Before I started reloading, I bought several boxes of 7.62x25 new, commercial ammo. It turned out that a few out of each box had the bullet seated just crooked enough to cause it to jamb the side of the chamber or lands when chambered, and occasionally blow the primers.
So I decided to get a Lee hand press and a set of lee dies for 7.62x25 to try to straighten the crooked rounds out a little. The Lee dies did not usually help at all. I looked at the seating die, and found that the seating plug fit the nose pretty well, but there was so much lateral play in the seater plug inside the die, that it would just follow the crooked bullet. Then I tried some rcbs 30 mauser dies, and they helped a little more, but still not consistently. They were a little tighter in the die, but still not what I considered a precision fit between the case, the die, and the seater plug.
After I actually started reloading (45 colt) I liked the Hornady seating dies. But they don't make a 7.62x25 or a 30 mauser die set. They do, however make a 30 luger die, which has almost identical upper dimensions. So I emailed them and asked if it would work for 7.62x25, and they replied in the affirmative. So I bought one of those, and it does the job everytime.
To make a long story short, I think it is a combination of how the plug fits the bullet, how the plug fits the die, and how the die fits the neck of the cartridge that determines how well the seating die aligns the bullet. Dies like Redding competition and Forster bench rest, or all Hornady dies, have the sliding sleeves that align the bullet with the case before inserting the bullet into the neck. Redding or Forster may be better dies (they cost more), but they are not available in all calibers, especially handgun. Every seating die Hornady makes has that feature, plus they all accept an optional micrometer screw, and disassemble for cleaning without affecting the settings. And they can crimp too, if so desired.
Andy
