375 mold to bore out to take a 3/8 in tube for a jacket

[Welding Rod]

Picked up a project mold. One cavity has a ding on a driving band near base. It is a older NEI 375 320 gr. I figured its just a 1 cav mold now but thought about boring out the lube grooves on the bad cav to take a piece of 3/8 in copper tube. Not an original thought read about it somewhere and it worked well. Might have been a Paco article. Has anyone tried this. Have to get some tubing cut and see how the dia comes out. I guess I could run it through a push through die to make it round and consistant dia.

Any thoughts?

Thanks, Rod

 

[Brad]

I can remember years, or rather decades, ago seeing an article where a guy had a mould set up for a similar idea. He used rings cut from copper tubing for driving bands in a mould. If I recall correctly it worked well but he found it to be rather fiddly to work with and discovered one best use pliers to add things to a hot mould. Seems his fingers grew weary of getting burned.

Go for it but please let us know how it works. And we gotta see photos. This is a neat idea, if not overly practical.

 

[300BLK]

There was an article in one of the magazines back in the 70s about such. I don't recall the caliber, but the bullet profile was like in Brad's avatar. Tubing was cut to length, inserted into the hot mold, and the core poured. I would think the tubing would need to be cleaned, preheated, and possibly tinned on the inside so as to have the core solder onto the copper.

I've been looking at those silly 5.7x28 cases that I find at the range on occasion and keep thinking that they could be 30cal jackets.

 

[Welding Rod]

I think I'll ream out the mold up to the crimp groove. Measure for tubing length. Cutting the tubing was the part I had not figured out. A tubing cutter leaves a nice ridge on the inside that would hold it to the core. Keeping length consistent was puzzling me a bit, till I posted this then the little idea light bulb lit up. I will turn a piece of round stock to fit inside the tube put in mini lathe and mark my cuts with a cutoff tool. Lathe has a DRO, EASY. Remove from lathe then cut with tubing cutters so I cut the tube with ridge on the inside to lock the core. Run jackets through size die to make uniform. Clean them on inside. With the ridge from the tubing cutter I think I could skip the tinning step. It would bond the core to the jacket so I'll try it. I will try them warmed on the hot plate. Just slide into mold and fill. Seems easier than swaging definitely cheaper.

Brad
The idea of rings does not seem practical, This is one piece like the half jackets for swaging, but without a bottom.

 

[blackthorn]

Any way to use a 380 case instead of the copper tube?

 

[300BLK]

.380 cases might work for a nose pour design. 38 Supers and 9mms might be swageable.

 

[Ian]

I don't know many people in "modern" times who have done this. It's a neat project, I think you should go for it. Pre-heating the jackets will tend to oxidize them, not sure it matters, but putting cold jackets in there might cause bonding and fillout problems due to sucking the heat out of the lead stream as it's poured through the tube.

 

[Pb2au]

This thread tugged at a memory I had of a video along these lines. Took me a bit, but I found it.

 

[Welding Rod]

It is a bottom pour, the reason to use copper tube is it strong, ductile, and its a bottom pour mold. Jackets will be warm 350-400, copper is fine at those temps. I figure I'd preheat in the oven put on hot plate and go...

Mold is NEI 320375GC It is not in Catalog. Jacket will be about 0.63" LOA 1.23" Meplat 0.16"

 

[fiver]

I done this to a lyman 180gr 30-cal spire point mold.
it's pretty simple to do.
sizing them down is something you'll wanna do in a LEE push through die. [it will break a STAR sizer]
you'll also want to heat the jackets on the edge of the pot before inserting them in the mold, and tap the top of the sprue plate after closing it.
one more thing you'll want to do is cut the jacket hard with the cutter and leave the ends rolled over to lock it to the core.
I sized the jacket before casting through it and left the cast bullet at diameter after learning the hard way the first go round.

adding a cannelure to the jacket part will help stop expansion right there too.
Little girl and my oldest girl still use these in their 7.65 argie and 7.7 Jap rifles sized to 312 for deer hunting at about 2100 fps.
a high shoulder shot at @ 100 yds or so will flip-flop a deer so fast you'll lose it in the scope.

you want to use soft tubing, or the straight hard rigid 3/8" water pipe version, which airc measures about 380 [have some in the back-yard for just this purpose]

I ordered a whole 50' roll of tubing from a plumbing supply store it was about 1$ per foot, but a foot gave me 24 jackets [cut to .474 long] cost effective enough to make it worth while.
the initial trial tubing I picked up at ACE hardware for a little more money.
I made a little JIG from a piece of 1x4 and a couple of hose clamps to hold everything straight and just marked everything with my calipers locked into place.
my oldest girl cut most of the jackets after I showed her what to do.

 

[KHornet]

Many years ago, when I was just a kid, I knew a guy who had one of those molds for 30 cal, and he had bands that fit (it seems like the bullet was heavy like a 311284). Seems like I remember that he called the projectiles Barnes Banded Bullets. I also remember that each bullet had 2 bands of copper. He shot them in an issue Krag. He said they were tough to cast because of having to putt the bands in the slots with needle nose pliers. He was an older gent, probably in his late 60's or early 70's and is long gone now.