I'm finding it very un-ergonomic to lock the action open on my A3M1.
I'm constantly folding the handle up partially which doesn't engage the slot in the receiver.  The fine motor skill needed is frustrating (for me) under ideal conditions.
My understanding is the A1 handle is rigidly attached to the cocking piece (doesn't fold).
If that's the case, can I install the A1 handle and cocking piece in an A3M1?
Would that configuration have forward assist via the button on the CH?
Just wanted to check before I throw money at this.  I'd like to make this work like an HK-series subgun; tug back and flip handle up to lock.  Doable?
Thanks!

That's correct that it doesn't fold, and that the button enables forward assist on your existing action rod.
I have not personally installed one, but they should interchange. 


It should already work that way with your A3 handle. You just have to make sure you push it near the joint (bottom), so the cocking piece rotates inboard with the handle body. That inboard rotation should be a little easier with the older fixed handle.

Will the A1 type gouge the receiver on an A3 in the same way they tended to remove finish on the A1?

My understanding is the A1 handle is rigidly attached to the cocking piece (doesn't fold).

Correct.

If that's the case, can I install the A1 handle and cocking piece in an A3M1?

Pretty sure you can, but I've never tried. This is also how the new StG77 will be. I think the reverse (A2 CH on A1 receiver) will not work because the slot is different width.

Would that configuration have forward assist via the button on the CH?

Already answered, but yes.

Doable?

Yes. I actually highly prefer the A1 CH to the current A2 CH.

The A1 CH didn't "gouge" the receiver, but the plastic handle did scrape off the paint that the old receivers were coated with. Using a plastic A1 CH on a new A3 M1 receiver that's anodized won't hurt anything.

It does, but even when I'm consciously paying attention to it, sometimes the action slams closed because I bent the handle up just so slightly instead of fully rotating.  I find it a bit like that childhood game of trying to "pat your head while rubbing your stomach."  Looking for a more idiot-proof option, and it sounds like the A1 CH may be just the ticket.  Thanks to all who responded.

Let us know how it works out if you end up swapping it out for A1 handle. Im not a big fan of the A3 charging handle either for the same reasons you listed, it is a stupid design IMO. The trick is to keep pressure on the absolutely lowest point of the handle while pushing up, your hand should not come off the reciever when rotating the charging handle up into the locked position. My one AUG is noticeably easier to lock back than the other for some reason also.

Just pick one of the great aftermarket choices. I prefer the Manticore folder.

I briefly talked to Pete about it yesterday, and he said A1 CH should work in an A3.  If he has the parts in stock (he was away from the shop and wasn't sure), I'm going to try this out and report back.  Emailed him CC info and shipping address; fingers crossed.

A box of A1 CH parts from Pete arrived this week, so I took a shot at installing this afternoon.
Getting the A3 handle and charging assembly out went smoothly with the help of YouTube.
The new A1 charging assembly dropped in fine with no issues.
It's a little narrower than the A3, so there's a bit more "play" in the receiver slot:


The charging handle took some fitting; it's ~1/16" (approx.) longer front-to-rear than the A3.
This dimensional difference prevented rotating the handle up to lock open.
Here's where the interference occurs:


So I shaved the plastic handle down slightly in the front and re-profiled to fit:


Another minor fitment issue cropped up; there's a small "hump" along the charging slot here:


The handle hits this and hangs up, making it difficult to work the action.
This cleared up by racking the handle forward and back a few times to wear it in:


Now it works exactly the way I want; there's no finesse required.
Plus it retains the forward assist function absent on some aftermarket options.
If you can work an HK charging handle, you can charge an AUG A1.
No more "surprise, SLAM!!" embarrassing attempts to lock it back.
Here's everything after installation:


Big thanks to Pete Athens for a fast turnaround on the parts order!

Nice work, glad to hear it worked out. I will be doing this to one of my AUGs soon.

Great follow up post deltaheavy. I've always preferred the A1 CH because it locks back easier. Might have to do this to an M1 I have in mind.