Hey Fellas,

I was reading the thread on big bore case comparisons the other day and I decided for reliablility, component availability, case quality,...etc. something new is needed. (at least for me )Some really interesting things came out of that thread.

I'm calling this new heavy the .500 Dark Continent or .500DC for short. It is based on the .505 Gibbs case for which there are alternative sources to Bertram (some say too soft), unlike the .500 Jeffery.

The specs are:

Neck dia.-.540
Shoulder dia.-.600
length to shoulder-2.300
overall length-2.850
shoulder angle-25 degrees
Rim thickness-.060
If someone would please help me out with the neck length. I want the case to be 2.850 and the soulder angle to be 25 degrees. How long would the neck be? I think around .420-.460. The body taper is between the Jeffery and the Gibbs. The case has a .030 shoulder and at 25 degrees should extend case life a little. The case head will not be rebated like the Jeffery but left full diameter. Of course the bullet dia. is .510.

I'd like to order a reamer pretty soon and chamber a ruger #1 in this number. After load development I will build a full dress British express on a CZ 550. Can someone please help on the neck length?

Thanks to all for making this site great,

-Catter

Wildcatter,

If my calculations are correct, a 25 degree shoulder would leave a neck length between .485" and .486".

Hope this helps,
Cannon

Wildcatter,
Sounds great!

I would back that shoulder down some more to give a neck length of one full caliber of bullet: 0.510" neck length.

This would actually broaden the shoulder a little bit or allow you to taper the case a wee bit more and keep the same shoulder width.

You are still going to have more than enough case capacity with the longer neck, and have a little better grip on the bullets in the magazine under recoil, etc...IMHO.

------------------
RAB

I agree with Barry, or you could just order a 505 Gibbs Improved reamer, thats about where you are right now if I read it correctly....I built one of those a few years ago and I still have one of the cases.

------------------
Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

Thank you so much,

That neck is .485. I thought it would be pretty close to one full caliber in length. I will back the shoulder up a little to get one full caliber. By the way, does anyone know how 470 Mbogo got his headstamp on his brass. I'd like to obtain some 505's with my own headstamp on them.

-Catter

[This message has been edited by Wildcatter (edited 10-30-2001).]

[QUOTE]Originally posted by Wildcatter:
Hi Wildcatter,
I got my bunter through Jay Bell at Mast Technologies and the rest of my press was home made. You can see the pictures of the mandrill and the press that I made. You should start off by cutting a section out of a brass and having a mandrill made that fits the inside shape of your brass perfectly. With this mandrill complete I had it threaded to fit a standard 4 ton car jack. The 4 ton jack will stamp the brass properly and not blow seals. Make sure the material that you make the mandrill from is very hard. I started with a grade 12 bolt. You can build a heavy frame to mount the jack in but really make sure you keep everything in line. I took a piece of round stock and had it bored and squared of inside to mount the bunter into. This is the round piece you can see welded on the underside of the top rail of the press. This is locked in place with an allen screw so the bunter could be changed in the future to lets say a necked down 470 Mbogo to lets say 35 caliber called the 358 African Plains Game or 358 APG for short. Best of luck with your project. My website for the picture of the press and mandrill is www.470mbogo.com.
470 Mbogo