Reforming load?

[blaser.306]

Looking for a load to fire form resized .308 to 7/08 dominion brass using 135 gr lee g/c boolits and red dot!

[Wayne S]

If ypu have a bolt action rifle and are starting with new 308 brass what I would do is run the brass through your 7-08 sizing die untill about 1/2 of the 308 neck has been sized down to 7 MM.
Try to chamber this case, if it wont't chamber, lower your die maybe 1/4 turn and try again.
The object is to size the case till it will chamber but with force, what you are doing is setting a false sholder on the 308 case's neck.
I don't have a working knowledge of red dot but by setting the false sholder you could load what you plan to load with the Lee bullet anyway.

[Shiloh]

Not knowing a lot about fire forming, can it be done successfully with cast boolits??

That is, are the pressures high enough to get the job done??

Thanks in advance for the education.

Shiloh

[madsenshooter]

Unless you're talking about some sort of wildcat 7/08 with a different shoulder angle, there's no fireforming involved. Just full length size the 308 down to 7/08 and use your usual loads. In my Krag, I've noticed that it takes about 35,000psi to get the case to properly seal. That's a 20gr load of Blue Dot behind a 169gr boolit. It does a good job of blowing out the upper body of .303 British brass to fit the Krag chamber.

[Wayne S]

Check a reloading manual for differences in a 308 case and a 7-08 case drawings. The length from the case head to the top of the shoulder in the 308 case is 1.711, in the 7-08 it is 1.751 or .04", not much but the case has to streach from sonewhere.
Just like forming Herrett cases if you set them up with a false shoulder for head spacing on before fire forming you get longer case life.
It's up to you

[badgeredd]

My experience with fireforming cases is to use a normal load of medium burn rate powders in rifles. I personally wouldn't use a fast powder like Reddot. The false shoulder idea is a good idea to ensure your case isn't driven forward during the initial forming although for this particular cartridge it may not be necessary. I always go with a false shoulder just to be sure, but that's me. I had trouble with the first batch of 6MM TCU I formed because I didn't have long enough bullet to engrave the rifling and didn't use the false shoulder idea.

Edd

[blaser.306]

I am already doing the "false shoulder" on these brass . I guess that I will just use some of the IMR 4198 that is listed in the Lyman cast manual , The reason I ask is I have a 23 lb keg of red dot made in the 60's and several hundred of the lee cast 135's that don't shoot accurately but don't want to wast the gas checks IE: perfect slugs for fire forming . I have also been told to just use 3 grains of bulseye and fill the case with (cream of wheat) then cap it off with parafin and let er buck !! Personaly I like the shooting idea better . The loads will be getting worked up for a Wichita arms Silouette pisol in7/08 (obviously) cant wait till spring comes and I can try these at the Silouette range . Thanks for the replies, Barclay !

[fatnhappy]

Check a reloading manual for differences in a 308 case and a 7-08 case drawings. The length from the case head to the top of the shoulder in the 308 case is 1.711, in the 7-08 it is 1.751 or .04", not much but the case has to streach from sonewhere.
Just like forming Herrett cases if you set them up with a false shoulder for head spacing on before fire forming you get longer case life.
It's up to you
but the datum line of the shoulder is the same. The difference in distance is only due to the difference in diameter of the neck. I've been using 7.62 nato brass and commercial .308 cases necked down for both my 7-08s for years. All you need to do is FL resize in a 7-08 die and have at it.

[12glocks]

It's been a few years but:

I annealed the necks first. Fl resized and shot. The OAL of the case will be a little shorter than factory 7-08.

[405]

As has been posted the best way is to size to a false shoulder to ensure best headspace control. Otherwise case stretching ahead of the web may be hidden thus shortening case life. Use a medium powder- red dot isn't it!. The most complete fireforming will happen at about a 30,000 psi threshold, as has been posted. Of course those pressures or more may mean a strong bolt gun.

[Shiloh]

What about multiple firings?? Whit new Krag brass, The first firing had soot on the cases. No soot or very little on the second, nothing at all after that.

Shiloh

[Tom W.]

Not knowing a lot about fire forming, can it be done successfully with cast boolits??

That is, are the pressures high enough to get the job done??

Thanks in advance for the education.

Shiloh


I use cast bullets to fireform my 30-06 A.I. cases using moderate loads of IMR 3031

[405]

Shiloh,
Your question about using cast for fireforming/reforming is maybe? To get full fill out of case to chamber specs in all dimensions you need about 30,000 PSI or more. Lower pressure cast loads will do it partially. But "partially" doesn't really get the job done. The troublesome dimension for any fireforming is the headspace dimension. Obviously for rimmed or belted cartridges no big deal at all. Just enough pressure to swell out the walls of the case. But for those cartridges that headspace on the shoulder datum ring..... that's where the bugger is! I've tried it many ways for several different cartridges.

Bottom line: if there is readily available brass that is correct for the chambering then usually it is MUCH easier and the correct case is much better than trying to save a relatively small amount of money by trying to change a case to something else. The other down side to changing the case (not often mentioned) is that the original headstamp is still there on the now WRONG case. Certain mix ups in the future won't do much other than split a neck and send a wobbler out the muzzle. Other mis-matches can be costly!

For fireforming one of the shouldered cases using cast it's a matter of pushing the shoulder outward and forward, filling and pushing against the chamber shoulder ..... not stretching the case rearward..... the headspace bugger! To do it right requires the higher pressure of about 30,000 psi or more and the case has to be held tight against the breech block/bolt face during all parts of the firing sequence. Amazing how much force is exerted forward by the primer impulse at ignition. So a hard cast bullet needs to be seated forward in the neck and crimped well. When the cartridge is chambered the bullet is forced hard into the lands.... preventing that forward thrust of the case at ignition. This keeps the case base tight against the breech block and as the firing pressure rises the shoulder area is forced outward and forward creating the new correct headspace with that case in that chamber.

If anyone doubts all this just try shooting some low pressure cast loads using a shouldered rimless case that has a short headspace dimension compared to the chamber in which it is fired. Without exception it will show a popped back primer. That case is not fireformed and the excessive headpace in that case remains. Firing it again in that condition with a normally seated bullet with the higher pressure will show the primer back in its pocket but what is not seen is that the case has stretched rearward thinning the case walls just forward of the head.... no mystery that is where case head separations happen at some point in the future of that case.... maybe sooner rather than later :(