7x57 M77 pound cast

[Dick West]

Following Ian's instructions here, I made my first attempts at a pound cast. For the slug, I drilled a hole in a 2x4 and poured in soft lead. (It was a pain getting it out.)

I'm not quite sure how to read it. I haven't done any measurements yet.

I'm really curious to do a pound cast of my wife's Spanish Mauser sporter.

Both photos are the same slug, sorry bout the focus.

 

[Brad]

I would measure the diameter right above that ring that looks to be about .100 above the end of the neck. Size bullets right at or just a hair under that diameter. By a hair I mean 1/2 thou under that size.
Plenty of freeborn there. You need to seat bullets out so the bullet almost kisses the throat, maybe .050 short.
Of course alloy, pressure curve from powder selection, and desired velocity all come into play.

If you look around the cast do the lands all appear to start at the same point? Do the lands appear the same in taper at the end?

 

[Ian]

Read part two of my article, and then scroll down the page and read the most excellent synopsis of the whole impact impression/pound cast/throat slug process as written by Outpost75. After reading through his more condensed yet comprehensive post you should be able to understand what you're trying to accomplish with the cast, why you're doing it, and what to measure.

 

[JWFilips]

Love to see a clearer photo: Looks like you camera focused on the background fabric. Maybe try again but not so closeup May make it focus sharper on the slug

 

[fiver]

I can make out the ball seat area and then the free-bore before the rifling.
I would measure the slug and make a drawing.
and include a traced outline on the paper.
make your measurements from the base of the case so you have a reference point.
it would look something like this.
l----------l
l----------l-l
l----------l---l

with a base length starting at the mouth of the case for reference..
then use the l--l for + distance, and diameter.
even if you use jacketed bullets you want the distance to lands just so you can measure your ogival jump.

 

[Dick West]

OK, I took some sharper photos and marked the rifling with a Sharpie to make it stand out. I took 2 photos of the Ruger cast to show get all the detail.

I also did a pound cast of my Spanish 1891 5x57 Sporter. Unfortunately, my home-made slug didn't seem long enough to reach the rifling. I'll try again when i've got time.

Note: I'm math challenged and am self-taught in the use of a micrometer.

Ruger M77 (tang safety) pound cast:
The groove seems to be 0.284. The flat area (throat?) seems also to be 0.284. The ungroved area just behind it is about 0.285 and the band of lead is 0.293 and the case mouth is ever so slightly bigger (0.2925-0.293).

Spanish Mauser sporter pound cast:
Note: I need to do another pound cast with a longer slug because I didn't pick up any rifling at all.

The very end of the cast is 0.286 the it gradually tampers up to 0.292-0.293 right before the band of lead in front of the brass mouth.
like I said i need to make a longer slug and do another pound cast.

Fiver: here's my measurements for the Ruger: (note: is is a '06 case resized to 7x57)

|--case length---2.23"--------------|

|--case length---2.23"--------------|---| 0.09" lead band

|---------------------------------------|---|-0.20"-| smooth area before rifling

Spanish Mauser:

|-----------case length 2.23"-------|

|---------------------------------------|-X--| "X"=0.10" lead band

|---------------------------------------|----|---0.36------> smooth area (chamber and throat? tapering from 0.293" at case mouth to 0.286" where it ends with no sign of rifling.

 

[fiver]

your gonna fill that band of lead in front of the case with more lead when you re-slug the Spanish mauser.
a 289 or so measurement won't be a surprise to me, many of them get up to .290.

this should look familiar.

 

[RBHarter]

Bought a donor rifle once in a 7mm wildcat sort of a AI . It was eroded out to .300 .......