Load for .510" Skidmark Express

[Topshot]

I have gone over to the dark side and am building a big bore long range hunting hammer.
I found the easiest way to do this was to put a 30 inch long .50 cal barrel on my .375 Cheytac and run a wildcat based on the .505 Gibbs parent case.

Bullet of choice in the .510" Hornady A-Max 750gn projectile.

Now comes the interesting part. What powder and load do I use? I have been unable to track down any loading data for a round like this.

Anyone have any experience with similar rounds or access to Quickload that would like to help me out with a starting load?

Thanks.

 

[Topshot]

Anyone?

 

[old_heli_logger]

I don't know anything about it, but I sure like the name hahahaa!
Do you have any idea what the case capacity might be?

 

[Topshot]

Yeah, it may leave Skidmarks in my jocks when I fire it.....

I measured the case full of water and it held 179gn.

OAL of the loaded round when throated right is 5.100"
The A-Max is 2.545" long

 

[J E Custom]

I looked at this type of build a while back, And I also liked the 505 Gibbs case. but the availability of cases and other accessories looked like it could limit the usefulness of a wildcat based on the 505, so I decided to go with the 50 BMG to start with and then do an improved version using the BMG cases because of volume and availability of the case.

Brass is a lot cheaper and very available .

"BUT" then all of the ranges in my area band using the big 50 and most cases over 338 so I abandoned the 50 project.

Kirby Allen (Fifty Driver) did some work on the 50's and would know a lot more about them and also uses the 505 case for some of his rifles, so maybe he will chime in.

J E CUSTOM

 

[MagnumManiac]

I have gone over to the dark side and am building a big bore long range hunting hammer.
I found the easiest way to do this was to put a 30 inch long .50 cal barrel on my .375 Cheytac and run a wildcat based on the .505 Gibbs parent case.

Bullet of choice in the .510" Hornady A-Max 750gn projectile.

Now comes the interesting part. What powder and load do I use? I have been unable to track down any loading data for a round like this.

Anyone have any experience with similar rounds or access to Quickload that would like to help me out with a starting load?

Thanks.

I have and shoot the 505 Gibbs in a custom CZ550, I run 600gr pills in mine with H4350 (soft loads only) RE22 and RE25. I was advised not to load under about 130gr, as it runs into ignition problems and requires fillers. 2 other powders, amongst many, also come to mind but I haven't tested them yet, are H1000 and Retumbo. I feel these will run a little better on the fill capacity and should give uniform burns with good velocities.
I run loads with RE22 at 140gr and RE25 at 145gr, either load can be increased but I find 2350fps to be my limit on an unbraked rifle, although my rifle does have a mercury recoil reducer.
You could start around 130gr with RE22 or 135gr with RE25.

Cheers.
gun)

 

[Topshot]

Thanks MagnumM
My rifle will be about 25ln and braked so would be a bit nicer to shoot with the 750gn pills.
I may give the lighter ones a try also.