.22-250 Resizing Die Expander

[gitano]

Sometimes its better to be lucky than good. 

You may recall the hassle I had with getting the .22-250 resizing die set up. Part of the hassle that I didn't mention was that the expander ball was not original to the die. As such, during the various machinations of getting the die right, that expander ball got broken. (Since the original was gone, I assume it too was broken. Those .22 caliber expander balls are quite delicate.) No matter. "I'll just make another", he says casually.  Four hours later, I have a new, excellent, expander ball for the die.

While I knew it wouldn't be trivial, it was more time consuming than I thought. And before someone tries to defend manufacture's pricing with the above comment, on a CNC lathe it would have been complete in 5 minutes. That's not an exaggeration. But, neither do I have a CNC lathe, nor am I a manufacturing machine shop. 

Lemme 'splain the process. (I was too busy 'paying attention to what I was doing' to take pictures of the process. Sorry.)

There are several critical details. The most obvious is probably the outside diameter. After all, this specification defines the ultimate performance of the thing. However, trust me when I say that's not the most important spec, and it is the easiest one to achieve. There is the hole in the distal end of the expander through which the decapping pin extends. Again, at first blush, no big deal. Just measure the pin OD and drill the proper hole. (1/16th of an inch.) Yeahbut... There are other holes that that hole has to coincide with.

The first one is the diameter of the split, unthreaded, TIP end of the decapping rod. That's the part of the rod that holds the decapping pin. 1/8th of an inch.

Then, there's the threaded part of the expander ball. First a hole of proper diameter for cutting threads needs to be drilled, (#29 or 0.136"), then that hole needs to be threaded with a pitch of 32 threads per inch - #8 diameter.

"Piece o' cake" you say? Well sorta. Until you realize that each one of those holes has to be the 'perfect' length/depth.

The 1/16" hole is "easy", because being the smallest, it's the first. However, I broke two 1/16" inch drill bits drilling that 'first' hole, and I was being very careful, advancing no more than 1/16" before retracting the bit and clearing chips.

That second hole, 1/8" in diameter, had to be 1) exact depth and, 2) have a 'point' on the end of it to act as 'wedge' to close up (tighten) the split end of the decapping rod around the decapping pin. I had to use a drill sharpening device to 'point' the 1/8" bit. It couldn't be too deep or it would punch through the 'wall' at the distal end of the expander, and it couldn't be too shallow or there wouldn't be enough threads for the decapping rod to screw in as far as required to get hold of the expander.

Finally, the hole for the threads that screw onto the decapping rod. It needed to be deep enough for enough threads to grab onto the decapping rod, (remember, there will be great deal of 'pushing and pulling' on the expander), but not too deep to interfere with 'holding on to' the decapping pin.

Here's the perfect place to illustrate how a 'pro shop' would render all of the above into one simple step: A custom 'bit' that is shaped exactly for performing all three drilling operations at once. A 1/16" drill 'point', behind which was a 1/8" drill for the tip of the decapping rod, followed by a 0.1360" drill to make the hole for the threads. It's possible, that drilling all three of those holes with that bit, might take only 30 seconds. Followed, immediately by threading the 'outer' hole.

I had a 'bottoming' 8-32 tap, so threading was pretty straight forward for me once the other holes were drilled.

The only operation left was profiling the outside of the expander.

Which brings me to 'lucky' instead of 'good'. I knew that this OD had to be 'just right'. Too big, and the case neck wouldn't hold the bullet. Too small and the grip would either be too tight, or wouldn't even allow a bullet to be seated without crumpling the neck.

I measured the OD of other .22 caliber expanders I had; several times. I had the dimension I wanted down to a precision 0.0001". 

Remember, I've got hours invested in this thing by now. This was the last operation. Too big, doesn't work but I can probably fix. Too small, throw in trash. Recall too, how small this whole thing is: 0.2245" OD, and only 7/16ths long. 

Anyway, I parted it off and polished it up, threaded it in the decapping rod, and ran a case through the die. I then took a boat-tail bullet and, using my fingers, tried to push it in the case mouth. "No go." Good. Press harder. Hmm... Goes in. Maybe not so good. Pull the bullet out. Ain't happenin'. Good. In the end, it turns out that, at least for now, I'd call this neck tension almost 'perfect'. (Lucky). Tight enough to hold the bullet in, (little recoil in . 22-250), but not 'too' tight. We'll see how it works in the rifle. If it's too loose, I may be able to snug it up a bit, but I don't think it will be.

Paul

[Jamie.270]

So, are you going to harden/temper it?
Or order a replacement to have on hand in the event of an unfortunate occurrence befalling this small masterwork?

Inquiring minds,...

[gitano]

I thought about hardening it, but I recently bought a pair of scope rings, (for the Sauer 90 .270), and to my surprise, they mentioned the steel they used to make it: 12L14. That surprised me for two reasons: 1) 12L14 is 'free machining' steel, meaning that it has lead in it to facilitate machining, and 2) since I have some 12L14, I know from personal experience how 'soft' it is. (It does machine very nicely.) Of course a pair of scope rings should never see the use a reloading die expander ball will see, but... as I have said many times, I'm not a production shop, and my dies don't see in my lifetime, the use 'commercial' dies see in a week. So, the short answer is "no", to both hardening and buying a 'factory' backup. If I break this one I'll just talk like a sailor for a minite and make another one.

I have considered making a custom, two-stage 'reamer' to facilitate fabricating these things. (I'd still drill the initial 1/16" hole with a separate bit.) That might be fun if I do it before I need it.

Paul

PS - This expander is made of cold rolled 1018, which is harder than 12L14. Also, I forgot to mention that hardening, especially in a threaded piece as small as this, can result in the threads being sufficiently distorted that they wont work. Machine shops have means at their disposal that prevent that distortion, that I don't.

Paul