Bullet Casing Questions

[jimm1]

So I have some 30-06 casings that I bought already with the 7mm tube inside. So how come when I try to press the 7mm transmission in, I keep crushing the neck? I use emory on the transmission, I clean out the brass tubes. I don't get it.

I also have some casings without tubes that I get from my nephew who works for the feds. Is there a trick to drill these on center? I try using my centering jig, but it isn't working for me.

 

[Craftdiggity]

Hi, Jim. I had that problem with my first casing. What I do now is wrap some 150 grit sandpaper around a small screwdriver and scratch out the tube really good. Sometimes there is some epoxy in there or the tube may have a slight imperfection, etc.

With the 30-06 shells you will need to push the twist mechanism in pretty deep. make sure you go slowly and test often as you go. Be sure that the mechanism still twists as you push it in.

As for drilling centered, I use a chuck in the tailstock of my lathe and a set of pin jaws on my chuck for a perfectly centered hole every time. I have never drilled a centered hole all the way through using my drill press. I finally got sick of it and got the lathe set up.

Chris

Chris

 

[Mac]

I have a couple of ? s
Are the brass that you buy soldered in or glued in?
What kind of press are you using to press the tranny in?
Is your centering jig centered on your press ?
Have you the stuff to drill on the lathe? such as jacobs chuck, and four jaw chuck with pen jaws or can you make donut with a slit in it to mount in a chuck to tighten up the brass?

 

[maxman400]

I have Done quite a few of these and the reason that you are crushing the tranny is the tube expands when you press in the the transmission, the base of the cartridge is re-enforced (thicker) to allow the primer to be pressed in. The thicker brass 1/4inch will not allow the tube to expand resulting in you crushing the tranny. I have a drill bit that I use to ream out just about a 1/4 of an inch (of the tube) which allows the tranny to just get by the thicker brass of the cartridge then the tube expands normally.

Drilling: The only tip I have there is to remove the primmer which then leaves a hole that is dead center of the shell and this helps guide your drill bit and keep it on center kind of like a pilot hole. I have done this on my wood lathe, metal lathe and drill press.

 

[cozee]

As previously stated, the brass tube expands when the transmission, or any other piece of hardware is inserted into place. If the tubes are soldered in then there is no room for the tube to expand so the pressure is transferred to the next weakest point, to the upper portion of the transmission. Since I solder them I use a reamer, .247 if I recall correctly (I'd have to go look at it to be sure). I have a drill stop on the reamer set to the depth the transmission needs to be inserted to help reduce time and questions.

I knock out spent primers (ONLY FIRED ONES) with a punch and the casing setting in a holder I made for this purpose. As also mentioned, using the casing pocket to help center you bit is spot on.

 

[traderdon55]

As others have said the brass cartridge leaves no room for expansion. I have started drilling into the tube with a 1/4 inch drill bit. This shaves just enough of the tube to allow the transmission to go in without crushing. I have not crushed a transmission since I started doing this.

 

[Sylvanite]

Under normal conditions, the brass tube expands slightly when you press in the transmission. When glued or soldered into a brass shellcase, however, the tube has no place to go. The solid portion of the case head (called the web) is too rigid.

On a 30-06 shellcase, the web is only about 1/4" deep, and the transmission typically seats farther in than that. Therefore, if you ream out the tube with a 1/4" drill bit, 1/4" deep, the transmission will slip more easily past the restriction and press fit where the tube is uncontstrained.

I ream my cartridges with a letter "F" bit, which is actually a little bigger in diameter than 1/4". The transmission then drops freely through the case web.

The trick to drilling a concentric hole is to drill on the lathe.

Regards,
Eric