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What's the tolerance between an ammo casing and a chamber?
- Thread starter Pcmaker
- Start date
You can find the cartridge and chamber specifications here
saami.org
New & Revised Cartridge & Chamber Drawings - SAAMI
Cartridge and Chamber Designs Standardized by SAAMI Note: Current Cartridge & Chamber Drawing documents are contained within the SAAMI Standards. They can be found HERE. Newly Accepted Cartridge and Chamber Designs Links to technical data and drawings for the newly SAAMI accepted Cartridge and...
saami.org
- Joined
- Nov 17, 2017
- Messages
- 1,525
In a standard SAAMI bottle necked rifle cartridge, you will want about 0.003" between the bolt face and the shoulder on the case--that is the shoulder allows the cartridge to move 0.003" back and forth longitudinally.
Radially, bolt guns can operate with as little as 0.000" diametrical clearance (but NOT negative clearance!), autoloaders need at least 0.001" diametrical clearances. There is a little test we run called the "plop test" you put a sized case into your hand and place the neck in the chamber and let go, the case should fall into the chamber and when the shoulder reached the chamber shoulder it will make a sound that sounds like "plop".
And then there is the jump-distance--the distance between the ogive of the bullet and the lands of the rifle barrel. My better guns tend to like 0.015" jump distance, although some of the not as accurate ones are less picky.
Radially, bolt guns can operate with as little as 0.000" diametrical clearance (but NOT negative clearance!), autoloaders need at least 0.001" diametrical clearances. There is a little test we run called the "plop test" you put a sized case into your hand and place the neck in the chamber and let go, the case should fall into the chamber and when the shoulder reached the chamber shoulder it will make a sound that sounds like "plop".
And then there is the jump-distance--the distance between the ogive of the bullet and the lands of the rifle barrel. My better guns tend to like 0.015" jump distance, although some of the not as accurate ones are less picky.