Cheddite Primer pressure spikes

[Gary Laudermilch]

After reading this thread and others on different forums relating to pressure increases with Cheddite primers it has raised some concerns. There are plenty of anecdotal comments that suggest Cheddites and Win primers are interchangeable. Data presented seems to indicate otherwise. So I decided it was time to do some testing.

My to to powder for 20 ga has been WSF for decades. I have shot in excess of 50,000 of the load published on the Hodgedon site in all kinds of weather and patterned them extensively. The only substitution I made was using a Claybuster 1078-20 wad for the Win wad.

So, I sent my standard load of 16,8 gr. of WSF off to Precision Reloading and just for the heck of it included a load at 16.3 gr of WSF. Both loads substituted a Cheddite primer for the Win.

The Hodgedon site lists 17,0 gr for 1200 fps at 10,500 psi.

The results are attached.

Addtionally, my son had 600 shells loaded with 20/28 and Cheddite primers so we sent them as well. Alliant lists his load of 15.5 gr at 1200 fps and 1010 psi with the CB wad.

All loads were scale weighed to be exact. In retrospect I wish I had included shells with the Win primer as a baseline and to confirm the published data.

Draw your own conclusions.

[Randy Roberts]

Originally Posted by Gary Laudermilch

In retrospect I wish I had included shells with the Win primer as a baseline and to confirm the published data.

Gary that's a little concerning for sure. In an attempt to prod you into doing so I am in total agreement with your statement on sending your Win primer load in for testing. That would be the tell all in my mind for comparison purposes. If that load has never been tested this info you have just disclosed would make me a little timid about shooting them. Could there really be that much of a spike in this primer switch ? Test the Win load and find out, please ..... Thanks !!

[Woodcock survey]

Gary, that is very concerning. I do not load to max. on anything but use that 20/28 load with a grain less and never thought it would be near that. Yes ,wish the Win. primer had been included.
We will have to be careful in that Cheddite seems to be the only primer available.
Thank you for doing this.

[MattHaney]

This thread got me thinking about the various Cheddite primers and published loads. I asked Hodgdon what primer their loading data assumes:

For loads that use Cheddite primers (Ched 209), is any particular Cheddite primer assumed? Cheddite currently offers 3 primers, CX2000, 1000 and 50. Does it matter which one is used for the published loads? Thank you!---Matt

Matt Haney

Help Account <hpchelp@hodgdon.com>
Mon, May 2, 10:20 AM (4 days ago)
to me

Cx 2000 is the one used for the data and the most commonly available for reloaders.

[Mike of the Mountain]

If you look at reloading specs such as in the BP Advantages manual, the listed loads for Cheddite primers only say Cheddite 209. There is no reference to CX2000, 1000 or 50 due to the reason Hodgdon states regarding accessibility. With those pesky lawyers involved with everything, you'd think if Cheddite 1000 or 50 were used for the data that it would be included in the recipes.

[Mike of the Mountain]

Gary, those are some snotty loads! Personally, whether hunting or shooting clays I'd keep my velocities at 1220 max with 7/8 oz payload.

[Gary Laudermilch]

I have no desire to load and shoot a load in excess of 1200 fps preferring something under. Because I trusted published data I never saw a need to test. That assumption may or may not be correct. In fact we do not know this test data reflects what goes on in a typical barrel. To that, note the bore diameter of the test barrel of .614, That is a bit tighter than a typical 20, at least the one's I own which are closer to .618. Not much difference but how much does it take to uptick pressures?

I do plan on submitting additional losds for testing and included will be my base load with a Win primer.

[Steiner]

Would lengthening the forcing cones be an effective way to reduce pressure and act as a bit of a saftey net?

[Art Kirkwood]

Originally Posted by Gary Laudermilch

I have no desire to load and shoot a load in excess of 1200 fps preferring something under. Because I trusted published data I never saw a need to test. That assumption may or may not be correct. In fact we do not know this test data reflects what goes on in a typical barrel. To that, note the bore diameter of the test barrel of .614, That is a bit tighter than a typical 20, at least the one's I own which are closer to .618. Not much difference but how much does it take to uptick pressures?

I do plan on submitting additional losds for testing and included will be my base load with a Win primer.

Gary, My Briley 20 ga tubes are 0.618 also and I agree that the test barrel 0.614 seems tight. The volumetric difference between the two bores is only about 1.3% which doesn't seem significant. What I wonder is how did Hodgdon measure the pressures of therir published reloads? How does their pressure test equpiment differ from what Precision is using to measure pressures? Your tests of identical WSF 20g loads except one used CX2000 and the other used W209 primers showed that there was about 440 psi difference in average pressure with the CX2000 being the hotter primer. The big question for me is how are the powder suppliers measuring pressures of their published recipes and how does it differ from how Precision does it?

[Dean Romig]

No, not appreciably...





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