Yes, it sure looks secure. Whether the Forster reamer shanks fit it or not, I can not say though. Thank goodness you only have to do them once cause it looks like an entire evening job as you mount, ream and unmount each case. My intention was to have Forster make me a custom reamer, to use on newly cut-down, unsized brass. They cost a little more than an off the shelf standard size, but should last a long time. I believe Siringo may have some insight if he reads this, as he had one made. IIRC, it was .445 or .446 inches. There's actually a post on it somewhere. Perhaps my concern for controllability is unfounded and the reamer will track straight as long as you don't try to go too fast. I have no experience reaming or turning necks to fall back on, so it is uncharted territory for me. Now if you could accurately measure the ID of new brass, given that it's parallel at least when it's new, you could have Forster turn the first 1/8 inch of the reamer down to that diameter and then it would center itself ahead of the cut on the interior wall. I've heard that Forster is very flexible in making a custom reamer and possibly would do that for you. If I'm not busy tomorrow at work, I'll give them a call and ask. That would definitely make me find my wallet as I could use my Trim Pro then.
My problem is that long after some of my postings regarding case internal dimensions, I discovered my caliper internal jaws did not read the same as the external jaws. You'd really want to get that ID measured accurately before you pay Forster to make your reamer with a piloting tip. Unfortunately, I seem to recall that I already resized my new brass, so the internal walls will not be the same ID all the way down. I'd have to get some more new brass, cut one down, debur the mouth and remeasure the ID with the caliper, then check the caliper with my precision micrometer to feel good about the dimension. The local reloading shop sells loose .284 brass. Perhaps I will stop by after work and pick up a piece or two.
Lastly, but not least. This is all a lot of fussing to manufacture an alternative to just buying the Hornady brass. Don't forget the tedious process of narrowing the rims and extraction grooves. You don't want to brake your extractor claw. That took as long if not longer than chucking each case in a lock stud, spinning each of them them slowly in my drill press while I cut the .284 cases off to produce the 1.75 raw cases with a dremel and cut off disks. That was an evening job right there alone, but it produced the cleanest and consistent lot of brass. I then turned each one around, chucked it again in the press and while they spun slowly, I laid a file to the rims to take them down to .468 from .473. Then repeated the process, only using a fine oval needle file to do the extraction grooves.If Hornady made their brass to a little tighter standard, like all of them actually being 1.70 from the factory, we would not be having this discussion. The last box of 50 I bought varied from 1.692 to 1.70 and as we all know, they shrink with each shooting and resizing down to a point. While I'm wishing, why not wish big and wish I could get a box with all of them 1.75.Then measure the inside of my chamber precisely and trim them to that length minus .001. Then after a shrink or two, they would be at 1.70. I did once seat a .284 case, sized and trimmed to 1.703 and it still did not bottom out on the chamber lip, so I know Bushmaster cut mine longer than 1.70.
Believe me, if you have time to kill and want to peruse the archived calguns posts as well as the ones here, you will find a lot of discussion about using .284 brass. Like Tim once suggested, if the chamber was not chromed, I'd just have it opened up to use unmodded, cut back .284 brass, but then I'd have a unique gun and would probably have to have the barrel stamped so that if someone came into possession of it after I pass away, they did not try to use factory ammo in it.
I may have found a way around the goofy search filter suppressing common or short terms. At the end of the word, add an asterisk. IE instead of .284, try .284*. It seems to slip through then.
Hoot