Primer Temperature Sensitivity

[CA48]

As hand loaders we go to greats lengths to produce consistent ammunition. Reducing as many variables as possible, spending up to many hours to produce a single lot of hand loads, and with every detail of it there is a discussion present. Something I've yet to find much info on concerning primer sensitivity. Living in the Southern U.S. we experience hot temps year round that change velocities with even the most temp stable powders. This leads me to believe that there has be some effects with high temps and primer choice. In the constant strive to reduce all variables of hand loaded ammunition in hot temperatures I would like to do some simple testing in the future as I would think results will vary the highest in small capacity cartridges. There's seems to be almost no testing or info on the web towards the subject. Has anyone out there tested primer sensitivity with large and small rifle primers or know of any testing done?

 

[J E Custom]

As hand loaders we go to greats lengths to produce consistent ammunition. Reducing as many variables as possible, spending up to many hours to produce a single lot of hand loads, and with every detail of it there is a discussion present. Something I've yet to find much info on concerning primer sensitivity. Living in the Southern U.S. we experience hot temps year round that change velocities with even the most temp stable powders. This leads me to believe that there has be some effects with high temps and primer choice. In the constant strive to reduce all variables of hand loaded ammunition in hot temperatures I would like to do some simple testing in the future as I would think results will vary the highest in small capacity cartridges. There's seems to be almost no testing or info on the web towards the subject. Has anyone out there tested primer sensitivity with large and small rifle primers or know of any testing done?

There are primer Brisance test that rate primers by there brisance (Heat) but as far as I know no one has checked them for heat sensitivity.

The test stand used in the link would be a good way to do this because it doesn't need powder and only measures the primer itself. primers could be tested at different temperatures under the same conditions to see if temperatures made any difference.

Primer Testing Reference

There is very little primer compound to make any difference, but it would be very interesting to see if there were any differences with temperature changes. I think it would be educational for sure and might produce some interesting data.

keep us posted on your findings. who knows, it may start a whole new debate.

J E CUSTOM

 

[Dosh]

48, living here in Az heat is a big concern with everything. We need to keep components indoors. We have not encountered any variance in primers once loaded due to temps. However, I have a good friend who lives in northern Ca on the coast and reported multiple problems with primer storage due to humidity. He now vacuum seals primers and keeps opened 100's in plastic bags. This is the only atmospheric effect I've heard of concerning primers. A controlled temp test for primers seems like a good one to try. Results could be interesting.

 

[CA48]

JE, that is an interesting link. The test stand used would be convienant and save a lot of time but I feel a test measuring velocities of live rounds would provide me with more usable data. By watching for any significant deviation in velocity between temperature ranges.

 

[CA48]

Dosh, as JE stated there is very little primer compound and the extreme temp differences may not change velocity more than a few fps in reality but on testing will tell.

 

[THEIS]

Hello,

Here is link to numerous primer testing done back in 2008 at Picatinny Arsenals' Armament Research, Development and Engineering Center.

Not "exactly" what you looking for BUT it is a great read
http://www.dtic.mil/dtic/tr/fulltext/u2/a482173.pdf

THEIS

 

[J E Custom]

JE, that is an interesting link. The test stand used would be convienant and save a lot of time but I feel a test measuring velocities of live rounds would provide me with more usable data. By watching for any significant deviation in velocity between temperature ranges.

The only reason I mentioned the action device was that It did not use any powder, primers could be inserted very fast and fired in order to maintain the temperature, the primer pocket could even be lined with a non conductive material that would not change the temperature to fast. Powders ARE heat sensitive to some degree and would/could skew the numbers in my opinion.

When I do component testing I try to eliminate as many other components that could interfere with the end results. and only make one change at a time.

This is just my opinion and the way I would do the test.

J E CUSTOM

 

[CA48]

The only reason I mentioned the action device was that It did not use any powder, primers could be inserted very fast and fired in order to maintain the temperature, the primer pocket could even be lined with a non conductive material that would not change the temperature to fast. Powders ARE heat sensitive to some degree and would/could skew the numbers in my opinion.

When I do component testing I try to eliminate as many other components that could interfere with the end results. and only make one change at a time.

This is just my opinion and the way I would do the test.

J E CUSTOM

I agree it would save a lot of time and much could be learned from the data it would produce. I just prefer to get velocities so I can tell if I'm going to see any major deviations that will cause any change in the elevation of my firing solution at long range. I've thought about the chamber heating up as well and it would skew numbers if I were to fire more than one round at a time. I was planning to shoot one at a time and let the chamber cool back down to ambient temperature whether by waiting long periods or cooling the rifle off in a deep freeze. I have have an infrared thermometer to keep track of chamber temperature. I can place the theremometer up close to the ejection port and point the laser directly inside against the center of the chamber wall.

 

[Predator 22]

I agree it would save a lot of time and much could be learned from the data it would produce. I just prefer to get velocities so I can tell if I'm going to see any major deviations that will cause any change in the elevation of my firing solution at long range. I've thought about the chamber heating up as well and it would skew numbers if I were to fire more than one round at a time. I was planning to shoot one at a time and let the chamber cool back down to ambient temperature whether by waiting long periods or cooling the rifle off in a deep freeze. I have have an infrared thermometer to keep track of chamber temperature. I can place the theremometer up close to the ejection port and point the laser directly inside against the center of the chamber wall.

How would you determine if the velocity change was from the powder or primer? I would be very curious to see it done were you could show heat and pressure over time on a graph.

 

[CA48]

How would you determine if the velocity change was from the powder or primer? I would be very curious to see it done were you could show heat and pressure over time on a graph.

I would think it would be best to use non temp sensitive powders to eliminate large velocity swings. And if all components are kept constant (powder charge, bullet, seating depth, neck tension) and only the primer is changing then all deviations found should correlate with the different primers being used.

Something tells me results may vary significantly depending on cartridge size and severity of overbore, so it would probably be better if a few different cartridges were tested.