Modern & Vintager Pressure Diff?

[sage1]

If low pressure shells are below 8,000 lup (6K to 8K) what are modern day pressures up to in a typical 2 3/4" 16ga 1 oz shell? Thanks S1

[Researcher]

The SAAMI spec for 16-gauge shells is 11,500 maximum average pressure in PSI. In that the big companies seem very reluctant to say anything about the pressures of their ammo other than that it is within SAAMI specs, one needs to back into this info. The 15th edition of the Winchester Reloading Guide shows that a Winchester/Western compression formed hull with a Win 209 primer, 20.0 grains of WSF, WAA-16 wad and 1 ounce of shot, produces a velocity of 1165 fps at a pressure 8,400 psi. This loas has the * next to it that means "This load will duplicate the ballistics of the factory Winchester 2 1/2 dram eq. Promotional Field Loads." Up the powder charged to 21.0 grains of WSF and velocity is up to 1220 and pressure 9000 psi. The heaviest 1 1/8 ounce 16-gauge reload they list is at 10,900 psi.

[Twice Barrel]

If low pressure shells are below 8,000 lup (6K to 8K) what are modern day pressures up to in a typical 2 3/4" 16ga 1 oz shell? Thanks S1

The 16 gauge reloaders group has been testing factory 16 gauge loadings for a number of years and loads are generally in the 8,500 to 10,500 psi range, however, several have been tested that fall below that range and a number, primarily, 1 1/8th ounce loads exceed that range. One load by a foreign manufacturer even exceeded SAAMI standards.

The reason that manufacturers are reluctant to publish chamber pressure data is that they are loading to a set muzzle velocity and constantly changing powder and charge weights to maintain those velocities based on availability of suitable powders and costs which leads to variances in chamber pressure from lot to lot. Small companies such as RST more closely control their components and load to a set standard of chamber pressure and velocity and are more often likely to publish or release chamber pressure and muzzle velocity information.