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Old February 12, 2013, 11:44 AM   #14
Join Date: March 4, 2005
Location: Ohio
Posts: 12,357
Originally Posted by JD
I was also under the impression that you could prep your cases (sized, trimmed and deburred inside and out) before you put the shells on a progressive press. Is this an incorrect assumption? If so, why? This alone may push me towards that single stage press.
This depends on how you load. The problem is that case growth occurs mainly during resizing, so trimming before resizing won't get the case down to final size. In the gun the case expands to fill the chamber. When you insert it into a sizing die, the die narrows the brass, lengthening it, then pushes the shoulder back, leaving the excess brass looking for someplace to go, so it goes into the neck. Below is an exaggerated illustration I made:

As a result of the above, if you trim before you size, you have to trim extra. Unfortunately each case has some variations in brass thickness and work hardening, etcetera, so they don't all grow the exact same amount. In. .308 I've see, from the same lot of cases I loaded identically, one case grows none, another grows 0.005" (an average result with my loads) and another grows 0.010". So if you trim fired cases before sizing, even if you trim them enough so the longest case is not longer than the SAAMI case maximum, you will have length variation afterward. That isn't going to matter as long as you don't crimp or only crimp with a Lee Factory Crimp die. But it you try to crimp into a bullet cannelure with the crimp shoulder in a seating die, you will find your crimps are uneven.

Another approach to solve that problem is to use the RCBS X-die, for which you trim the cases to minimum just once, then the die design prevents growth back to beyond typical trim length.

The other factor in when you size is whether or not you clean the primer pockets when you clean the cases. For handgun accuracy this is not required. At rifle precision levels it doesn't matter much to accuracy until you are at a maximum precision level. If it builds enough it can affect primer ignition force some by cushioning the primer anvil feet a little. There is also an interesting argument by a former Aberdeen Proving Ground Test Director that the hardened carbon in fired cases and primer pockets contributes to a significant degree to barrel throat erosion. One of the advantages to depriming before cleaning and running through the press is that all the primer dust stays out of the rotating shell holder mechanism of the progressive presses.

So I think it's worth getting at least the bulk of primer residue out when cleaning. That means depriming the case before cleaning. You want to clean before sizing to remove dirt and grit that could scratch your sizing die, so if you allow the sizing die to deprime the case, you will miss cleaning the primer pocket in a progressive loading sequence. What I use is a Lee Universal De-priming Die on a separate small aluminum single stage press to remove primers before initial cleaning. After resizing I trim and clean case lube off before continuing, but you can clean loaded rounds if you are not interrupting the loading flow.

Originally Posted by JD
The benefit from going to a RCBS dye to the redding precision set was simply for a more precise setting (this is based only on the youtube video). I’m hearing from your response that while it may get the depth right, it may not get seated correctly.
Since you didn't put a link to the video in, I didn't realize that you were not talking about using a conventional RCBS seating die, but rather that you were talking about the one that is part of their automatic bullet feeder. That's a bit different. My concern was that if you were to seat the bullet most of the way with a conventional seating die and it did not start the bullet in concentrically enough, you would have added runout even with the Redding die. However, now that I found the Brownells video (I assume this is the one you watched), I think that if you set the bullet feeder's seating die up so the bullet only goes in far enough not to fall out on its way to the Redding die, you will be fine with that setup.

If you don't use the bullet feeder, though, the Redding die will be all you need and you will just feed bullets to it with your fingers as the case comes to that station on the press. I would not use one of the open window RCBS competition seaters as it will not give you concentricity equal to what the Redding die produces. You can see a review of that here, wherein the Vickerman die shown is the open window type. The RCBS one, specifically, was actually outperformed by a standard RCBS seating die when compared by John Feamster (Precision Shooting Reloading Guide, Precision Shooting Pub., 1995, p. 140).

Originally Posted by JD
how do you recommend changing dyes for each caliber without having to redial everything?
Did you note how the part of the press that holds everything except the priming and powder dispensing station is a white metal and not green? That's because it's a removable aluminum casting called the die plate. You can buy a separate die plate for each caliber you use and leave all the dies set up on it. The powder measure is used for them all, so it stays put. You can see the pins that locate die plate being inserted in illustration 10 on page 5 of the press instructions. Changing primer size and powder measure actuator tube done there. I recommend you read that whole manual to see what changing calibers involves.

By the way, that video left station 2 of the press unused. RCBS makes a lube applicator die that you can put in where the sizing die is in the video, and then the sizing die is put in station 2.
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