8x72r

[Diz]

toadboy,

Here is a rather crude drawing of the 8 x 72R that I copied from one of my references. Anyone having something different please correct me. Hope this helps.

Thanks, Diz

8x72R scan.jpg

[toadboy65]

Well, I tried something. I don't know if it is clever or stupid, between which there is always a fine line. I heard some mention of swaging bullets. I don't know what sort of gear you use for that, so I took a piece of 1" steel plate, and put a tapered hole in it, starting at .323" and coming out the other end at .316". I pressed some of the greased .323" bullets through it, and they came out .318". I rammed them through with a .318" rod, and it left a ridge on the bottom of the bullet. So the bullets are not terribly attractive. I suppose I need to file the ridge down for balance, although the bullets will be lighter. However, I ought to be able to load these and figure out which combination of dies I need to use to get the cases tight around the projectiles, and achieve the proper taper on the cases.

[Diz]

toadboy,

I posted some pictures of tools I made for resizing bullets and you can check them out. Comments from some of the very knowledgeable members are worth the reading. Check out the following:

Gehmann-Konstanz 5.6x61 vom Hofe posted 2-22-2015

Bullets for 9.3x72R drilling posted 11-05-2015

Another type of die posted 12-08-2015

A bit of advice may be to take your bullets down in two steps instead of one and make the process a little more gentle. Also something I just learned and was confirmed by Sharps is to push the bullet through BASE first since it is the base that "steers" the bullet you want it in perfect shape. I have a picture of the difference here somewhere and will have to look it up.

Thanks, Diz

[Diz]

toadboy,

I found the picture of the bullets. They are Lyman 360 grain .515" diameter swaged down to .497 for my cape rifle. That's eighteen thousandths and moves a lot of lead around. The bullet on the left was pushed in nose first and shows a lot of rough metal around the base. The right hand bullet was pushed in base first and shows a smooth bevel on the heel (except for the marks where I dropped it).


Bullet Swaging.jpg

I just had a chance to shoot the ones that were sized base first and with no other changes it looks like the group has improved by about an inch. Also, the bullets in the picture were not lubed before sizing but the bullets I shot were and this hold the lube grooves open for less distortion. For what ever help it's worth.

Thanks, Diz

[mike ford]

toadboy65,
It looks like you are taking the right approach to your project. Once you get a cartridge fired in your rifle, you can see if it will take a .319 bullet. If so you can just polish your existing die out to give the dia, bullets you need. Did you ever get a case to chamber? If you get the body to chamber easily, you may find the rim needs some modification. If so, the needed mods. should be selfevident. If you still can't get a case to chamber, I know a couple other tricks, but only as a "last ditch" effort.
Mike

[toadboy65]

Well, I fired a 8 x 72R round. The brass I had was fairly close, but I had to use a crimping die for .300 Blackout. I also ended up putting the brass on a small lathe to cut a tiny bit off of a few places. But one round finally fits in the gun. I loaded it with 37g of the powder that I can't remember, and a 200g .318 copper jacketed bullet. It fired fine, and I reloaded that case again. tomorrow, I will get the chronometer out, and see what I have to do to get an optimum load. Thanks to everyone for the help.

[mike ford]

toadboy65,
The fact that you used a lathe to modify the cases is both encouraging and concerning. It is encouraging because it opens a whole new world to you, such as sizing dies to fit available bullets to your barrel, like you tried above. In my opinion a lathe is a requirement of life. The concern is any changes in the body dia, should come through sizing and fireforming. Turning on the lathe should be limited to the rim and "solid" or thickened part of the head. BTY, I have found that a square corner on the under side of a rim, together with a radius in the rimrecess makes a proper thickness rim seem too thick.
Mike

[toadboy65]

One of the things I did was round the rim a little bit. I also took about 2/1000ths of an inch off of the body of the case, in the 2mm nearest the rim. I do not plan to do this with all of the rounds, but I wanted to make one round that perfectly fits the chamber, so I can use it as a reference. Since I judged that I had not taken enough material off to significantly weaken the cartridge, I decided to fire it. My thinking was that It would confirm the correct bullet size, and also that the case would expand in the chamber if I had brought the profile down too much. The reloaded cartridge still fits the chamber nicely. Of course it is hard to tell if the shells I got are the problem, or if they were supposed to be "close but not quite right". Even though I did a nice chamber cast, and took the measurements when I was supposed to, we are dealing with pretty tight tolerances. I kind of worry that even if I get the custom dies, I am still going to end up with cases that almost fit.
Of course what will probably happen is that I will go to an incredible amount of trouble to start manufacturing these cartridges, then to justify the expense I will talk myself into buying six more rifles in this caliber. that seems to be the way I do things. One time I bought an interesting bayonet for a couple of dollars at an auction. So then I had to track down a rifle to go with it. Then I discovered that the original bayonet had been modified, and did not match my pristine original rifle. So I replaced the bayonet with a better example. And of course I had to get the right original sling and started reloading the ammo. Of course now I have four examples of the rifle, with matching bayonets and everything else that goes with them. And I only got the drilling because it was part of a set that was commissioned by a famous person, and I wanted the other rifle. They wanted to sell them together because the drilling was horribly damaged.

[mike ford]

toadboy65,
You sound like a "man after my own heart." If you only took 0.0002" off the body, I can't see that you hurt it anything( that's only 0.0001" to the side).Where you made the cut is the solid web area of the case. If you can get enough cases fireformed, you won't need custom dies. The fireforming fits the cases to the chamber and common dies can be used to neck size and seat bullets.
Mike

[Axel E]

The problems with forming tapered cases like the 8x72R, 7x72R, 6.5x58R S&S or 8x58R S&S from 9.3x72R brass, using standard American (RCBS) full length sizers are well known in Germany. As you noted, due to the shell holder prventing the last few millimeters of the case from entering the die and the springyness of the tapered cases, case forming is often insufficient near the base. Two remedies are in common use over here:
1.) Grind of about 1 mm = .05" off the die bottom to allow the die to be screwed in deeper. Sometimes this is sufficient.
2.) Remove the decapping/expander assembly from the fl die. Use a small, f.i. .22 Hornet, shell holder to push the case all the way, up to the rim, into the die. Use a rod and hammer to push the case out of the die. After you have done this once, you can reload the fireformrd cases in the usual way.

[mike ford]

Toadboy,
Axel's advice is very good, but since you have a lathe, there is another way to shorten the die. I shorten them from time to time, with a sharp carbide tool in a lathe. I turn the sizing die into a 7/8-14 split threading die (not a solid re-threading die) and then chuck the threading die in the lathe, using the tailstock center to center the sizing die. It will then "run true" and you can cut from the center out. It will "squall" at first, but this will settle down once you get through the hardened exterior .
Mike

[toadboy65]

I will try. I got a little sidetracked on other projects, but I will be back at this project in a couple of days. I am not sure how many rounds I really need. I don't expect to shoot this one very much, unless I can get the scope mount issue dealt with. I will probably carry the drilling for bird hunting in the fall, with a rifle round in the chamber, just in case. I have a bunch of good rifles for long distance shooting, so I can't see hunting elk with the drilling.