Turning .284 brass into 450 brass?

[BD1]

Here's the rest. the last time I made brass in 2009, I had a good triple chip blade in the saw at work. This time I had a somewhat used 80 tooth trim blade in the saw at home and the cuts were rougher and burred. I'd recommend a better blade. I just didn't have an excuse to expense an $80 triple chip right now. This meant I had to chamfer the inside of the cut case mouth before trimming it, and then again after.
BD

[wildcatter]

Does that BD do good work or What??..

..t

[Hoot]

I'm not a conspiracy theorist. I chide folks I work with who are.

We all know that manufacturing tolerances vary from one unit to the next. Reamers wear. Custom parts suppliers can't always keep up. Close, but not exact substitutes get used. When your phone is ringing off the hook from hungry distributors and you can't get enough custom bolts or custom extractor hooks to even come close to ratcheting up supply, maybe you settle for ones that are looser toleranced, or ones for a 7.62x39 instead. Maybe you produced higher quality assemblies early on to develop a demand base, only to discover that the demand snowballed until you can't keep up, based on the quality standards of the early units. Maybe maybe maybe.

For the few folks who have tried .284 brass, I suspect if polled, they would report surprisingly different results. Not because they got up on the right or wrong side of the bed. Not because they used the wrong techniques. Not because they started with out of tolerance brass, but because not all units were created precisely the same, especially once the sales department was screaming on the phone to the manufacturing department. I sincerely believe these different results speak volumes. Bushmaster is not designing the 450b to work with .284 brass and Hornady is not producing brass with the same rim, extraction groove and wall profile as the .284. Getting the two twains to meet is as much luck and art as it is precise workmanship and raw materials that are to spec. If you take a new Hornady 450b brass and it fits in the chamber fine. Then you seat a bullet and it fits into the chamber fine. Then you take a piece of cut down .284 brass and it fits fine. Then you seat a .452 bullet and it doesn't even come close to fitting in the chamber. Then you squash the bullet by squashing the brass to make them fit. Then you are bandaiding the problem, not solving it.

I referenced this image a few posts back. Look at the bulge. That's not just bad luck.



After sizing the outside of the cases down to where they would thunk, the pulled bullets from those cases measured .444-.446 OD. That is not my idea of a recipe for accuracy or repeatable results, even with the small amount of obturation from a copper jacketed bullet, when going down a .452 grooved bore. That's approaching a musket.



Hoot

[wildcatter]

John,

I guess the conspirators are on your case and that lot of brass might have to be inside reamed. I personally have not had your prblem, but maybe that's been just the luck-of-the-draw for me. You're right, the .444-.446 OD is unacceptable. I know you've said, but what is the case thickness, jsut after cutting to length, at the case mouth? At this point, the only thing I can come up with, at this moment, is to ream..

..t

Ps..I know you've done this, but just as an after thought, are we sure the bullet dia is at least .450"? ..t

[BD1]

Hoot,
Methinks you do have a chamber on the small side. And, I may one on the loose side as my rifle will chamber cases measuring .480 at the case mouth all day long, clean or dirty. From your photos it looks like you're seating a little deeper than I do as well. I seat all the Hornady bullets out to 2.250, even the 225's.

On the plus side a tight chamber should give you better accuracy with the Hornady brass.

What's the case wall thickness of your .284 brass? I have a variety and I'll try to measure them this evening. I'm sure hoping that my new batch isn't too thick to use now that I have 300 of them. I sure never get the heel bulge that your photos show.

Maybe we need a broader sample? I'll donate 20 cut down .284 cases, one each to any 20 guys willing to seat a bullet and try the thunk test in thier rifle. PM me your mailing address and I'll send you a case.

BD

[Hoot]

Hoot,
Methinks you do have a chamber on the small side. And, I may one on the loose side as my rifle will chamber cases measuring .480 at the case mouth all day long, clean or dirty. From your photos it looks like you're seating a little deeper than I do as well. I seat all the Hornady bullets out to 2.250, even the 225's...snip
BD

Hold the mail Ed. I'm at work, but your mention of COL just caused an important revelation to peek around the corner at me. I can't resolve it until I get home. In 2 weeks, it will have been a year since I walked away from the .284 project, putting it on hold and it may well be a year lost in vain.

Clue: The bullets were seated to catch the front cannelure with the taper crimp. Look at the far right cartridge in that thunk picture. The shiny spots are where the sizing die caught the high points. It's a 200gr FTX, not a 250 (hint smooth sided bullet).

This image is from my stickied FTX Bullet Comparison thread. Do you know how they press cannelures into a bullet? What do you think happens to the displaced copper jacket?



I'll elaborate once I can run it to ground with a .284 case and 250 FTX (non-cannelured) bullet after supper.

Hoot

[Stealthshooter]

BD1 is the man I will say that much!! He is helping me out like you wouldn't believe!! Hoot I can see how the cannelure may cause a problem. When they put the cannelure in that copper flows out of the way I'm sure so it very well could make inconsistencies in the bullet.

[BD1]

I just spent some quality time with a tubing micrometer on a stand and Hornady, Remington and cut down .284 brass. I described the set up and typed the data in here only to have it vanish when I hit submit. Now I'm tired so I'm cutting to the chase: I indexed the brass so I was measuring the point at which the heel of the bullet contacts the case wall at the deepest point. Where Hoot's bulge occurs.

Hornady brass was .0145 at the thickest and .0137 at the thinest which yields a cartridge diameter of .4802 at this point with a 250 grain FTX.

Remington brass was .0142 on the thick side and .0131 on the thin side so the critical dimension would be .4793

Cut down .284 brass measured .0167 on the thick side and .0162 on the thin side yielding .4849 at the critical point.

So the cut down .284 brass yields a cartridge that is almost five thousanths fatter at the base of the bullet than the factory Hornady brass. If you have a tight chamber this could indeed cause an issue.
BD

[wildcatter]

BD1 is the man I will say that much!! He is helping me out like you wouldn't believe!! Hoot I can see how the cannelure may cause a problem. When they put the cannelure in that copper flows out of the way I'm sure so it very well could make inconsistencies in the bullet.

Yuppers, when you have two Heavy-Weights, like these two here, solving problems, yacking back and fourth, well,the Sparks are just bound to Fly, and the rest of us learn all the while.

Go Get'em Guys!!..

..t

[Siringo]

If you shoot .452" bullets, not .450, .451 or lead that can be squished down, the inside of the cut down brass has to be reamed . It is easy to do with a Forester Case Trimmer. When I cut the brass down,trimmed, ect, I sized it in the Hornady die. After that, I reamer the inside to a internal diameter of .446 inches. I had Forester make me a reamer to the size that I wanted. In doing so, the inside case wall thickness is now the same as the Hornady brass (after sizing, but before expanding) -- for at least a 1/2 inch.

The other way to do this is to use undersized bullets, fire the brass, then ream the inside neck to .452 inches or .453 inches. Either way gets you to the same point. It is just easier to do it during the initial preparation.

The whole idea -- IMHO -- it to make a case that duplicates factory, to minimize hassles in reliability with the reloads.

Also note that powder charges need to be reduced because of the small internal volume of the 284 case and the overall case may not seal well in the chamber.

I came to the conclusion that if all went to hell and I could not find Hornady loaded ammo or brass -- my fall back would be using 284 cases. But as a general rule -- to me it is not worth the hassle.