Fireforming

[jtoews80]

I hope this hasn't been discussed already.

Sorry to always be the one asking questions, but I need a little help fireforming. I bought a 257 wby and shipped my 7STW. Now I've got 50 new W-W 7mm rem mag cases, neck sized to 264 and then FL 257 wby. I used the redding sizing wax for the first time and am not sure why I didn't try it sooner, GREAT STUFF. Now these cases fit the new wby vanguard, but the bolt is a little tight. I am assuming this is because of the slight bulge at the shoulder due to the wby case having a bit less taper.

It isn't much of a bulge, but enough to see with the naked eye. Fireforming should remedy this I hope???

Also, heavy bullet and start charge??? or go heavy bullet and medium charge to really snap it into shape??

thanks for the help.

CC.

 

[kraky]

I don't have a cartridge chart in front of me but....if the 7mm "base to shoulder dimension" is longer than the 257 then you have to make sure the shoulder is pushed back far enough to match your chamber dimensions. I would screw in the sizing die a bit more and see if that takes care of the chambering.
Re fireforming....I'd take whatever you think would be your normal hunting load and try a few at the range. They could shoot just fine. Actually if you buy new belted mag brass in any caliber they are usually quite a bit more undersized than most chambers. What I'm trying to say is your "reformed" cartridge dimension may be as close to factory dimensions as new brass would be.

 

[onesonek]

I hope this hasn't been discussed already.

Sorry to always be the one asking questions, but I need a little help fireforming. I bought a 257 wby and shipped my 7STW. Now I've got 50 new W-W 7mm rem mag cases, neck sized to 264 and then FL 257 wby. I used the redding sizing wax for the first time and am not sure why I didn't try it sooner, GREAT STUFF. Now these cases fit the new wby vanguard, but the bolt is a little tight. I am assuming this is because of the slight bulge at the shoulder due to the wby case having a bit less taper.

It isn't much of a bulge, but enough to see with the naked eye. Fireforming should remedy this I hope???

Also, heavy bullet and start charge??? or go heavy bullet and medium charge to really snap it into shape??

thanks for the help.

CC.

The only time I use heavy long bullets during fireforming, is if I have to to get headspace off the lands.
One ? first however,,,,It seems in your necking down you are getting a compression fit,,,Is that with a bullet seated?
The tight fit is a good thing provided it isn't caused by a thick neck from necking down.
Otherwise, when I have a fit that you describe, I use cheaper light weight bullets, and the the faster powders listed in the manual at starting or one gr. over start. I feel these faster powders generate pressure quicker giving a better forming. Try a few, first and see how it goes, if not fully formed it's not real critical, but you can bump up the charge a 1/2 gr. or so. Don't quote me on this, but if I remember correctly, I recall it takes about 36-39000 cup to fully form brass, but that depends on the brass and the chamber I believe. As I have had to run to an estimated 42,000 cup to get some formed fully on the first firing.
In reality, there are no set rules as to what works best. Each situation has it's own set of characteristics.

Dave

 

[jtoews80]

I used 7mm Rem Mag W-W cases necks turned .0015" down, CCI250 preimer, 58 grains IMR4350 & a 120 grain Sierra Gameking BTHP(my 115grn NBT's are not here yet). Shot very accurately, the neck turning seemed to really even the velocities out. I hadn't loaded terribly carefully so I got a few rounds that had high ES, but there velocities averaged 2990, I was breaking in the barrel so the flucuations were caused by the cleaning, once I had fired enough to shoot a 3 shot string things improved right away. I had 5 shots in a row come between 2985-2997FPS which is great for ES.

CC.