550 Gibbs

[krish]

 

[teklanika_ray]

I have 505 gibbs, and 550 magnum in wetherby brass. Do have actions that i can build 550 gibbs.
Krish

I think I'm going ahead with the 550 Gibbs. I have not talked to the guy in the video yet, but that recoil looks manageable.

I don't know that I am necessarily after the whole 505 family, as Flewis suggests. At least I had never consciously thought about it, but I appear to be headed that way. It has been an educational experience.

 

[Flewis]

Lol, now why would you do that sir?

Just trying to help!

 

[teklanika_ray]

Just trying to help!

I did take a look at it. I think I'll hold my course with the builds I have going.

 

[teklanika_ray]

i went with a 40deg. shoulder (between the gibbs and rigby) and a slightly tapered case (about the same shoulder height as the gibbs). Case capacity was 201gn H2O. when fitted to a-square gibbs data, with a 700 gn Hawk, gives 2150fps with 24" barrel at Maximum Gibbs CIP pressure. Case wall is thinning on the low side.
Mr. Ray, if you could measure the case wall of your firefomed gibbs to 550, would be helpful going forward.
Steve

View attachment 649394

505 Gibbs .0160
550 gibbs .0125
I can't read this damned Tube Micrometer I bought to take these measurements yet, but here are the pictures.

 

[Jefferry404]

The 550 reads 0.011
The 505 reads 0.012
but the brass needs to thin more than this.
Is the Gibbs Jamison brass? as the neck seems think.
Tube micrometer is the proper tool.

 

[teklanika_ray]

Crap, I used two different pieces of brass.
The 505 Gibbs is Jamison Brass, the 550 Gibbs is HDS brass. When I get home I will find like brass and remeasure. Do you want measurements from both brands?

I got the reamer prints and converted them to PDF if you are interested in them send me an email at:
alaskan.tinman@gmail.com

 

[Jefferry404]

Crap, I used two different pieces of brass.
The 505 Gibbs is Jamison Brass, the 550 Gibbs is HDS brass. When I get home I will find like brass and remeasure. Do you want measurements from both brands?

I got the reamer prints and converted them to PDF if you are interested in them send me an email at:
alaskan.tinman@gmail

Ray,
I asked for the case measurements of the 505 brass before and after you sized to 550 per your post below:
"
Well, I blew out a 505 Gibbs and seated a .550 700 gr Hawk bullets in it. It doesn't leave much shoulder, but it looks usable
"
so we all could see how much the neck thins when expanding this much.
Steve

 

[teklanika_ray]

Ray,
I asked for the case measurements of the 505 brass before and after you sized to 550 per your post below:
"
Well, I blew out a 505 Gibbs and seated a .550 700 gr Hawk bullets in it. It doesn't leave much shoulder, but it looks usable
"
so we all could see how much the neck thins when expanding this much.
Steve

In the interest of being thorough. Here are four different manufacturers before and after expansion.