Chamber Casting

K

Kevan

CGN Ultra frequent flyer
EE Expired
Rating - 100%
24   0   0
Location
Lower Mainland B.C.
I think that I have a rifle with a wonky chamber ( egg shaped ? ) and I'm looking for info to do it myself.
Handloads fired using virgin brass make very tight groups while same fired using once-fired from the same chamber are all over the place and bullets feel different when seating.
All resized cases are trimmed and chamfered but I do not have a mike to check the roundness of the cases.
With that in mind any tips on chamber casting will be most appreciated, also a location in Canada where I could buy Cerrosafe ... not Brownells..
 
Roll a virgin loaded round and then a fired case and a reloaded fired case on a piece of glass or very flat counter top... compare the wonkiness...
 
A chamber casting won't do you any good if you don't have something to measure the diameters to check for a wonky chamber. You don't need a micrometer. A set of calipers is just fine for this level of accuracy. And anyone playing with reloading should have a set anyway.

Digital calipers are common but the cheap ones tend to eat batteries very fast. I suggest a set of dial calipers as a nice option. No battery to run down and no nasty vernier scale to deal with.
 
BCRider said:
A chamber casting won't do you any good if you don't have something to measure the diameters to check for a wonky chamber. You don't need a micrometer. A set of calipers is just fine for this level of accuracy. And anyone playing with reloading should have a set anyway.

Digital calipers are common but the cheap ones tend to eat batteries very fast. I suggest a set of dial calipers as a nice option. No battery to run down and no nasty vernier scale to deal with.
Click to expand...

I do do have a couple pair of precise calipers, couldn't reload without them.
One old faithful dial set and a new expensive digital with auto shut-off battery saver.
 
The roll test should give a better indication of what is wrong over measuring a chamber cast.

I have seen warped sizing dies (occurs during heat treatment) that took perfectly straight cases and gave them a slight banana shape. They measured round but when rolled you could see what was wrong. The bullet had extreme run out.
 
An extension of what guntech said; if you full length resize your cases, they should be the same as factory cases for the purposes of accuracy. If there seem to be differences shell to shell, when loading, perhaps you should try annealing the cases before full length resizing. The differences could be from differences in brass stiffness in the neck

cheers mooncoon
 
guntech said:
......I have seen warped sizing dies (occurs during heat treatment) that took perfectly straight cases and gave them a slight banana shape. They measured round but when rolled you could see what was wrong. The bullet had extreme run out.
Click to expand...


Wooooooooooo.... that would/could sure mess up a reloader's head for a while finding THAT one..... And that would be an excellent point for rolling the cases on a known smooth flat surface.

I sort of ran into the same issue of off center bullets in rifle cases. In my case it was a Lee press where the top hole for the dies was not aligned axially with the ram's center line. As the ram was pushed home it made the casing push off more and more to the side as the gap closed. It was actually bending the cases down near the heads ... which I would have seen if I had rolled the cartridges on some glass.
 
You must log in or register to reply here.
Back
Top Bottom