Making My Own 8mm Jacketed Bullets

[j0e_bl0ggs (deceased)]

1st or taper, 2nd, then plug (bottom).


Yayyy getting there.... cough, locknut?

[22hornet]

Great going again Paul. Still watching this thread with great interest.

But I thought a plug tap was a bottom tap? At least that's my training. Maybe it's a twisted US / English thing?

[drinksgin (deceased)]

Our catalogs list the 3 types as ;
taper, plug and bottom.
I go through a lot more bottom taps than the other 2 types.

[gitano]

At least that's my training.

Remember, I've had NO training. At least none formal.

I'm just repeating what I've seen in the sales literature. I'd think a 'plug' tap was a 'bottom' tap too. Regardless of the terminology, I think everyone understands what I was up to.

When I think of lock-nut, I think of something acting on an 'outside' object; like the lock-nut on a reloading die acting on the press, not on the die. When the 'locking' is on the 'inside' or acting only on the object within itself - as in"capturing" something like the floating punch - I think "capture". Lock-nut/capture nut - pick your poison.

There's no good reason not to be accurate/correct with technical terminology unless there is disparity in 'convention'. For example, the "imaginary" operator in math is "i", while in physics, the exact same imaginary operator is "j". People actually argue about that. It seems reasonable to me to use "i" when one is discussing purely mathematical matters, and "j" when one is describing physical relationships.

While I don't "like" the misuse of the term "accuracy" in the place of the correct term "precision", and likewise "caliber" instead of "chambering", I can "live" with either of those two malapropisms as long as there isn't any confusion in the communication.

It is quite likely that I will continue to butcher machining terminology, and am perfectly fine with being corrected. One cannot learn if one is unwilling to be taught.

Paul[/SIZE]

[gitano]

Now I have to await the arrival of a 57/64ths core drill to rebore the ram so that it will hold the bottom punch at the appropriate depth relative to the die. TARNATION! All this "just one more thing" has got me spitting nails. I shoulda been making bullets months ago!

Oh yeah... Got the little pointy plastic tips. Have to make some bullets so I can use them.

Paul

[j0e_bl0ggs (deceased)]

Yep, probably was not clear, lock nut for Floating Punch Holder body!

As to tap nomenclature plug/bottom is the same thing  (at least here it is).

Taps usually come in 3 types – usually as a "set", starting a first cut, middle  or 2nd cut and lastly a bottoming or plug tap. 1st cut has the most  taper and is design to start the thread in a new hole, 2nd has a bit  less, bottoming will cut threads all the way to the bottom of a blind hole.

Have no problem with you 'butchering' the terminology   :D

The essays teach everyone...  keep it up!

[gitano]

lock nut for Floating Punch Holder body!

Ah so... Gotcha!

I thought about it, but probably will not do it unless it becomes necessary. Bigger pain in the butt than the FPH was. Have to find 1.5" stock, inside thread, cut to reasonable thickness. The fit of the die in the press is snug, so unless some problem arises due to no lock nut on die, I'll leave it as it is.

Paul

[gitano]

I forgot I could just ORDER hex nuts. So... I ordered three 1.5-12 hex 'jam' nuts from Fastenal. http://www.fastenal.com/web/products/detail.ex?sku=36277 I will use them 'as-is' or maybe 'split' them and get two-for-one if it seems reasonable once I have them in hand.

I mounted the press to my former reloading bench. (Recall the renovated reloading room.) The weight of the press meant that I had to strap the bench to the wall. This press really is at least 1/3 'over-built'. By that I mean that ALL of the square stock could be reduced in thickness by 1/3. Possibly even 1/2. The round stock should remain the same as they are now. The ram because of the dimensions of the dies and their associated components, and the guide rods just because there's no need to reduce their diameter.

Paul

[gitano]

I also need to make a core cutting device. You can see j0e_bl0ggs' here http://thehunterslife.com/forums/showthread.php?t=16328&page=6 at post 57, and here http://thehunterslife.com/forums/showthread.php?t=16328&page=4 at post 32.

I went looking for square stock at the local Home Depot, and the biggest they had was 5/16ths. The core of the 8mm bullets I will be making will start at 0.250" in diameter, which would leave only 0.031" per side. (0.3125/2) - 0.250 = 0.03125") I have some 3/8ths thick plate that I may make into a 'scissor'. I'm working on the design of the 'depth gauge' part of it now.

Paul

[gitano]

So... in anticipation of making the core wire cutter, I thought I'd do a little number crunching to help with the design.

Here's an Excel table I generated to estimate the length of quarter inch lead wire I would need to cut in order to make a 125-grain bullet with the jackets I have on hand. You might want to look at  post #1 in this thread to re-familiarize yourself with these jackets.


As you can see in the table, in order to get a 125-grain bullet, I'd have to have a core of length 1.5 cm. That's a bit of a problem since the depth of the jacket's core is only 1.4 cm. (You'll see the dimension in the first post in this thread as 0.560". That equates to approximately 1.4 cm.) A core of length 1.5 cm would have the lead projecting out from the mouth of the jacket - an "exposed lead spitzer". In the "grand scheme of things" that's not a "bad thing", but in this specific endeavor - making an open hollow pointed bullet - it most certainly is not "good". HOWEVER...

The target weight of 125 grains was a VERY casually chosen value. I really didn't want to have to go up in weight over 130, but I'm just fine with going down in weight. Remember, this bullet is by design supposed to be LIGHT for caliber.

Another thread to read in the context of this whole project is this one: http://thehunterslife.com/forums/showthread.php?t=12747. In it you will find some pictures of the bullets I am trying to emulate - the Speer 7mm 115-grain HP and the .30 caliber 130-grain HP. Both have large, OPEN hollow points.

The depth of that "open" hollow point is 0.20" in both the 7mm and the .30 caliber bullets. Interesting - at least to me - is that the tenon on these add-on tips http://www.midwayusa.com/product/347096/cutting-edge-bullets-esp-raptor-bullets-talon-tips-338-caliber-polymer-bag-of-25 is also 0.20". Therefore:

1) If I want to truly mimic the Speer bullets, and
2) If I want to use the plastic inserts,

I will want to have the core of my finished bullet be back 0.20" from the mouth of the hollow point of the jacket. 0.20" translates to 5.08mm. Here is the reworked table showing the core weights if the core is shortened 5.08mm.


So I have to reduce the length of the core by 5.08mm. Since there is about 5.55 grains of lead in a .25" diameter lead wire that is 1mm in length, that 5.1mm reduction in length will mean a weight reduction of 5.1 * 5.55 = 28.3 grains. From the new table that includes hollow point considerations, I get a finished weight of almost 92 grains. THAT is certainly LIGHT for caliber! I actually expect the weight to be less because the core will get 'pushed forward' a little bit when the ogive is formed, and I will therefore have to shorten it even more  than the 5.08mm.

I think there will be some 'fiddling' required to find the "sweet-spot" between final weight and finished core dimensions.

Paul  

[j0e_bl0ggs (deceased)]

What is the dimension of the swaged lead core?

[gitano]

Hmmm....

So I went to my ballistic coefficient (BC) calculator and 'crunched some numbers' with a 90-grain, 8mm, open hollow pointed bullet. The news was "bad". Weight has a big effect on BC.

The BC of that bullet is only .165. Started at 3700 f/s (from QuickLoad calculations) at 300 yd, impact velocity is only 2000 f/s and impact energy is only 800 ft-lbs. If I put a plastic point on it which ups the weight by 4.34 grains, the BC goes up to .270. Which in turn changes the 300 yd ballistics to 2602 f/s impact velocity and 1353 ft-lbs of impact energy. Those are BIG improvements. Looks like I may be forced to put plastic tips on these bullets.

The differences between m bullet and Speer's derives from the thick jacket on mine. It is just over twice the thickness of the Speer jackets - 0.015" vs 0.035". Therefore there is a considerable loss in weight due to the differences in density between copper 'gilding' and pure lead. Also, my jackets are only producing a finished length of about 0.6" whereas the Speer bullets are 0.9" long.

This is going to be interesting.

Paul

[gitano]

What is the dimension of the swaged lead core?

Before inserting in jacket?

Paul

[gitano]

Here's the problem that j0e_bl0ggs was getting to: The core diameter of the core swaging die is 0.250" meaning that the sized core will be 0.250" in diameter and whatever length the die setup is set to. However, the core SEATING die is 0.2945" (see picture in post #23 of this thread). The inside diameter of my jackets is 0.253"! The core seating punch - the 'thing' I made the floating punch holder FOR, won't fit inside the walls of my jackets. "Regular" factory jackets are about 0.015" thick or less. My jackets have 0.035" walls. More than twice as thick. Therefore, the core seating punch will not work.:angry: ANOTHER 'thing' to deal with before I can make bullets. HOWEVER.

In the end, this will force me to make another core seating punch, and I can make it specifically to form the "hollow" in the core that will accept the plastic tip. This will hold the tip better and, probably allow me to increase the overall weight a little bit. I would be very happy at 105 grains as a finished weight.

I can make the new core seating punch while I'm waiting on the 57/64ths core drill bit.

Paul

Oh by the way.... I can get a 95 grain bullet going in excess of 4000 f/s at the muzzle from an 8mm Remington Mag cartridge. :D:D:D

Paul

[j0e_bl0ggs (deceased)]

Iron out them wrinkles then good to go!
Was thinking about the plastic tip... might be better to form the point 'around' the insert on reflection...
Need to work out the dims for the insert stem part of the punch.
I do not thing that much 'point forming' will be going on as the base of the plastic tip was a quite large ø.
This should be quite an interesting bullet and performance well 8mm mag +4kfps...wow!