AEA Varmint mods

[sb327]

I’m sure others have modded their AEA’s. Here’s what I’ve got going with mine.

First, the hammer spring is stiff. Not horrible but pretty stiff. This in turn makes the trigger a little heavy. So, I made a balanced valve. While I was at it, I cleaned up where the valve seats. I bored it with a 1/2” endmill till the tapered seat was gone and I could use the smallest flat poppet I could. About .312”. The balance chamber is .200”. The piston is made from titanium and floats inside the valve screw. I cut the inside of the valve screw for a snap ring. The poppet is glass filled pei.

Then I made a new hammer spring from .045” music wire. I tapped the spring retainer/stock mount 7/16” fine thread. Made an adjustment screw that is bored for the spring guide. Cut slots inside it and drilled hole in spring guide. I cut a small screwdriver slot in spring guide. A piece of wire through the hole in spring guide links it to the inside of the adjustment screw. To adjust hst, just fold stock to access the slot in the spring guide. The hammer has almost a 3/8” of free flight at lowest set point.

I cut barrel threads further forward so the barrel nut tightens against the shroud mount. Now you don’t have to take the shroud mount off to take the barrel off. More a preference than improvement.

I made a ‘bolt action only’ trigger that gets rid of the disconnect overtravel and has a sear engagement adjustment screw.

Here is a picture of the the various parts mods. I also put the original hammer spring, poppet and poppet spring in for comparison.

Dave

[sb327]

I’ve added a Sekmet gauge to the varmint. The factory gauge is a very small 8mm thread. The sekmet I have is a 1/8 bsp. Where the factory gauge screws in the frame is pressurized so I didn’t want to enlarge that hole. Forward of it is where the grub screw to hold the bottle adapter fits, it’s not pressurized. I threaded it, drilled a hole in the adapter for a pressure source and use a Teflon washer.

I also made my bv externally adjustable.

I also added a cf tank.

This is a really fun gun to shoot and mod.

Dave 

[MJP]

Nice looking stuff David!
I dont want to use any conventional valves anymore.
Some auxiliary force helping the valve open is a must.
Light cocking is pleasant to use and gives nice trigger pull too.

Marko

[sb327]

I agree, the human interface with the machine should be minimal. Cocking or trigger pull. I also like the idea of keeping the mechanical interface as nice as possible. A small, fast hammer strike seems less disruptive to a heavy hammer strike.

I hope my pilot valve works out as planned, I’ll be switching this over to it.

Dave

[customcutter]

Have you installed the new parts yet?  If so, did you notice any improvements in accuracy, shot count?  Lower hammer spring pressure should be a great mod in itself.

[sb327]

The balance valve definitely helped in the accuracy department due to the lighter hammer strike needed.

Shot count I’m not sure about. I didn’t really collect data for a before/after comparison.

I’ve not incorporated my pilot valve into this yet because I’m developing it on a dedicated build. (Leshiy2 inspired build)

Dave

[customcutter]

Thanks, I'm thinking of getting one of the AEA HP semi-auto carbines for pesting.  Looks like they have corrected a lot of earlier problems, but I'm still seeing a few videos with other issues like pellets, and chips being found in the shroud. 

Did you add the CF tank for weight reduction or extra shot capacity?  I asked a dealer and he said there was just a few ounces difference in the CF and Al tanks? 

[sb327]

Yeah, just a weight thing. But I’m constantly swapping things around just cuz. It may end up with the al back on it.

I’ve actually have a .257 barrel on it that I set up for it to see how slugs would do. Just a time thing now.

Dave

[Spacebus]

I wonder if there is enough market to produce these valves for customers? I can say that I would be interested in one for my small bores, but I don't have the expertise. Perhaps this is cost too prohibitive to bring to market and I'll just have to dream!

[sb327]

Somebody may want to but I’d imagine the sales would be small. Due to the fact that it’s not really a big deal for the semi owners as they really only cock the gun once per mag. And you don’t here much talk about the varmint/bolt action HP’s.

Dave

[Spacebus]

Somebody may want to but I’d imagine the sales would be small. Due to the fact that it’s not really a big deal for the semi owners as they really only cock the gun once per mag. And you don’t here much talk about the varmint/bolt action HP’s.

Dave

I meant for non-AEA guns. My SPA/Diana Chinese made bolt action small bore has broken two bolt handles, and bent another, with the heavy spring. A balance valve would make that pretty much non-existent, but then a hammer spring has to be figured out.

[sb327]

I’m not familiar with those valves, I’m sure they are close to a typical knock open. Maybe there is a pic floating around the net of one, what’s the model?

Dave

[Spacebus]

I’m not familiar with those valves, I’m sure they are close to a typical knock open. Maybe there is a pic floating around the net of one, what’s the model?

Dave

https://spares.bagnallandkirkwood.co.uk/wp-content/uploads/2019/08/PP800-Diana-Bandit.pdf

That's a link to a PDF showing the valve. The bottom locating screws on a Stormrider are reversed and the cap is taller.

[sb327]

Sure looks tight in there. When I see tapered poppets (in conventional knock open), I think it’s a manufacturing design that insures sealing at the expense of cocking force. I understand why and don’t argue the point but it also leaves a lot of room for improvement. The general populous just wants a gun with zero leaks.

I think the better approach to this valve would be a smaller stem and a flat face poppet from peek.

Dave

[Mr.P]

I know this is an old thread but I wish I had seen this when I first got my AEA guns so I am going to reply especially since it was referenced in another thread recently. That is amazing work on the varmint and I’ve been wondering if anyone was really messing around with the internals on these air guns.   

[rualert]

     Dave, could you possibly get some pictures, and maybe give us less talented machinists some pointers on making one of those valves sir? I would very much like to do so fo my HP Max SS+ and also perform a 257 switch barrel conversion too. Then I can shoot 30 and 257 slugs.. 

Thanks in advance sir,
Casey

[sb327]

Keep in mind that the semi auto hp’s rely on the hammer spring as part of what resists the bolt from ‘blowing out’ from the chamber too soon. I have no idea what making the hammer spring lighter (the main reason for a balanced valve) will do with a semi.

That said, here are some detailed pictures of the valve I currently run. It is externally adjustable but can be made internally adjustable as well.

Dave

[sb327]

In those last two, you can see how much forward float the balance piston has. Notice the adjustment screw has not changed, the two pictures are just to show how the piston is free to move.

Dave

And one to show depth of balance chamber.

[Firewalker]

Great stuff! I just wish I understood it. 

Great timing for me as well as I am buying a Varmint in .25 and want to reduce the trigger pull and cocking effort but have no idea where to start.

Dave, is there a drawing available of the balanced valve?

[sb327]

I’ll try to draw something up that is close to scale. It won’t be exact but it’ll give a good idea. I’m heading to work shortly and it’ll be a couple weeks before I can do any more measurements and such.

Dave