dimensions of the QB, but if it's the same as a 2240 or Crosman pumper then that would be the easy way.
The nest part is that the spring and guide are smaller than 3/8 so it can be removed without disassembling the whole thing.
HTH.
Hunter
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https://www.gatewaytoairguns.org/GTA/index.php?topic=102095.860 (https://www.gatewaytoairguns.org/GTA/index.php?topic=102095.860) …. Reply #872 …. That is what I meant by a "Cartridge style" SSG....
Bob
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When I first built my QB79 for pistol field target I modified the hammer to have a recessed shoulder. And then built the SSG into the spring guide by using1/4" of the existing stem and drilling and tapping for a 6-32 screw.
Cut the screw to length, heat shrinked the threads and slipped a smooth piece of aluminum or brass pipe over it. I made a stopper at the head of the screw, towards the hammer, and then had a donut that retained the spring, fit the I'd of the hammers shoulder and slipped easily along the od of the brass tubing. And it worked really really good.
Since I have made a Nylon/ PEEK hammer with a brass cylinder inside to make it weigh 20 grams updated to cock on open, and a different SSG style.
This pistol is achieved a perfect 300% for the national limited pistol GP title. These platforms are very capable, just not super easy to tune without custom parts.
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Cameron, that looks like a very good way to make an SSG for a QB.... The only comment I have is that with HPA (and hence more pressure than CO2) you could run into problems because there is very little room for the spring.... That can lead to having to use quite a heavy spring to open the valve at higher pressures....
That is one of the problems in making a simple SSG on a QB.... getting enough room for a long enough spring and/or travel for the guide stem of the SSG.... This is because in stock form, there is a bolt through the middle of the end cap, which is why I went the convoluted route I took on my QB....
Bob
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Cameron, that looks like a very good way to make an SSG for a QB.... The only comment I have is that with HPA (and hence more pressure than CO2) you could run into problems because there is very little room for the spring.... That can lead to having to use quite a heavy spring to open the valve at higher pressures....
That is one of the problems in making a simple SSG on a QB.... getting enough room for a long enough spring and/or travel for the guide stem of the SSG.... This is because in stock form, there is a bolt through the middle of the end cap, which is why I went the convoluted route I took on my QB....
Bob
You are right Bob,
You have very minimal spting to get the hammer acceleration up so you use a heavier spring. With valve porting and other work it makes 12fpe with my ultra light hammer using an 8.5#/ in spring and that is with 1/4" + free flight!
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Thanks Guys for everything ;); I'll see what I can figure out.
Just trying to get around 80+ shots per fill instead of 70+ using CPM at about 880 fps.
Kirk