Some questions about jackets.

[Alberta_Steve]

I have a couple questions about jackets.
I know Corbin's are undersized and when you seat the core they expand to final size. Are other brands like j3 or center-x the same?
If you want bonded bullets for hunting you would seat the core and size it then bond them? (With Corbin jackets) It seems to me like you could skip this step if the jacket was already the correct size?

(Hopefully this format is legible I am posting from my phone and not sure what font size to use)

[rolltide999]

All jackets must be undersized so that you are always "swaging up" to size in the core seating and point forming processes. This is necessary to make the seated cores and final pointed bullets release from the die due to a minute amount of spring-back in the bullet being made. Otherwise you will end up with bullets stuck in your dies.

When you are making bonded bullets, you place the swaged or molded core in the jacket with a drop of bonding agent. Then you melt the core in the jacket with a torch or in an oven. The core is chemically bonded to the jacket in this process. The bonding agent is corrosive, so if it is not removed, it will destroy the swage dies used to finish the bullet. So you then boil the bonded cores and jackets in water and baking soda to remove/neutralize any residual bonding agent. You then seat the core and point up the bullet as with unbonded cores.

I hope this is helpful.

[bigjake]

All jackets must be undersized so that you are always "swaging up" to size in the core seating and point forming processes. This is necessary to make the seated cores and final pointed bullets release from the die due to a minute amount of spring-back in the bullet being made. Otherwise you will end up with bullets stuck in your dies.

When you are making bonded bullets, you place the swaged or molded core in the jacket with a drop of bonding agent. Then you melt the core in the jacket with a torch or in an oven. The core is chemically bonded to the jacket in this process. The bonding agent is corrosive, so if it is not removed, it will destroy the swage dies used to finish the bullet. So you then boil the bonded cores and jackets in water and baking soda to remove/neutralize any residual bonding agent. You then seat the core and point up the bullet as with unbonded cores.

I hope this is helpful.

So, the flux is an acid type right? Can rosin flux be used? it is used in electronics and i assume it doesn't corrode.

[SSG_Reloader]

Yes all jackets are slightly undersized for the caliber they are meant for. This will apply for all jacket makers. Just a couple quick measurements of some .308 jackets:
CenterX- .3065
Richards Corbins- .3062
Dave Corbins- .3063
J4- .3065

On a side note, does anyone know if CenterX actually makes their jackets? I thought I heard he was just a reseller. I could be completely incorrect on that.

As stated above 1. Bond 2. Clean 3. Seat 4. Point form

[SSG_Reloader]

I've also been able to Swage .264 from jackets that are much smaller than their final diameter. .255 copper jackets and .242 brass jackets I make from 22 mag brass bump up just fine to .264.

[MFG_BOP]

the owner of center-x told me, for the 50BMG, he buys them from a third party company. i don't know for the other sizes

[rolltide999]

@bigjake
I have never experimented. I just use Corbins bonding agent. Their web site says it is used by many commercial bullet makers, although Corbins website tends a little toward self-promotion, so take that for what it's worth. Theirs works and is reasonably priced and 16oz will probably last me a lifetime. It only takes a drop in the jacket with the core.

[Alberta_Steve]

Thanks for the all the replies and the info I was actually wondering the exact size of .308 so that helps a lot. If you are using copper tube for jackets with a thicker wall you would make them that size right?

[rolltide999]

Yes, I have tubing jacket makers for about 10 different calibers from .510 to .308. The outside diameter is undersized just like the commercial jacket, but you do need special made (smaller diameter) core seating punch for the core seating die, and possibly a different core swaging die depending on if the swaged core is small enough diameter to fit in a jacket with jacket walls twice as thick.

[SSG_Reloader]

Correct. Since 5/16 tubing is larger than the diameter you need, you'll have to draw it down to about .306ish as well and it's definitely a thicker wall. If you're making jackets from something like 3/8, you'll have 2 to 3 draws which also affords the opportunity to thin the wall out slightly as well depending on your punch diameters vs the draw die diameters. Some jacket maker sets have set punch length when rounding the end so you would need various punches correlating to the desired length. As an example, I've got 4 punches for 4 length options of .308 with my BT Sniper set so I can Swage as low as 110gr for supersonic 300 blackout all the way up to 230gr for subs, plus various weights in between for .308 and 30-06. I've also got some Corbin jacket makers which have adjustable punches that give you a limited range of jacket lengths you can make for a caliber. These allow you to adjust and fine tune jacket weights within reason. I experienced exactly what Rolltide is talking about with requiring a new core Swage for .338 from 3/8 copper tubing. Unfortunately my BTSniper core Swage didn't come close to being able to use for either commercial jackets or the copper tubing I sent to build the jacket maker set around. An extra step of drawing down the core itself is required unfortunately. Copper tubing jackets can be a bit more work but are worth their weight in gold when their are projectile dry spells.