EPM-18 Primer Formula - Testing and Development

[MUSTANG]

I have been waiting on my Post Flu/Bad JuJu Illness with lingering cough to finally subside. To be productive and avoid boredom; I decided to try mixing a new “Green”, non-corrosive , non-lead primer compound. I went to W. Marshall Thompson’s Homemade Primer Course; Revision Date: June 1, 2021 for reference. He has shared multiple iterations of this paper over the last 10 years or so; the 2021 version can be found at: https://www.aardvarkreloading.com/resources/Homemade%20Primer%20Course%202021-06-01.pdf
I am trying to avoid having to manufacture Tetracene as used in EPM-16, EPM, 17, and others in his manual. Thus; I was intrigued by the EPM-18 formula he listed:
EPM-18 Primer Formula

Bismouth Tri-Oxide 19.5 Gr.
Nitrocellulose (Pistol Powder) 5.0 Gr.
Aluminum (350 Mesh) 3.3 Gr.
Binder 0.3 Gr.
Glass 5.0 Gr.

In his testing; he indicated that he received very weak ignition or Pssssst on firing the Primers.

[MUSTANG]

Knowing that a Phd had poor initial results; but he also that he stated he would look further into it in the future, I bravely (ignorantly?) waded into the pool. My 1st Test consisted of the following mixture. I scaled my initial Primer Mixture production run down to about 9.3 Grains as I do not want to throw out chemicals as I “Find What Does Not Work”.

Bismouth Tri-Oxide 5.52 Gr.
Nitrocellulose (Pistol Powder) 2.1 Gr.
Aluminum (350 Mesh) 1.02 Gr.
Glass 0.7 Gr.

I mixed the Nitrocellulose (Green Dot Powder) and Glass (350 Mesh Ground Glass) together in a ceramic Mortar and Pestal. I ground the two together with the Mortar and Pestal for about 10 minutes to get a fine black colored powder; that was then mixed with the other chemicals until Well Mixed.

I remanufactured 10 Large Rifle Primers using this mixture. The mixture because of the very Lofty/Fluffy 350 Mesh aluminum resulted in more volume than I anticipated; so that excess chemical mix may have to be disposed of since I still have enough left over from this Test mixture for possibly another 15 Primer Fills, and the results were less than desired.

Test Firing Results:
7 Rounds – Slight noise above level of the firing pin hitting the Primer Cup.
2 Rounds – Strong Pssssst sound on firing pin hitting the Primer Cup.
1 Round - Moderate Ignition Bang, very slight flame (1/2 inch?) out muzzle of 24 Inch Barrel.

I will say that I seem to have replicated the results published in the Homemade Primer Course; Revision Date: June 1, 2021. In that reference; it was postulated that the Dark German Aluminum used was not fine enough.

[MUSTANG]

My next Test will go the opposite direction from the discussion in the reference. Instead of trying to find an even finer Mesh Aluminum (it was speculated a finer Mesh was needed to get full Ignition); I am thinking of doing a Test using a 75 Mesh Aluminum Powder I was able to finally acquire last week. In one of the discussion on the Aardvark web site or MEWE site, there was a discussion of Aluminum Mesh size for use with the EP-20 series of Primer Mixtures. What was reported in those discussions was that there was a need for larger particles to improve both the ignition burn and the flame into the powder. Although I have not progressed to having rounds loaded with powder using this mixture; I am wanting to try and validate that the 75 Mesh Aluminum Powder does or does not resolve the 9 of 10 primers not igniting from Post #2 above.

I will be preparing a Primer Mixture with 75 Mesh Aluminum as follows:

Bismouth Tri-Oxide 5.52 Gr.
Nitrocellulose (Pistol Powder) 2.1 Gr.
Aluminum (75 Mesh) 1.02 Gr.
Glass 0.7 Gr.

[MUSTANG]

One area I am doing Internet Research on is potential "Sensitizers" that I might use instead of Tetracene that was used in EPM-16 and EPM-17.

Goal will be to find some alternative to manufacturing a "Sensitizer" and also avoid adding anything that will make the Mixture a Corrosive Primer mixture. My chemistry background consists of watching 1930's to 1950's Black and White Movies of the "Mad Scientist", a home Chemistry set at the age of 10, and what I have read and digested for the 25 to 30 years. As they say - "He Knows Just enough to be Dangerous"; which is why I am extremely cautious in these endeavors.

[WRideout]

Good work, Mustang. The essence of science is not to prove a point, but to discover repeatable processes. It looks like you are well on your way.

I have been intrigued with things that burn and blow up ever since childhood. In my professional career as an environmental scientist, I made a self-study of explosive and energetic materials that had become waste. One of the few times I made money on something that I had a personal interest in.

Wayne

[MUSTANG]

So cleaning up prior to mixing more EPM-18 version/s; I was looking at the last Mix Ratio (see post #2) I had enough mixture left over for 10 or more Primer Cups. I decided to adjust this some and see if a minor change improved results. I added more Glass to the remaining mixture (an additional 0.287 Grains). This resulted in the following Ratio by weight of components (Based on remains of previous mixture of 3.8 Grains total - with additional Glass Total weight was ~ 4.087 Grains loaded into 10 primers).



Bismouth Tri-Oxide 2.24 Gr.
Nitrocellulose (Pistol Powder) 0.86 Gr.
Aluminum (75 Mesh) .413 Gr.
Glass 0.574 Gr.

Test Firing Results:
9 Rounds – Slight noise above level of the firing pin hitting the Primer Cup.
0 Rounds – Strong Pssssst sound on firing pin hitting the Primer Cup. (None)
1 Round - Moderate Ignition Bang, very slight flame (1/2 inch?) out muzzle of 24 Inch Barrel.


My thoughts for now are that I may add even more 350 Mesh Glass to a new mixture with same ratios as in Post # 1 - but add/increase above that more Glass to hopefully improve the Number of Rounds that will "Go Bang". My thoughts are that the ratio of Glass in the 1920's to 1950's mixtures was greater; it was seen as a sensitizing agent in those mixtures. Although this test did not indicate improvement; it did seem to indicate similar performance. Glass was removed 75 to 100 years ago because of concerns of barrel wear. I have seen a variety of references speculating that the finely ground (such as the 350 Mesh Glass I am using) will provide a minute of polishing to a barrel - but no measurable erosion from abrasives. We must keep in mind this is NOT Aluminum Oxide! It is instead pure aluminum powder.

I once again am trying to avoid the accumulation of even more chemicals and Lab Equipment necessary to produce Tetracene as found in EPM 16 and 17, as well as many other Primer Mixtures. While producing a stable mixture for Primers with a Strong and Consistent ignition; without corrosion or chemical lead hazard risks.

[MUSTANG]

So; I had all of those Primers that failed to fire. The Chemicals were still unused or partially still present in the Primers that failed to Fire. I removed the anvil, scraped the cups of chemical mixture, and used a dental pick to move all the paper foils out of the mixture.

My thoughts drifted back to descriptions of "Filling Cups" from the 1940's era Paper/Manual entitled:
[U]PRIMERS for Small Arms Cartridges[/U By M. J. ALBERT and H. F. OELBERG. (PDF Copy on the Aardvark site): https://www.aardvarkreloading.com/resources/Primers%20for%20Small%20Arms%20Cartridges%20-%20Albert%20and%20Oelberg.pdf

Several of the primer remanufacturing mixtures in the paper/manual, referred to filling the cup - then packing that down - then filling the cup a 2nd time - and repacking. Then followed by a paper foil and anvil seating.

I decided to give that a try using all of the "Salvaged" Primer Mixture from the previous testing. Twice filing and packing did have dramatic results compared to previous tests I conducted in this thread.

Test Firing Results:
0 Rounds – Noise other than noise of the firing pin hitting the Primer Cup.
2 Rounds – Strong Pssssst sound on firing pin hitting the Primer Cup.
8 Rounds - Moderate to Strong Ignition Bang. It was bright for an early winter day, and I did not observe any flame from the muzzle of 24 Inch Barrel; but I believe 8 of the rounds would have resulted in a Good Ignition with Powder and Ball.

I may be on to one of multiple areas to get this mixture to work - without Tetracene (or is it Tetrazene? Will have a future discussion of that in this thread I believe). Hope springs eternal I guess.


PS. This test was using primer mixtures that had 350 Mesh Aluminum in them. The 350 Mesh results in a very "Fluffy Mixture", so when compressed, it may be less volume in the cup than needed for reliable ignition. Wonder what the Commercial Producers are doing with this mixture since they are supposedly using an even finer Aluminum (Reputedly as fine as 1 micron - 350 mesh is about 44 microns).

[lavenatti]

Have you thought about substituting magnesium or magnalium powder for all or part of the aluminum? Either of those metal powders ignites easier than aluminum.

[MUSTANG]

Have you thought about substituting magnesium or magnalium powder for all or part of the aluminum? Either of those metal powders ignites easier than aluminum.

Thanks for the comment. I ordered some magnalium powder this morning to use in testing as a possible resolution to the Aluminum Powder not adequately igniting; and lack of burning on Primer Ignitions.

[MUSTANG]

I tested this morning 10 Primers that were loaded with 75 Mesh aluminum instead of the 350 Mesh aluminum powder. Mixture was:

Bismouth Tri-Oxide 19.5 Gr.
Nitrocellulose (Pistol Powder) 5.0 Gr.
Aluminum (75 Mesh) 3.3 Gr.
Glass 5.0 Gr.

Cups were filled and compressed - One time. (Not twice as described in Post #7 above)
The larger Mesh appears to have had a Minor Improvement over Post #1 and 350 Mesh Aluminum.

Test Firing Results:
2 Rounds – No Noise other than sound of the firing pin hitting the Primer Cup.
3 Rounds – Strong Pssssst sound on firing pin hitting the Primer Cup.
5 Rounds - Moderate to Strong Ignition Bang. It was bright for an early winter day, and I did not observe any flame from the muzzle of 24 Inch Barrel

I am not yet optimistic of the more coarse 75 Mesh as resolving problems. A slight increase in primer ignition does not equate to being reliable ignition; but will continue experimenting.

I may try in a few days charging the Cups with Primer Mix Twice and compressing twice to see if that helps as done in Post #7; using the 75 Mesh Aluminum powder.

Additionally, In a couple of days; I will test 10 Primer cups that I loaded with a 75 Mesh aluminum and primer mixture as described in this Post #10. To this 10 cups; I used a 20 to 1 ratio, of 90% Alcohol and Varnish as a sealer/binder to the mixture. I want to let it dry for at least 48 hours before testing.

[MUSTANG]

Today I Tested 10 Primer cups that I loaded with a 75 Mesh aluminum and primer mixture; PLUS = a I used a 20 to 1 ratio, of 90% Alcohol and Varnish as a sealer/binder to the mixture. I let it dry for at least 48 hours before testing.

Bismouth Tri-Oxide 19.5 Gr.
Nitrocellulose (Pistol Powder) 5.0 Gr.
Aluminum (75 Mesh) 3.3 Gr.
Glass 5.0 Gr.

Cups were filled and compressed - One time. (Not twice as described in Post #7 above)
The larger Mesh appears to have had a Minor Improvement over Post #1 and 350 Mesh Aluminum.

Test Firing Results:
3 Rounds – Strong Pssssst sound on firing pin hitting the Primer Cup.
3 Rounds – Minor Ignition Bang.
4 Rounds - Strong Ignition Bang. It was an overcast and drizzly early winter day, and I did not observe any flame from the muzzle of 24 Inch Barrel.

The use of a drop of Alcohol/Varnish in each cup before seating anvil does not appear to give any significant advantage compared to previous Post #10 Test. These were given 48 hours to dry, so despite being higher humidity I am not seeing an advantage in Formula, 75 Mesh, and Single compaction for Post #10 and Post #11.