Making My Own 8mm Jacketed Bullets

[gitano]

So.. There was - as expected - another 'wrinkle'. If you look at the pictures above of the core seating punch, (the punch for which the Floating Punch Holder FPH was made), you will see that the 'business end' of that punch is 0.2945" in diameter. That punch was made by Corbin for "regular" bullet jackets whose wall thickness is no greater than 0.015" and closer to 0.010". If you subtract 0.028 (two times 0.014) from 0.323 (bullet diameter in inches) you get 0.295". That punch fits inside a "normal" jacket. My jackets are not - by design - "normal". They have walls of 0.035" thickness.

As I pointed out above, if you subtract 0.070 (two times the 0.035 wall thickness) from the bullet diameter - 0.323 - you get 0.253. Making quarter inch lead wire (0.250 nominal) just about 'perfect' for the core material. Unfortunately, that means that the Corbin punch that has a diameter of 0.2945 is too large to work with my jackets. I had to make another core seating punch.:frown:frown:frown:frown:frown (That's as close to cussing as I can get on THL.)

So here's the new punch (0.255" in diameter in the 'business' end) that I just completed, beside the Corbin punch.


As usual, there is a silver lining on this cloud. I now have the confidence to make any of the other punches necessary for swaging bullets. Now the only thing left for me to get comfortable making are the dies. I don't think I'll have a problem with the core seating die. The core swaging and pointing dies will be more of a challenge.

Paul

Oh yeah, I had one of my jackets in hand when I made the new punch, and it fits on with 0.001" of "slop" on each side.

[gitano]

Voila' - Sort of. Swaged, but not in the press designed for this. However, it was in the dies I will be using.



116.9 grains
1.071" long
Ballistic Coefficient - 0.305 at 3500 f/s

If launched from the 23.25" barrel on the 8mm SLT, 3500 f/s MV is easily attained.
At that MV:

300 yd Impact Energy is 1543 ft-lbs.
300 yd Impact Velocity is 2438 f/s.

Trajectory with scope settings for the 8mm SLT and allowing bullet to go 1.5" above line of sight:

100 yd: +1.2"
150 yd:  +1.5"
200 yd: +0.8"
225 yd: +0.0
250 yd: -1.0"
260 yd: -1.5"
300 yd: -4.1"

If this 'thing' hits where I aim it, it should have considerably "better" terminal performance than the 115-grain 7mm Speer after which it was designed.

I am pleased with the paper-whipped results - to say the least. :D

Paul

[gitano]

When I first started loading the Speer 115-grain 7mm bullet in my 7x300 Weatherby, It wasn't difficult to get it going 3500 f/s. I decided to take it out to the "range" (back in the woods behind Eielson AFB) and give it my normal terminal performance test - a 1 gallon plastic milk jug filled with water at 100 yd. Just so happened that there was  55 gallon steel drum laying on it's side where I stopped to shoot. I set the milk jug on the side of the drum, backed off 100 paces and 'let fly'. HOLY COW! It bent the 55 gal drum almost in half! The opposite ends were almost TOUCHING! (Think bending a beer can in half.) THAT is serious "shock", or what I call the "hammer effect". I used that bullet in that rifle to take MANY big game animals in Alaska and Outside. They all died without moving more than a body length from the point of impact.

Here's a visual comparison.



Here are the ballistics for that 7mm bullet to compare with the 8mm:

115 grains
0.925" long
Ballistic Coefficient - 0.250 at 3500 f/s

If launched at 3500 f/s:

300 yd Impact Energy is 1431 ft-lbs.
300 yd Impact Velocity is 2352 f/s.

Trajectory with scope settings for the 8mm SLT and allowing bullet to go 1.5" above line of sight:

100 yd: +1.2"
150 yd: +1.5"
200 yd: +0.7"
222 yd: +0.0
250 yd: -1.3"
255 yd: -1.5"
300 yd: -4.5"

Almost identical, but the 8mm technically 'wins' in every category. Then I get to add 0.039" in diameter. :D That's like going from .269 (~6.5mm) to .308. Most folks believe that the .30 caliber "hits" harder than the .264 if both have the same impact velocity. I certainly do.

Oh yeah, I forgot to mention... The jacket on my bullet is more than twice as thick as the one on the 115-grain 7mm. :D This ain't no varmint bullet!

That might be what I call it - The 8mm ANVB (Ain't No Varmint Bullet).

Paul

[gitano]

For those of you shooting 8x57s:

116.9 grains
1.071" long
Ballistic Coefficient - 0.275 at 3319 f/s

If launched from a 24" barrel, 3300 f/s MV is easily attained.
At that MV:

300 yd Impact Energy is 1349 ft-lbs. (1500 ft-lbs out to 260 yd.)
300 yd Impact Velocity is 2279 f/s.

Trajectory with scope settings for the 8mm SLT and allowing bullet to go 1.5" above line of sight:

100 yd: +1.3"
130 yd: +1.5"
150 yd: +1.4
200 yd: +0.5"
214yd: +0.0
246 yd: -1.5"
250 yd: -1.7"
300 yd: -5.4"

That's not shabby...

Paul

[j0e_bl0ggs (deceased)]

Way to go!  8mmANVB
Pat on back well deserved.
Smug smile allowed for the weekend...

Will be interesting to see how much extra lead will 'fit' when using the core seat properly, but then I quite like that radius style 'boat tail'.

[gitano]

Smug smile is wiped off by realizing WAY too late that I made the core seating punch out of 12L14 stock I had laying around, instead of 4140. Bent with first use. While that means I almost wasted the 4 hours I put into it, it wasn't a total waste. The 'exercise' was good. I'll make another out of appropriate steel.

The bullet shown above was seated with a lead core that 'mostly' filled the jacket's cavity. Swaging the point was too easy as there is very little 'squeezing' done when the plastic tip is 0.240" at the point where it intersects the ogive of the bullet. I then chucked the bullet in the lathe and bored a 5/32nd (~0.156") hole in the core, 0.200" deep relative to the mouth of the jacket. I might be able to get another 2 or 3 grains of lead into the bullet were I to choose to "drill" every bullet, but that is NOT the case. In fact, I am thinking of reducing the weight to 115 grains.

The plastic tip is significant with respect to the BC of the bullet. However, I REALLY hate having to install one. MOSTLY because they are 50 cents a piece! Add to that the 28 cents a piece for the jackets and about 2 cents of lead and you have a cost per bullet of 80 cents a piece. That's $80 per hundred. THAT is an expensive bullet, and TWO THIRDS of the cost is the little plastic tip! I either have to get the tip makers to lower their prices (maybe a volume discount) or find another source - maybe self-made.

I'm not rationalizing when I say I "like" the rounded 'butt' of this bullet. Making boat tailed bullets is difficult and expensive for the "hand swager". The reason for boat-tails is to "ease" the turbulence at the base of the bullet, thereby increasing the BC and maybe the "accuracy". While this round butt is NOT a boat-tail, it WILL accomplish - at least to some degree - a reduction in the turbulence at the base of the bullet. That "works" for me.

Paul

[drinksgin (deceased)]

Modified Kamm-back?
What is the plastic, can it be melted and poured, could you stamp it out of Lexan, can you turn it of one of the high density plastics being used for bearings?
Sorry, just a bunch of questions, nothing actually helpful.

[j0e_bl0ggs (deceased)]

Hah! Now make the punch from real steel.
As discussed the ø of the punch above the jacket should slip fit the die, this helps with the 'bending' problem by supporting the punch. Stepped punch is the way to do it!
Anyone here have access to a 3d printer?

[gitano]

While I understand 'what for' and 'why' you suggest a stepped punch, I am not convinced that it is necessary. It:
1) adds complexity to fabrication,
2) decreases flexibility in use, and
3) increases the probability of damaging/destroying the core seating die.

Modified Kamm-back?

I have no idea what you are referring to, Don.

The tip could be turned out of delrin rod, (or any reasonably machined plastic), but turning it would be more expensive than these tips are.

I don't think it could be "stamped", but I could be wrong.

One should be able to "pour" it, but I think "injection molding" would be the better choice in "hot, liquid plastic" methodology.

What j0e_bl0ggs is referring to with the 3D printer is that 3D printers can be used to fabricate small objects. http://www.bing.com/videos/search?q=3D+printer+fabrication&view=detail&mid=32FBE62946B891FF7E8F32FBE62946B891FF7E8F&first=21&FORM=NVPFVR http://www.makershed.com/Articles.asp?ID=301 This plastic bullet tip would likely be an excellent candidate for 3D printing, but;
1) I have no access to a 3D printer,
2) I have no experience with 3D printers,
3) I have no idea how the cost of 3D printing compares to injection molding.

I THINK that the most likely best choice for making these is to contract out to an injection molding house.

Paul

[22hornet]

Awesome looking projectile Paul!


I have heard of guys using plastic Airsoft BB's to make plastic tips. I'm not sure how they make them pointy other than a forming die.

On Castboolits some guys are using ski binding plugs(?) They should be super cheap, might be worthwile investigating......


I am watching this unfold from the sidelines. Sorry I have nothing constructive to add, this is all above my level of expertise.

[gitano]

"Constructive" additions aren't required to participate in this thread or in general at THL, 22hornet. Thoughts help. I had forgotten about the Airsoft BBs. That warrants a look as do the ski-binding plugs, though I don't know what those are.

I'm thinking seriously about asking Nosler and Hornady to sell me some of theirs.

Paul

[drinksgin (deceased)]

Kamm back refers to a German engineer who designed a shape for the rear of a car that reduced turbulence and increased speed, his name was "Kamm".

[22hornet]

Ski binding plugs.

http://www.slidewright.com/plastic-binding-hole-plugs-pk_svpbhp.html
 
Just by looking at the picture, do you think they could do the job?

[j0e_bl0ggs (deceased)]

While I understand 'what for' and 'why' you suggest a stepped punch, I am not convinced that it is necessary. It:
1) adds complexity to fabrication,
2) decreases flexibility in use, and
3) increases the probability of damaging/destroying the core seating die.

1, not really.
2, again, not really
3, where do you get that idea from?

Complexity in reality is 1 extra dimension with the advantage that the punch stem will be a larger ø therefore will be stronger.
The length of the punch that bears upon the lead core can be say 1/8 -1/4 long so will not decrease flexibility of use with this jacket - remembering that you will not be able to use this punch with a 'standard' jacket.
The real advantage is applying the swage pressure concentrically and having support guiding the punch to avoid bending the stem, in all probability it will reduce the possibility of die or punch damage.

When setting these dies you have to sneak up on your finished dimensions regardless of the punch shapes being used - if you don't, well it's only a 2 year wait from Corbin for a replacement!

[j0e_bl0ggs (deceased)]

Awesome looking projectile Paul!
 

I have heard of guys using plastic Airsoft BB's to make plastic tips. I'm not sure how they make them pointy other than a forming die.
 
On Castboolits some guys are using ski binding plugs(?) They should be super cheap, might be worthwile investigating......
 

I am watching this unfold from the sidelines. Sorry I have nothing constructive to add, this is all above my level of expertise.

Airsoft bb's and binding plugs have one small problem, they do not form very well having too much 'spring back' as you will see from the attempts at cast bullets.
I have experience of them and have jettisoned that idea!

Now a home made injection moulder would seem to be the way to go assuming the tooling for the tip can be made - bit of edm machining needed for this fiddly part!
Will ask my bruv if he can get some printed on the 3d printer...