Good post.
I'm just getting into expanders which makes me curious about these combo die / mandrels, I had a look but its not clear to me how they work.
Does your MA die look like this? Looking closer it looks like the stem is the same size at each end and step down a little thinner in the middle?
View attachment 7649832
So how does it work? if the stem is the same size at each end I am most curious about how the dies sizes the neck (most dies undersize and then drag an expander ball back through to open it up to the correct size).
Does the mandrel sizing happen on the upstroke (when being dragged out of the neck like an expander ball) or on the downstroke (not sure how that would work with the need to typically undersize at this point to allow for brass thickness / spring back)?
Which leads to my next question - will it still work effectively if the necks get thinner? I am trying to decide between bushing and non bushing dies (each has pros and cons) and I'm going round and round in circles.
Sorry for the list of questions but I bought a MA decapping die recently and its a good product and they were great to deal with, if their reloading die fits the bill for what I want then I will be picking up one of them too.
So if you look real closely at the shaft you'll see there's a section of the shaft right past where the tip screws in that's fatter (shaped like a barrel):
That's the mandrel portion of the shaft. Mine measures .241", which is exactly what I have been using and what I want.
It looks a little wonky at first (at least it did to me), but in-practice it seems to do exactly what it's supposed to do. It looks like it acts like a normal mandrel on the way down/in to the case, and then also contacts the neck on the way up (sort of like a much "kinder, gentler" form of expansion than a traditional expander ball).
It seems to do the trick, and like I said earlier, I was skeptical, but the ammo I've been making with it is every bit as good or better than I made before using the separate specific dies and doing the processes separately. Those pics I posted earlier tell the tale, I don't know if I stepped on that case and drove it into the gravel or what, but it was fucked up, and the MA die fixed it up no problem.
As far as how it will do with thinner necks? IDK. Time will tell... the MA dies are indeed honed to a more "relaxed" neck size than a traditional FL die would be for sure, and don't work the necks as hard as an off-the-shelf FL die, so if one was using really thin stuff they could run into a problem I suppose...
For me with 6creed, I had used bushings at .269", .268", and .267", mostly settling on the .267" bushing for my stuff, and the MA dies seems to be set to that or something real close - most traditional FL dies are a little tighter at maybe .266-.265" so they'll size just about anything (overdoing it in the process and terrible for guys who don't anneal every firing).
FWIW the brass in the pics from earlier is blue-collar Hornady with ~8-9 firings on it, so it's certainly not Lapua-thick by any means, and things are working fine for me. I also have a mutt/mongrel set of 100 cases going that's "practice only" consisting of ugly cases from when I was first learning to reload for rifle and was an idiot, and repurposed 22-250 cases from PPU and Hornady mixed in, the Hornady ex-22-250 necks are super thin and they shot fine after a loading cycle with the MA die (they are just too thin to survive my usual standard setting on the AMP I found out hahahaha).
I do know that after talking to Wayne at MA, I'm not too worried about it. I had called to talk about the prospect of needing/wanting a different mandrel OD if I wasn't happy with the neck tension I ended up getting, and ended up talking to Wayne for a while... He's really into making a superior product than the bigger companies offer, so I doubt one would find themselves in a situation where Wayne would leave them out in the cold... I got the impression he'd custom hone a die and/or custom turn a mandrel shaft if that's what it took for his customers to to be happy and continue to consider MA the best.
One of the things I found enlightening was: Wayne seems pretty pumped about the types of metal he uses: he said multiple times that he takes pride in using hi-tech metals that start off in pure powder form so his stuff ends up perfect hardness and without voids... Personally, I think he's on to something. You can feel it when you use the dies, they're made out of nice tool steel like a good knife maker would use, not the usual cast stuff that traditional dies are made from.
Maybe just give MA/Wayne a call? He's a funny dude with a definite "cynical yankee" type of wit, I bet he'd be happy to answer any questions you have...
Hope this helps.