7x57, bullet seating??

andy12390

my uncle has just taught me a couple things about bullet seating and how you can seat the bullet a little ways into the cartridge and then chamber it (without powder or a primer) and the gun will seat the bullet in the rest of the way. i tried this when i got home and i did it, and my bullet got seated to 3.243 in. now, when i do this, theres marks on the bullet where the bullet has met the rifling. i have a factory load right here and its 2.956. also the crimp on the bullet sticks about .244 out of the end of the brass. is my reload sticking out too far?

mrbruce

Each barrel is going to be different as far as OAL is concerned.
Even bullets are going to be different out of the same box.
If your leaving marks on the bullet from the rifling when you push them into the case, you are defiately into the lands, and that will sometimes lead to high pressures.
Also unless the case you used to push the bullet into the case with has been reamed enough to allow the bullet to just barely slide into the case, you are not even close to a proper fit.

sandwarrior

andy12390,

I would take and measure the marks on the bullet with a dial caliper, and turn your seating die in that far plus .010. Your bullet should then be .010 off the lands. In the case of Berger Bullets you should put them right to the lands.

If you don't know exactly how far to turn your bullet seater in find a tap&die set(you will need one eventually) with a thread gauge. measure the threads. depending on the die set you might have anywhere from a 24NC to a 40NF. That is threads per inch. Take that number and divide the number one by it and take it to three decimal places.
An example would be if you had a 32 tpi seating stem. Each complete turn of the stem moves the seat up or down about 1/32 of and inch or .0315. -good luck.

Edit: sorry I had my formula backwards, do it the way I show posted now.

JustC

you have done what we call "jamm seating" using the rifling to seat the bullet. The problem with this method is that you probably still have a good .020"-.050" of bullet jammed into the rifling. be careful using this method as it can and will run pressures up very quickly once you hit a certain point.

try shortening the load until the scars go away, and set the die there.

PA Shootist

Another problem besides the possibility of high pressures: if you decide to extract the case unfired, the bulet might remain wedged into the rifling, and pulls out of the case, spilling powder and nearly disabling your rifle (if you're not equipped with a cleaning rod if this happens).