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Old 07-07-2019, 02:41 PM   #1 (permalink)
jun
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Open bolt pneu-cocker

How feasible would it be to have the trigger just actuate the 3-way and have a cam in the frame attached to the pump arm (like an auto trigger) drop the sear when the bolt is nearly closed?

Benefits would be trigger pull would be light as you’re not fighting the main spring and you can overbore being open bolt.

I don’t have the know how or equipment to pull this off but how sound is the idea?
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Old 07-07-2019, 03:42 PM   #2 (permalink)
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I think you'd need the bolt and hammer locked together to make it open bolt, and then you've just made a Spyder that uses a ram to recock instead of blowback. So, a Timmy, basically.
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Old 07-07-2019, 04:03 PM   #3 (permalink)
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I think you'd need the bolt and hammer locked together to make it open bolt, and then you've just made a Spyder that uses a ram to recock instead of blowback. So, a Timmy, basically.
You wouldn’t need to lock the bolt and hammer together though. You also wouldn’t want to do that as it ties the valve dwell to the trigger pull. The way I have it described keeps the hammer and main spring controlling the valve dwell.

The timing of the hammer release would be exactly the same as timing a pump autotrigger.

You also just swap the 3-way hoses to make it open bolt.

Last edited by jun; 07-07-2019 at 04:06 PM.
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Old 07-07-2019, 04:10 PM   #4 (permalink)
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Old 07-07-2019, 07:15 PM   #5 (permalink)
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You wouldn’t need to lock the bolt and hammer together though. You also wouldn’t want to do that as it ties the valve dwell to the trigger pull. The way I have it described keeps the hammer and main spring controlling the valve dwell.

The timing of the hammer release would be exactly the same as timing a pump autotrigger.

You also just swap the 3-way hoses to make it open bolt.

Yes, you can swap 3way hoses and adjust the sear to make it open bolt. The problem is the sear starts lowering as soon as the trigger starts moving. You'd need a custom frame setup and some creative way to separate the 3way/trigger action from the sear action... they're too closely linked in a conventional setup.

I'm sure there's a way, here's hoping you can figure it out.
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Old 07-07-2019, 09:05 PM   #6 (permalink)
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Yes, you can swap 3way hoses and adjust the sear to make it open bolt. The problem is the sear starts lowering as soon as the trigger starts moving. You'd need a custom frame setup and some creative way to separate the 3way/trigger action from the sear action... they're too closely linked in a conventional setup.

I'm sure there's a way, here's hoping you can figure it out.
You’re correct, you’d need to machine the trigger to not interact with the sear. It’s definitely not a small custom job. Would require a bit of fabrication.

Last edited by jun; 07-07-2019 at 09:29 PM.
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Old 07-07-2019, 10:20 PM   #7 (permalink)
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You’re correct, you’d need to machine the trigger to not interact with the sear. It’s definitely not a small custom job. Would require a bit of fabrication.
So basically... like a Trilogy SF frame? You might be able to adapt it to your idea.
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And God turned to Gabriel and said: “I shall create a land called Canada of outstanding natural beauty, with majestic mountains soaring with eagles, sparkling lakes abundant with bass and trout, forests full of elk and moose, and rivers stocked with salmon. I shall make the land rich in oil so the inhabitants prosper and call them Canadians, and they shall be praised as the friendliest of all people.”

“But Lord,” asked Gabriel, “Is this not too generous to these Canadians?”

And God replied, “Just wait and see the neighbors I shall inflict upon them.”

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Old 07-15-2019, 01:10 AM   #8 (permalink)
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Yes, you can swap 3way hoses and adjust the sear to make it open bolt. The problem is the sear starts lowering as soon as the trigger starts moving. You'd need a custom frame setup and some creative way to separate the 3way/trigger action from the sear action... they're too closely linked in a conventional setup.

I'm sure there's a way, here's hoping you can figure it out.
Sear movement is no problem. You just adjust the hammer lug so the release point is late and the 3 way so the recock, or in this case bolt forward, is early.

There was a guy who used a pmr frame and eblade front noid who made this by making a custom shorter cocking rod that he bolted fast to the back block with 2 washers and nuts. The lpr was tuned so that it couldn't open the valve when sitting forward so that the valve wasn't open the whole time the bolt was forward. It took momentum of the hammer to crack the valve open which made it much more consistent and efficient.
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Old 07-15-2019, 01:12 AM   #9 (permalink)
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So basically... like a Trilogy SF frame? You might be able to adapt it to your idea.
SF frame has the trigger separate yes but 3way and sear are still linked. No different than a normal frame in that regard.
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Old 07-23-2019, 02:11 AM   #10 (permalink)
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Think about a pneumatic assisted pump gun, but with an autotrigger. You hold down the trigger and fire the gun with the pump handle. Only because it’s pneumatic assisted, the stroke is easy.

Now apply that concept here with a few modifications. Instead of the pump handle moving the 3-way, it’s the trigger. The trigger is totally disconnected from the sear, the only thing moving the sear would be a modified autotrigger cam pushing on some sort of trigger plate to drop the sear.

Nothing like a select fire frame.

I’ll sketch out a diagram.

Last edited by jun; 07-23-2019 at 02:14 AM.
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