Over shot card
 

Will A over shot card change the barrel pressure?

All other things being equal, I would think the pressures would be minimally higher due to the increased mass of the card

According to Precision, my roll crimped paper shells, with overshot card, were consistently lower than my same charged, folded crimp shells.
An overshot card, used as a filler, atop the shot, then fold crimped, may be infinitesimally higher than without the card. ( A bag of 500 over-shot cards might weigh a few ounces.)

over shot card
 

If you're really concerned, do as I do. Subtract an amount of shot equal to the weight of the card wad and you're good to go.

Use it. You will never know the difference pressure wise.

take out one piece of shot and you will likely balance it

but - why are you adding the card? poor crimp?

i use these over buffered loads to keep the fine powder from leaking out which sometimes happens even with a good crimp ( i have opened flats of factory buffered shells and found some buffer powder has come out)

https://www.precisionreloading.com/c...#!l=PRP&i=TS12

they are so thin I find I often have two or even three picked out together - and they are very flexible so there should be no affect on the pattern

Over shot card
 

I use different thicknesses of wads, mostly .125 (sometimes more than one) to help get a perfect crimp.

Over shot card
 

Of course I always place the wads in the bottom of the shot cup before I add the shot. Duhhh:

Buddy,

Many of us that reload 10 gauge with 1 1/8 or even 1 1/4 oz of shot place various shot cards in the bottom on an SP 10 plastic wad to accomplish the same thing you are. I'm shooting these 10 gauge shells in an 1881 Lifter Parker with Twist Steel barrels with impunity (so far). I would not worry about it.

Harry

I’m having a hard time believing Buddy was serious. One overshot card weighs about the same as two or three #8 pellets. Most presses drop far more pellets deviation. Run 10 drops. Weigh them. The deviation will make an overshot card seem light compared to the tiniest fart.