Canadian Airgun Forum

So I now have an adapter to tether my 1077 to a regulated to 850psi bottle, which I did. topic74188-390.html After 5 days with the rifle connected to the bottle, I saw no pressure drop on the tank's gauge, so no leaks, good starting point. I first dry-fired the rifle (no pellets), I heard a rather weak report, much less noisy than with CO2. I then loaded a magazine with JSB RS Exact 7.33gr, inserted it in the rifle and fired toward my backstop. I got an even weaker report, and no impact on the backstop, the pellet didn't even completely exit the mag!

OK, so I guess some tuning is in order. I don't remember exactly the size of the valve, but I'm wondering if its internal volume could be so small that it limits power A LOT on HPA. Or maybe the valve is locking up. Or maybe it could also be that missing seal in the ''detent'', as seen in this video: https://www.youtube.com/watch?v=oBhYc3NQXeE Or a combination of many factors.

I'll chrony the rifle with a CO2 cartridge and different weight pellets to get a good idea, and then re-try on HPA to see. If it still doesn't shoot, I'll take it apart and see what have to be done to get it to shoot at the same velocity I get on CO2. Meanwhile, ideas, comments and suggestions are welcomed.

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If everything's so lovely yeah, then why don't I, why don't I, why don't I, why don't I feel lovely?

Sounding an awful lot like valve lock to me. Would suggest verifying the output pressure of your regulator first.

Just my .02

Al

I'm sure your comment is worth way more than .02$ Al, thanks!

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If everything's so lovely yeah, then why don't I, why don't I, why don't I, why don't I feel lovely?

I tethered the rifle to my other regulated bottle, even before trying with a CO2 cart. And it's shooting, but rather weak @ a best of 318 fps. Will try with CO2 and chrony it next. When that is done , I want to open the rifle and have a good look at the complete gas path, just to see

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If everything's so lovely yeah, then why don't I, why don't I, why don't I, why don't I feel lovely?

You likely know more than me but...… I see Ebay they sell kinda rods that go in and screw on to where the chamber is. Rod looks to press up against the seal inside then quick connect on outside with cap. But they are $60. That's what I did not understand if you could just hookup like an older model QB78 or you had to have that extension to press on the seal at the back of chamber. CHEERS!

https://www.ebay.ca/itm/POWERLET-ELIMIN ... SwcndZswM0

I am using something very similar, I made one in stainless steel. It replaces the CO2 cart and end-cap, and has a male QD fitting. Happy to say that fit is perfect and it doesn't leak . Yes it does press on a seal on the face of the valve in the 1077, it's made the same way as a 2240. The valve itself is not sealed in the tube like on a QB78, so you could not pressurize the tube, and it's not designed for that, so I guess it wouldn't be safe either . Interestingly, by using a shorter tube between the two end-pieces, I could use my adapter on a 2240 (the threads are the same for the end cap). No need to do any mod to the rifle to use the adapter, and you can use CO2 cart again when you want. If you use this adapter with bulk-fill CO2, it's a plug-and-play thing. With HPA, some tuning looks to be in order for the rifle to perform well. Hope that answers some of your questions .

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If everything's so lovely yeah, then why don't I, why don't I, why don't I, why don't I feel lovely?

Thank you for clearing that up airmec. Answered my questions well. CHEERS!

Well this morning I did the detent mod, as described in the video I linked in my first post. I had an Oring and a spring the right size. Result: no gains in fps, still in the low 300s with HPA. Original spring is about 0.370'' in length uncompressed, with a 0.015'' wire. I used a spring from a sliding guide for a bifold door, it has 0.026'' wire diameter, and cut it to about 0.500'' in length. The Oring is a metric one, 5x9x2mm.

Next I'll try to add weight to the hammer (it's 43.6 grams stock), and have a look inside the valve to see if I can add some volume.

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If everything's so lovely yeah, then why don't I, why don't I, why don't I, why don't I feel lovely?

At last, some success! I took the valve apart, and saw that the valve spring has as big a wire diameter as the spring in the 13xx/22xx valves, in other words, rather heavy. I replaced it with another, lighter spring, put it back together and checked the chrony results. It's now shooting in the low 400s, that's roughly 100 more fps just with the spring change in the valve (again, on HPA). I'll dig into it a bit more, I hope to make it shoot in the mid-400s. I didn't measure the new spring, will give the dimensions in the next post.

Edit: No way to remove material on the inside of the valve, it's already rather thin, and made from some zinc casting I think. I don't want to risk blowing it up, so I left it alone.

Edit 2: Picture of the replacement valve spring, the original has a 0.042'' wire diameter, and is 0.833'' in length uncompressed. The new spring has a 0.024'' wire diameter, and is 0.750'' in length uncompressed.

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If everything's so lovely yeah, then why don't I, why don't I, why don't I, why don't I feel lovely?

So I took the rifle apart again, and noticed the hole in the detent is small compared to the hole in the valve stem, it was 0.086''. I redrilled it to 2.5mm (0.098''), this made a BIG difference. I tested it again with the JSB Exact RS 7.33 grains, velocity went from 402 to 467 fps (highest reading), better than I hoped.

I can say this is a completed project, and that it wasn't too hard. While browsing the net, I saw a lot of comments saying that HPA conversion for the 1077 is a difficult task, often hampered by leaks and small volume of the valve. Going step by step was a good way to proceed, it permitted me to gradually improve on the rifle's output, while eliminating variables. I'm satisfied with these results, I don't think I could ask for more

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If everything's so lovely yeah, then why don't I, why don't I, why don't I, why don't I feel lovely?

Good job, thanks for sharing your project progress with us all =)

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Thanks Wes . You know you're partly responsible for that

I'll see how I can improve the trigger, will post back when I'll have results, probably make a new topic.

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If everything's so lovely yeah, then why don't I, why don't I, why don't I, why don't I feel lovely?

Glad to be of service =)
It's wonderful you can make your own parts, very cool, I look forward to learning how to use my lathe as well =)

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Oh you have a lathe now? That's nice! What brand/model? Be aware though that it's a rabbit hole as deep, or deeper, as airguns

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If everything's so lovely yeah, then why don't I, why don't I, why don't I, why don't I feel lovely?

Thanks yeah hey! I just haven't had time to really try it out. I bought the wrong size center for it and still need to get another.
It's a force international or something like that. A mini lathe, 7" if I remember right, bought it off a really great fellow Ron, in Alberta west of Edmonton. =)



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