AEA HP SS Max 357 Project

[caliusoptimus]

More mods to this bad boy.

I slapped a 36" TJ barrel on there. Why? Why not! 290fpe with 132gr at 250bar. Curious to see what it will do with 200gr and 300bar! Velocity is pretty consistent with the HS in the right spot... ES around 10fps and SD around 3 for 10 shots. Externally regulated.

Also cut a chunk out of the breech area to make room for longer slugs. Longest I have is 21mm and they fit no problem now.

After a couple hours of shooting from a bench it was obvious it needed trigger work. I took a tad bit of material off the sear, but more importantly there were 2 springs that were way too strong. I took out the springs and swapped them for some springs out of a pen. Best I could do in a few minutes, works fine, trigger is still safe but very much lighter.


Still not done with this project. Need a fixed stock that has zero wobble, with an adjustable cheek piece and a bag rider. That's top priority... the original stock is terrible. Also need to do a picatinny rail instead of dovetail. And a scope level. An internal regulator (that doesn't suck) might be possible. Also maybe a 42" 1:20" barrel (most powerful 357 AEA ever?). A nicer bipod would be great too.

Edit: side note... even with 36" barrel this rifle really isn't awkward or heavy. I like it more than I thought I would.

 

[Ezana4CE]

@caliusoptimus I like this thread. I literally laughed when I read about swapping trigger springs out with those from a pen. Hey man if it works, but it just reads funny. Do you have any plans to replace the reservoir with a longer one like once from a Zeus or another AEA model with longer reservoirs? I’m not too familiar with their line up. When you get it dialed in let’s see some groups and chrony numbers with that TJ barrel. What’s the twist rate on that barrel? Which style slugs are you shooting?

 

[caliusoptimus]

@caliusoptimus I like this thread. I literally laughed when I read about swapping trigger springs out with those from a pen. Hey man if it works, but it just reads funny. Do you have any plans to replace the reservoir with a longer one like once from a Zeus or another AEA model with longer reservoirs? I’m not too familiar with their line up. When you get it dialed in let’s see some groups and chrony numbers with that TJ barrel. What’s the twist rate on that barrel? Which style slugs are you shooting?

That's the stock tank. It's pretty much perfect size. With an external reg it's twice what it needs to be. With the internal reg and plenum it's good for about 15 shots at 200bar.

Barrel is 1 in 26" twist. I put a few hundred of the slug below (lee mold, pure lead dropping at 132gr) through it to map out hammer spring, pressure and velocity. Never had good luck with that slug... but it deserved one more chance. Still not great. 10 shot groups, 1.25"ish 50yds, 1000fps.

 

[Ezana4CE]

@caliusoptimus I was asking about the reservoir because I think you can get away with a longer reservoir with that long barrel. I mean why not up the shot count of you only have to install a longer reservoir? Have you slugged the barrel and micced those slugs? How do they load into the breech? Loose? Tight? Just right? At 1000 fps they are gonna do some damage upon impact. Did they group better or worse around 850-900 fps?

 

[caliusoptimus]

@caliusoptimus I was asking about the reservoir because I think you can get away with a longer reservoir with that long barrel. I mean why not up the shot count of you only have to install a longer reservoir? Have you slugged the barrel and micced those slugs? How do they load into the breech? Loose? Tight? Just right? At 1000 fps they are gonna do some damage upon impact. Did they group better or worse around 850-900 fps?

All of the TJs I've had mic out to .358 or .3585 grooves. I cut the freebore on this one to .3595... which was an oopsie... was going for .3585... guess it is what it is. Forcing cone is 1deg. Shorter slugs have a jump to rifling, longer ones may or may not depending on the ogive. Longer slugs also may not stabilize with 26 twist. Haven't tested that yet.

Lowest I tried with these slugs in this barrel was 900. I've tried them on many other occasions at different speeds without noteworthy results.

 

[Cheplicki]

that is a sweet build !!!

 

[caliusoptimus]

Still working on this bad boy. I picked up a 42" 20 twist barrel and machined it to fit. Along with being longer the new barrel has some different chamber geometry specifically designed to match a range of custom slugs. See more on that topic here: https://www.airgunnation.com/threads/slugs-molds-designing-making-and-testing.1316347/page-3

I've noticed something when testing my tensioned TJ barrels on a few different rifles... and it gave me an idea. Up until now I've been tensioning the liner by threading a cap against the varbon fiber shroud. This works, but as you shoot the barrel cools and makes the fit tighter. I noticed this after putting tension on a cold barrel and checking it the next day. It was completely loose! This is with the 42" barrel... seems more significant the longer the barrel.

So... to keep this from happening... and hopefully providing more consistent tension vs temperature... I came up with a fix. The barrel is now tensioned against belleville washers (springs) that should take up the difference in length as temperature varies.

I'm guessing none of this is a new idea. Some manufacturer has probably tried it and either loved it or hated it... but I'm in a vacuum over here... only owning a few rifles I don't get to see what everyone else has done. Hopefully it has a positive effect.

 

[Jaxjax]

Second concern is the design of the chamber/leade/-that area before the rifling starts-. On the stock barrel and on the barrel I have currently, the slug seems to have a lot of wiggle room before it is fired. I don't know if this is contributing to poor accuracy but my gut says yes. I imagine the slug hitting the rifling at a slightly different angle every shot. In any case, if/when the TJ liner comes in I'm going to try something different.

One of the most important pieces to the puzzle is a straight and uniform throat that is concentric to the bore. The bullet must get started into the rifling straight. If it doesn’t; it will become somewhat deformed and will not be centered in the barrel. Upon exiting the muzzle it becomes free to rotate around its new center-of-gravity, departing from the centerline of the barrel. In effect it will make a corkscrew-type path around the barrel centerline.
C/P from Lilja website....