Quarterbore's Forums - 50 EBG ,first shots at the range

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Hello Spook,
I am strugling with my program to calculate the correct twist to stabilise a .50 cal amax at subsonic velocities.

Jope, the forum member from Finland is looking for that info.

Can you help us here?
What twist did you use on your barrel?
Many thanks.
ND

d-mon, When I called JD and asked him about the twist he used for the 510 whisper he told me "About nine".... 14 is pretty typical for 458 cal up to 600 grs so I went 9.25 and havent had problems. I dont suspect it would hurt anything to go a little tighter if theres any doubt as long as subsonic is the intent of the project and the Amax is the only bullet used.

Hello Spook,

Remember that for the 458, most projectiles are simple shape, i.e flat base round nose, .50 cal A-max is a radical Boattail match bullet "a la" Berger.
1in9 sounds good.
Thanks.

ND

I'm interested in building one!

Are the reamer and dies called 50 EBG to order from PTG/Hornady?

Been thinking about trying a Brux barrel as well.

Hi

I´m also interested to build one for myself and my friend wants to do one also.
Do you have any specs about the it?
I plan to use Tikka T3 SuperVarmint as basic gun.

Hekku

Hi, this is my first post and I should say nice job on the low cost 510 Whisper alternative. I was referred here from different site because I am doing something similar. My round is very similar but based on different brass that also is 50 cents each instead of the 4 dollars people pay for the 510 Whisper brass. I will be using either the 50 Beowulf or a shortened 7mm WSM brass casing. Years ago I a had a reamer ground for .50 AE blown out to a straight .540 which allowed seating .510 bullets in BMG barrels with it. The reamer is long enough to do the same thing with the Beowulf round. However I am slightly worried about the highly rebated rim and set back of the web at high pressure so I have also been considering using 7mm WSM brass cut off at the shoulder because it has a stronger case head. The problem with the WSM brass is the web is .555 and needs to sized down to .540 to feed and extract easily.

Below are a few pictures of the rounds I am considering and of an aluminum barrel mock up for the Arisaka so that I could see how the Beowulf rounds feed and fit in the chamber. Since the entire web is inside the chamber I think I will go ahead chamber my 1 in 9 twist Pacnor barrel for the Beowulf round and see how it works.

Jeff

http://i461.photobucket.com/albums/q...andActions.jpg

http://i461.photobucket.com/albums/q.../InArisaka.jpg

http://i461.photobucket.com/albums/q...seinbarrel.jpg

http://i461.photobucket.com/albums/q...ltinbarrel.jpg

So does "EBG" stand for Extra Big Grin?

There's no shoulder and the rim's rebated, so does this cartridge headspace off the case mouth? If so, how's that worked out?

Quote:

Originally Posted by Spook (Post 5416)

jjmcrowell, its a cartridge I came up with... neck up 458 SOCOM to 50 cal. I have a 458 and firing subsonic isnt that impressive, bullet selection leaves a little to be desired as well.
The action is a Savage FV action that I milled the bottom out of to facilitate feeding. The barrel blank was by Brux. I had the reamer ground at PTG and the dies were made for me by Hornady. I chambered it for use without the Savage nut in my shop.

What did the 458 do (or not do) subsonic? I've never done it so I'm just curious what this round would do that a 458 wouldn't. I'm working on my first 300/221 but if all goes well I may be very interested in a larger caliber subsonic.