I am getting to the point where I am exploring paper patching and thought of the possibility of vacuum forming plastic "jackets" around the bottom of my cast bullets.
Has anyone here tried this?
I am thinking that if trimmed at the start of the ogive and perhaps slit in three or four places like a sabot, they would shed as they exit the barrel as a paper patch should.
Any thoughts?

I'm thinkin' that with the pressure, heat, and friction factors, the plastic would melt into a nasty mess.

I was wondering about that too.
I know some plastics are usable as sabots such as the accelerator type which are used to shoot .224" bullets in 308s etc.
Now, whether these plastics can be bought in sheets and perform without problems in the former and the bore is another matter.
Maybe someone here has a plastics engineering background.

Shotcups work fine for slugs!
On the other hand i have a 50cal SLAP that is tough as nails. 12 yrs as a keychain and it almost looks new.

i have seen plastic used for cases for the 38 special and for the 223.
they aren't subjected to friction like a bullet would be.
but if you had a bore diameter projectile and a groove diameter jacket, even if they stayed together, it could work.
the plastic would have to be soft enough to be engraved by the rifling but hard enough to withstand the pressures.

Hey Huvius, There used to be a guy who posted here as "Sabot"(maybe, not sure now). I thought he might have responded to your thread, but he might not be an Active Member any more.

You could see if he would respond to a PM. He might be able to tell you what Plastic Materials would be suitable for Shrinking or why it would be a mess as Craigster mentioned.

Obviously some Plastics will work as Sabots at High Velocities since there used to be a Saboted 22cal bullet available in a 30-06. But it was Injection Molded, not a Shrink style Plastic.

You might try Plastic Shrink Tubing for Wires, but getting the thickness consistent might be a trick. But, it might be a mess.
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303guy is doing a lot with Paper Jackets right now and I know he would be glad to share his experience with you about them. Once the Load is Developed, they tend to "Polish" your Bore with each shot.

I met a guy at the Range shooting a long barrel single shot Browning(maybe a B78???) in 45-70 using Paper Jackets on (I think) 500gr Lead Slugs. He told me he was getting around 2100fps with them. I walked away and thought about it a bit and went back to see if I'd heard him wrong. That is 458WinMag velocities. He said it was easy to do with the Paper Jackets without Over Pressure conditions.

Plus a look in his barrel and it appeared that it hadn't even been fired. Very clean and highly Polished.

Best of luck on your project.

I sure hope you do it and report back. I had the same idea about 10 years ago, and went so far as to have some in depth conversations with outfits which make both vacuum and extruded plastic products sold world wide. I even designed both such a plastic jacket, and a bullet it could snap" onto. (Bullet moulds were then generally about $100 or less at retail price, even for custom ones.)

But, when I found out the prices of dies for vacuum forming or extruding plastic jackets, or even plastic gas checks, I decided I'd give the rest of my money to Hornady (as needed) for their Lubaloy" G-checks. I also went out and purchased about 200,000 Hornady GCs at the average then current wholesale prices of about $7 per thousand, so haven't needed to give them any more money yet.

As a business venture plastic do-it-at-home jackets might pay off if offered as a new product, to an exisiting customer base of an already established gun business. But, being well into my mid-70's, I'm absolutely not interested in the least in going back into business. Hell, I hardly have time to brush my teeth each day now.

Anyway, hope you go for it and get back to us all here.

Best wishes,

AC

My best suggestion is to design either a gas check or sabot and make friend with a someone that works in a plastic injection molding outfit.
They may have an existing tool they can add your design. This will permit them to mold your part at the same time as another part costing them basically nothing since the amount of plastic involved is so small.
Just besure to research and find the proper plastic for the application.

I doubt that you would even want to spend the $$$$ to build a injection mold, much less the press time $$$$ and nylon cost to actualy shoot the parts.

I will give you a quick quote for a small mold

A 5x5 M.U.D unit 4 cavity mold would be lowball $3500 for a down a dirty P-20

Actually, I am invisioning forming right over the bullets themselves.
As a kid, we made bodies for remote control cars by vacuum forming over wooden bucks in Tech Arts class.
I have done a cursory search online and see there are flame resistant plastics which are compatable with this method.
Now, whether a consistant thickness can be achieved will have to be seen.
Have any of you paper patchers ever found and looked at the shed patches from your shooting?
What type of charring is there on the base of the patch? Maybe the paper from the base is totally burnt!?