Methods of Work: Swaging with Heavy Walled Jackets

[Zbench]

Some might remember a thread I posted last year about drawing jackets from Strip. I have been using and enjoying that tooling set for the past year, and thought I would post a thread which shows how some of those heavy jackets can be used. The thread below is sort of a "how to" thread which shows some of Corbin's tooling in use. Many probably look at his website and the stuff he sells there, but it always left me wanting as there is very little of it shown in action. In this thread you will see some of that.

The object is to make 500 grain and up .50 caliber bullets. These are actually .500, not .510. They are for use in the new Bighorn Armory.50 caliber autolader which you can see here

The first step is to make the core and trim the jacket. The core is 292 grains made from .365 wire I extruded and swaged to yield .370 cores. The jacket was trimmed in a pinch trim die. The preswaged assembly can be seen here:




I wanted to put a boat tail on these bullets for a bunch of reasons, but mainly because for heavy bullets they are more accurate. Here you can see the core and jacket loaded into the BT1 die ready to get swaged:




Since these jackets are .065" thick, it takes 1600# of dial pressure to get the jacket to expand and seat the core. It actually takes three hits from the press to get the kind of definition you need. Further, since so much pressure is required, you need to use an external punch which prevents the lead from squirting past the punch or rupturing the jacket. This takes a lot of trial and error to get the right core and jacket length combination. The result can be seen here after being processed through the BT1 preform die:




The bottom of the swaged bullet:




And the top:



Next is to finish the boat tail using the BT2 boat tail finish die. It puts a sharp ring on the boat tail which is similar to, but superior to ordinary boat tail designs. According to Corbin, the sharp ring diverts the gases at right angles upon exiting the bore and it makes the bullet more accurate. The tooling that does this is shown here:




As before, it took multiple hits inside the BT2 die at 1600# or dial pressure to get the boat tail finished. It's not as sharp as a thinner jacket would yield, but good enough to get the desired effect:




Next, to help the jacket open up upon impact, I used the "saber tooth punch" which you use in the BT2 finish die. The only difference is you put the bullet in upside down and press the bullet nose first into the die which is opposite it's normal function. The external punch has a mirror image of the boat tail machined into it to press it into the die. Punch shown here:




The result at 500# of dial pressure. Starting to look like a real bullet:

[Zbench]

All that high pressure comes at a cost in that it makes the finished bullet very close to final diameter. The result is that the bullets needs to be run through a Bullet Reducing die to get the bullet .001" under final size before it is run through the point form die. Otherwise, it would hang up and deform the hollow point. Shown loaded and ready to go below. The punch has the boat tail shape machined into it and it sits on there perfectly:



Through the other side:



Last is to run it through the Point Form Die. I opted for one of Corbin's synchronized honed ejector set ups. The main difference between that and a regular PF die is that it uses a metal probe to define the Hollow point and push the bullet out of the die. It is not pressure sensitive as it is essentially a blind hole, not like the wire affair which can allow lead to flow into the ejection hole. After using this die, I will never go back to the other type of die. Tooling shown here:



Ready to get swaged for the last time. Using 1000# of pressure to get the hollow point defined and nose filled. As before, the external punch has the Boat Tail Shape machined into it:



After ejection, sitting as pretty as you please on the hollow point punch:



The finished result.. You will notice how the lead flowed back into the cuts made into the jacket by the saber tooth punch:





Taper Crimped and ready to kill most anything needing killed:



There are reports that you can lauch a 700 grain bullet out of this rifle. I'm planning to work up a 700 grain pill next. Hope you enjoyed the rundown.

[uncle dino]

Z. A little something to think about when running at higher pressures.. I run an additional split 1 1/2" nut on the underside of the external punch holder, to lock those threads in top plate..A single nut on the holder will cause wear in the head plate and threads become loose. It's only an issue when you run at the higher pressures. I wore out 2 top plates.. Haven't had any issue since I added the additional nut..d

[NoZombies]

Very cool projectiles you're making there, and thanks for the photos. I agree, Corbin's site has a lot of information about his equipment, but is a little thin on the actual process.

I don't have any Corbin dies set up for defined length punches, but have them for other systems, and I'm an absolute believer. I find they provide more consistent HP's, better point definition, and easier ejection.

[nun2kute]

Fantastic "Z" !!! Is that a CSP-2 ? or a Hydro-mite ? I Have kicked the boat-tail idea around for a 458, but not sure it's worth the money for a 200 yard gun. (maybe for my 308) But that saber tooth punch and a hollow point punch would do wonders I think. Any time you want to post more pictures of your methods and means, Don't let me stop you ! I can't get enough either ! Beautiful projectile and cartridge you have there !

[Zbench]

Thanks Nun2Kute. I make all my stuff on the CHP-1 Hydro Press. Its the one in the free standing cabinet. I do plan to make a bullet just like this in 458. With the jacket draw kit I got, I have a draw die to make heavy wall .458 style jackets. I'll use the same process to make heavy 500 grain or so bullets for the 45-70/90 and even 458 SOCOM for subsonic use.

Will post more when that comes to pass.

[BlackoutBuilder]

Yep. Not enough info there. Great job on those bullets.

[PaulG67]

Excellent post Zbench, very informative. thanks.

[marten]

It puts a sharp ring on the boat tail which is similar to, but superior to ordinary boat tail designs

Translated: It is impossible to make a punch to swage the boat tail without the 'ring' in this system.

[Zbench]

Translated: It is impossible to make a punch to swage the boat tail without the 'ring' in this system.

Interesting perspective if it were true. As you can plainly see in the production sequence above, to get a "traditional" boat tail, one only needs to proceed to point forming after the use of the boat tail preform die. The preform die puts the boat tail shape on the bullet without the ring. You can read the merits of the annular ring supplied by the second die here: http://www.corbins.com/rbt.htm Scroll down to the section "Why doesn't everyone use RBT"

[Wolftracker]

Very informative Zbench! I prefer the RBT over standard boat tails. You get close to the ballistic profile of regular boat tails with less throat erosion (theoretically anyway) and I've found them to be just as accurate in most cases.

[Zbench]

While the 500 Auto Max is still not here, I got another set of dies to make bullets in .510 for my 50-70 Sharps. These use the same heavy walled jackets. Shown is a 550 grain bullet ready to go. It has a DEEP 1/2" hollow point that is 1/4" wide at the top. Can't wait to shoot these, will report back after some range time. I made some boat tailed bullets too, going to do some side by side accuracy comparisons.

[BlackoutBuilder]

Those are some pretty rounds.