AEA HP Carbine TD/Assassin .25 cal without the moderator not cycling in semi-auto

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Sicumj said:
You have increased the gap for backpressure by eliminating the baffles. That cylinder hooked to the cycling rod can be adjusted forward or backward and slight adjustments affect action cycling. If you don't want the moderator get a 12 " shroud and cap. Pellet shop did that for me on my Backpacker 25.
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Ahhh. Makes more sense now. So there is no way to run it to be the same size as the HP SS Plus and just screw on the moderator afterwards as a per need basis, correct? So I would physically have to get a longer shroud to add the baffles in or shorten the cycling rod.
 
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I have a 12" shroud, then a Donny fl adapter right into a Sumo. Backpressure goes back through the holes in the ring on the barrel and pushes the cylinder backwards working the action. I don't know how to get yours to work without something like that. Pellet Shop may have the stuff if you want that. Or you can call those guys and see what they advise.
 
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Sicumj said:
You have increased the gap for backpressure by eliminating the baffles. That cylinder hooked to the cycling rod can be adjusted forward or backward and slight adjustments affect action cycling. If you don't want the moderator get a 12 " shroud and cap. Pellet shop did that for me on my Backpacker 25.
Click to expand...
Great tip...thanks!
So basically, If I want the shorter size to run semi auto and only use the moderator when I need to, then I should be looking at a DonnyFL can I assume?
It sold me when I saw others shoot it in semi with and without the 4" moderator...with the obvious dB difference.
Now that I think about it, when I took off the shroud to clean her, I might have made an adjustment by mistake. I'll check it out.
 
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Sicumj said:
You have increased the gap for backpressure by eliminating the baffles. That cylinder hooked to the cycling rod can be adjusted forward or backward and slight adjustments affect action cycling. If you don't want the moderator get a 12 " shroud and cap. Pellet shop did that for me on my Backpacker 25.
Click to expand...
btw...would you happen to know HOW to make those adjustments to the cylinder? I have it apart now lol
 
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You have to remove the barrel.
Remove shroud.
Remove four bolts at receiver
Pull the ring toward muzzle you just unbolted and there will be a lock nut that you loosen
Loosen Allen set screw on receiver ahead of breach on top of receiver
remove lock nut from barrel and remove, spring will come off and then cylinder is clear to screw in or out..


To reset barrel gap insert mag and screw in barrel until mag can be inserted but removes freely,.
Lock barrel in place with set screw on receiver by just snugging down,
Tighten locknut
 
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You need the 1/2 by 20 HP adapter plus a shorter shroud. I would call Bin at the Pellet shop or Utah air and ask if the shroud is available. The shroud length on my Backpacker is 12". You reuse your endcap off your original shroud to replace the adapter when you remove the moderator.

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Sicumj said:
You need the 1/2 by 20 HP adapter plus a shorter shroud. I would call Bin at the Pellet shop or Utah air and ask if the shroud is available. The shroud length on my Backpacker is 12". You reuse your endcap off your original shroud to replace the adapter when you remove the moderator.

View attachment 325644
Click to expand...
So now....when you remove the DonnyFL, does she still go in semi-auto or no?
 
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Sicumj said:
You need the 1/2 by 20 HP adapter plus a shorter shroud. I would call Bin at the Pellet shop or Utah air and ask if the shroud is available. The shroud length on my Backpacker is 12". You reuse your endcap off your original shroud to replace the adapter when you remove the moderator.

View attachment 325644
Click to expand...
Shorter shroud....10"?
Mine currently has a 12" CF shroud on it.
 
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Looks like you have what you need now. Pictures do wonders. What does the end of the shroud look like when you remove the moderator? This is mine with the moderator off. Mine came with two shroud ends. One is a thread protector that screws onto the threads on the adapter (pic 3) The other screws into the shroud if the adaptor is removed. With either installed and even with just the adaptor only (pic1) rifle should fire semi auto. Mine does.

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Ah, I see now. That's because you have the Donnie FL adapter with the Donnie FL moderator. I have an earlier model just before they stopped with the carbon fiber shroud in moderator, according to the guys at The Pellet Shop.
It seems as though I may just need the Shroud adapter. Looks like that would provide enough back pressure to cycle. Mine has too big of an opening evidently. According to those guys, it should not fire in semi-auto without the moderator

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...... actually their exact words were, "it is hit or miss if it would fire in semi-auto without the moderator", and evidently they have tried multiple times and could not recreate it 🤷

In all fairness, I am starting to believe that my hammer spring might need a little boost. That might her with just enough to get her to cycle. I know my numbers comparatively to others, are looking like 10-15 FPS less than it could be
 
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The hammer springs get week. I have mine spaced about 3/8". Velocity on mine dropped about 100 fps a while back. With this spacer its back to where it was 27 g slug at 900 fps. I think you have enough pressure with your setup.

I detuned mine some so it would not cycle so hard. I had it so light that it would not cycle without a pellet in it. Couple months later it became unreliable and didn't sound as strong. When I checked velocity it was down. That is when I realized it needed more hammer spring, I ground down A 5/16 nut and stuck it inside the stock end. Later I made some bushings on the lathe of different widths.

I would try spacers first. I polished the spring guide rod and hammer. Use a good lube and lube the cylinder inside the shroud too. Sorry to lead you astray. Pictures helped me I thought your setup was different. The hole in picture one is a bit over 3/8" looks like that is what yours is from what I can tell.

Here is the sweet spot for me on the cylinder adjustment. You can see about two threads of the rod going past the cylinder. Also this cylinder can get sticky and slow down the cycling. I like running my dry as possible.

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