[Hardcsh]

In the Hodgdon reloading manual it list the following loads for 20 ga. Remington STS plastic hulls that is confusing to me.
1. 7/8 oz. Lt., 15.2 gr of Universal powder/ 9,100 PSI, Rem 209P primer, RXP-20 wad, 1100 fps.

2. 7/8 oz., 14.0 gr of Universal pwdr/10,700 PSI,Rem 209P primer, RXP-20 wad,
1200 FPS.

First what is the difference between 7/8 oz. Lt. and 7/8 oz. ?
Lastly, why does more powder produce less PSI and 100 less FPS ?

 

[mike campbell]

I think you got the 14.0 grains load from the INTERNATIONAL Clays data set. It's a faster burning powder, thus a lighter charge with higher pressures....all very typical.

If you go to the website data, it maks perfect sense. There is no 14.0 grains, 10700psi,1200 fps load listed in the either UniClays data set. The lightest charge shown is 14.5 grains.

With your components, the 7/8 Lt. data is 15.2 grains, 9100 psi, 1100 fps on the low end.

And the 7/8 is,

16.7 grains, 10700 psi, 1225 fps on the high end

Apparently, the Lt. data means "light", as in 1100-1150 fps, whereas the regular 7/8 data is 1200-1250 fps.



That help?