partsproduction
Titanium
- Joined
- Aug 22, 2011
- Location
- Oregon coast
I just bought a Federal air gage without the gage probes. I understand I need a master ring gage for each size needed and the special probes or gages.
A customer who brought an air gage for us to use making his parts paid to have a probe made, I assume I can make my probes following the fashion they are made after.
The button rifling blanks need a .3465" bore I think after experimentation, and fortunately they are ,380 ACP pistol barrel blanks. I was told bores should be ,348" but the rifling is not high enough at that size, however, it might be my measurements too, in error.
Also, I'm told the bore needs to decrease ever so slightly from breech to near the muzzle, though no numbers were given, I suspect tenths are the correct values.
Watching high speed film of shooting I can see the need, as a considerable amount of gas blows out seemingly long before the bullet arrives. Not fatal for a low pressure pistol barrel but likely a cause of gas erosion for high powered rifle barrels.
In my earlier button rifling thread a member mentioned air gaging, and I've come to believe that it is the best way to map the inconsistencies inside the blank before rifling.
I'd be very interested in how gaging is done by commercial barrel rifling.
Thanks,
parts
A customer who brought an air gage for us to use making his parts paid to have a probe made, I assume I can make my probes following the fashion they are made after.
The button rifling blanks need a .3465" bore I think after experimentation, and fortunately they are ,380 ACP pistol barrel blanks. I was told bores should be ,348" but the rifling is not high enough at that size, however, it might be my measurements too, in error.
Also, I'm told the bore needs to decrease ever so slightly from breech to near the muzzle, though no numbers were given, I suspect tenths are the correct values.
Watching high speed film of shooting I can see the need, as a considerable amount of gas blows out seemingly long before the bullet arrives. Not fatal for a low pressure pistol barrel but likely a cause of gas erosion for high powered rifle barrels.
In my earlier button rifling thread a member mentioned air gaging, and I've come to believe that it is the best way to map the inconsistencies inside the blank before rifling.
I'd be very interested in how gaging is done by commercial barrel rifling.
Thanks,
parts