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Joined: 09 Sep 2006 Posts: 863 Location: NoDak

Hi all, say, I have a recipe that call for 1 /16th oz payload, but would like to increase the payload to an even 1 1/8oz. would this increase the pressure? If so, by how much?

The load is:

16ga
2 3/4" Cheddite Hull, fold crimp (may use a OS Card for better crimps)
Cheddite Primer
22grns of PB Powder
Z16 Wad

The published data with 1 1/16oz payload is: 1265fps and 10400psi

Your thoughts please.

Thanks as always!

Greg

I'm certain that pressure is non linear and the only way to tell is to have the load pressure tested. Be safe.

I'm certain that pressure is non linear and the only way to tell is to have the load pressure tested. Be safe.

does NOT look like a good Idea. there are lots of tested 1 1/8 oz loads out there dont be fooling around with increases in shotshells. If you have to ask this question then you need to use published data. I have only nine fingers because of a barrel rupture. It is just not worth it

Joined: 09 Sep 2006 Posts: 863 Location: NoDak

Hi, okay, so let me ask this, the increase of just 10 pellets will push the published psi of 10400 over the SAAMI max of 11500psi?

Not being a smart a$$ here, just trying to get a handle on this.

Thanks!

Greg

depends on what pellets - 9's might be ok ... 4's - well you already know that answer ! what the boys are trying to say is that it's a crapshoot . DC would probably know the most exact answer - me , I'd check the data for that load in 11/8 . Would leave it alone if not there .

The answer is.......we are all just guessing......adding weight to the shot load is the quickest method of building pressure.

A #4 pellet weighs approx. 3.12 grains x 10 pellets is 31.2 grains. According to reasonable reloading practices, you should never vary the payload weight more than +/- 20 grains from the data.

Adding 10 #4 pellets is 50% over that guideline.

Think about this, adding 1/8 oz (about 55 grains) of pellets to a load can account for an increase of pressure of 1000 PSI and higher with slower burning powders than PB and the correct wad. You have the wrong wad and PB......which direction do you think the pressure is going to go?

Are you going to rupture a barrel? Probably not. Is this a smart thing to do? Probably not.

Two things you also need to think about......the Z16 wad is not the wad for 1 1/8 oz loads.....PB has either been discontinued or will be in the near future.

Adding 1/16th oz will increase pressure. the trickey part is that there is no way to calculate how much. Going higher than the suggested MAX pressure does not mean that the barrel will burst. The pressure suggested as the maximum is an industry standard only. If the ammo you make stays bellow that standard then you will be fine, Unless the gun or barrel is physically defective or there is an obstruction in the tube.
One fact that many new loaders misunderstand is that Pressure and Velocity are not related. If the gun kicks to hard it is because the load is to heavy or to fast or both.

Joined: 09 Sep 2006 Posts: 863 Location: NoDak

Thanks again all!, okay, just tossing this out. If I decreased the powder charge from 22 grns to 20 grns, that would put me at 9454psi instead of 10400pis.

So do you think that with this decrease in powder it would offset any increase from the payload increase?

Just a thought.

Thanks!

Greg

Since this data obviously came from BPI, call them.

There is no way to know unless you have a pressure gun that will use a Piezo sensor in it to read the pressure. Then it is only accurate for the one fired load. The pressures in the data are averages of 5 to 10 tests depending on the standard deviation and if that deviation ,when added to the highest test number is bellow the standard for MAX then it is considered to be a safe load.
Reducing loads in either powder or shot is ok but you dont know what your shooting and it may not fill the hull correctly, which also affects pressure.
Guessing at this stuff really dosent work

Member Joined: 02 Sep 2010 Posts: 829 Location: SW Ohio

I would just leave it at 1 1/16. Do you really think that extra 1/16of an ounce of shot will significantly improve the pattern? I would spend my time patterning it to get the best choke option. Extra shot may just give you more fliers or blow the pattern.