Adjustment: old RCBS 38/357 Taper Crimp Die

Haven't done any reloading in about 20 years and trying to develop a 38 spl HBWC round.  Found my old RCBS 38/357 (81) Taper Crimp Die. I do recall that when I used it long ago the groups really tightened up.  Problem is I don't have the instructions and can't remember how to adjust the die.

Wrote to RCBS but haven't heard back.  Searching online can only locate instructions for the taper crimp die "with bullet seater".  This die is hollow.

Any ideas?

You probably just screw it down until you get the crimp you want. That's the way most work.

If you have a round with the crimp you want, just use it as a guide and screw in by hand until you feel some resistance. Then tweek a little more when you start loading your rounds.

CR

May sound crazy but the other day I was sure that I used to seat the die flush. So I loaded a few rounds with 3.5 grains of W231 behind the swaged .358 HBWC and got a group under 2" at 50 yards. S&W Model 64 with Clark stainless barrel (probably 1/14).

Some effort to full length size them, but the cases look fine, no bulging etc. Then I started thinking about flushing it with a longer 357 case??? Maybe the die is a flush mount and opens up as the case gets longer?

Attached a picture of a sized case inserted in the die, it only has a short distance to fully seat.

Don't know what you mean by flush mount?  There's always has to be room for the shell holder / shell plate.  And most taper crimp dies don't have to go anywhere near to touching the shell holder / shell plate.  Simply measure the crimp on a factory and use that as your guide. You can crimp (even taper) too much. You do have calipers?

CR

I own one from the 80s. Same as any taper crimp screw it down until you get the taper you want. Great dies

Thanks folks...I'll make up a batch with various crimps...but do remember that this die tightened up the groups significantly with the HBWC.

Just reread what you posted. Maybe it looks like that because you haven't expanded the case to seat a bullet yet?

A lot of sizing dies are just slightly under or at nominal. Case is expanded for seating and then sized back to your desired crimp.

CR10X wrote:Just reread what you posted.  Maybe it looks like that because you haven't expanded the case to seat a bullet yet?

A lot of sizing dies are just slightly under or at nominal. Case is expanded for seating and then sized back to your desired crimp.

Using this die as the last in the series, the one before seats the bullet and sizes the case only enough to reduce the flare (no crimp) so the round will enter the taper crimp die.

Usually the seater die should be set to only seat, no crimp at all. This reduces the possibility of having the bullet still seating as any form of crimp is applied. For roll crimps, I'll even use 2 dies, one seat and final roll crimp separately. Keeps from getting that little bulge right under the crimp. Using any crimp before the taper crimp might turn the top of the brass in just a little, resulting in some scraping or varying tension.

CR

CR10X wrote:Usually the seater die should be set to only seat, no crimp at all.  This reduces the possibility of having the bullet still seating as any form of crimp is applied.  For roll crimps, I'll even use 2 dies, one seat and final roll crimp separately. Keeps from getting that little bulge right under the crimp.  Using any crimp before the taper crimp might turn the top of the brass in just a little, resulting in some scraping or varying tension.

CR

10-4  on that...but have to reduce the bell just enough so the brass mouth can enter the taper crimp die. Essentially the seater die is only seating the bullet OAL.  I have had better luck not using the roll crimp at all and going right to the taper crimp with these 148 non grooved wad cutters.

Found an article online here is what they said about taper crimps:

For taper crimp, practical shooting reloaders have been doing it long enough to have hard measurements. Take the bullet diameter, plus twice the case wall thickness and then subtract .004 inch. As a general rule, and rough estimate, you can count on a handgun case wall being right around .0001-inch thick. So for the .45 ACP, take a bullet of .452 inch, add .010 inch twice for a total of .472 inch. Then subtract .004 from that .472 and you get a goal crimp of .468 inch. Apply the same arithmetic for other calibers. A .40 or 10mm would be .400 plus .020 minus .004, which leaves us at .416.


Link:  https://www.handgunsmag.com/editorial/squeeze-play-how-to-properly-crimp-ammunition/138116

Late to the party but here’s a video that may be helpful.

https://youtu.be/IUXpQ3ChWRk

Don't want to beat a dead horse ..but I have tried numerous combination crimps with this 148 HBWC and W231 (3.5) load.  With the various roll crimps and numerous partial taper crimp loads..I run about 4" at 50 yards.  Then I run the same non crimped loads the "full length" (bottomed out) with this RCBS taper crimp die and the groups are easily under 2" at 50 yards?  Actually in the 1.5" range. (and the Federal cases look fine). FYI only.

FYI Only.....was digging through some old reloading boxes and found this old print out from Gil Hebard explaining how to adjust the TC (taper crimp) die.  Must have been included when I bought the RCBS die years ago.


OK tried to attach it as a pdf...not allowed...tried as a bmp....too large...when I reduce it further...can't be read.  If anyone wants a copy send me a PM with your email address.