It seems like a good idea...

[Mr_Flintstone]

A friend and I were talking the other day, and the topic of load development came up. After talking a while we came to the conclusion that some reloading component company should make a set of load development primers. Let me explain...

We all know that when loading hot loads we can get flattened primers; but by that time, we’re probably way over pressure in a lot of cartridges. It would be nice if someone made numbered primers that would flatten at a variety of pressures; to be sold only for load development and not for general use. For example, in loading .357 magnum, I’ve seen primers start to get a little flat, but I’ve never seen a .38 special primer start to flatten, even when loaded really hot. If there was a type of primer that would flatten out at (or around) a given set of pressures, you could develop your load, and switch to standard primers when you were done testing.

I know there’s probably a reason why this has never been done, but it seems like it would be a good idea... but maybe not.

 

[orionengnr]

Seems like it would be very expensive to do (R&D-wise) and with an infinitesimally small market (and return on investment).

 

[edwardware]

The appearance of primer flattening is more sensitive to excess headspace and pocket chamfer shape than it is to pressure.

Yes, you read that right. I can setup a cartridge to run ~half design pressure, and produce completely flat flared primers that are indistinguishable in appearance from overpressure primers.

Inexpensive strain gauges are much simpler and more reliable.

 

[rfwobbly]

It's called a chronograph.

 

[mcb]

It's called a chronograph.

And a copy of Quickloads.

 

[buck460XVR]

It's called a chronograph.

And a copy of Quickloads.

....or just following the recipes in your manuals.

 

[mcb]

....or just following the recipes in your manuals.

Sometimes there is no manual and instead of flying by the seat of your pants (or giving up), Quckloads, a good Chronograph, careful measurements and proper load development can give a hobby reloader a measure of feedback not easily attainable outside of a test lab.

 

[higgite]

A friend and I were talking the other day, and the topic of load development came up. After talking a while we came to the conclusion that some reloading component company should make a set of load development primers. Let me explain...
.
.
I know there’s probably a reason why this has never been done, but it seems like it would be a good idea... but maybe not.

You couldn't afford it. Loading manuals are much cheaper than pressure calibrated primers would be.

 

[edwardware]

It's called a chronograph.

A chrony is a pretty lousy way to measure pressure. The variation between an exceptionally fast bore (tight and smooth) and a slow bore (loose and rough) can be 5%.

Additionally, it tells you absolutely nothing about peak pressure (which is what breaks the gun, or not), only average pressure during barrel transit.

 

[mdi]

Since I rarely go to max powder charges and don't rely on fired primer appearance, I have no worries about high pressures in my guns. But, if I were to want info on what's happening in my guns I might try Pressure Trace.
https://www.shootingsoftware.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=RSI&Category_Code=PT

Pressure sensitive primers may sound like a good idea on the surface, but in real life the development of pressure sensitive primers would be a huge undertaking with way too many variables (as mentioned above headspace and chamber variations). IMO...

 

[Demi-human]

Not to mention all the burned off firing pins and etched bolt faces...

 

[mcb]

So on a related idea to the OP but for shotguns. YMMV on this idea greatly but I liked it.

I found a pressure sensitive film from Fuji (https://www.tekscan.com/products-solutions/pressure-sensing-film/fujifilm-prescale-film). It is used in a variety of industries to measure contact pressure. Things like roller contact in rolled material processing or die closures in the injection molding industry, etc. You expose the film to pressure (crushed at the interface between to objects) and the film would turn colors to indicate the localized pressure.

I would take small piece of the film and apply it to my reloaded shotshell and then fire them. To make my estimations of pressure more accurate (and being partial color blind) I would scan the resulting pressure film samples into the computer and use photo editing software to make fairly accurate optical comparison of my test films to the Fuji published color key. Fuji has a specialized software/hardware to do this but I had good results with a decent quality flat bed scanner, photo editing software, and a Excel spreadsheet. I pressure tested a fair number of published reloading recipes that included pressure data and it did a remarkable good job at matching the published results.

I shopped the idea around a few places and never got any interest. I don't think the shotgun reloaders are nearly as interested in pressure as rifle and pistol reloaders and in reality there are only a few of us hobby reloaders in general that are interested at all in measuring pressure at home. Most reloaders are content with published recipes.

All though there are versions of the films that could handle most pistol cartridge pressures. In practice I found there is insufficient clearance to apply the film to the case and still get it to chamber easily in most cases. Semi-auto actions add other complication to damaging the film before measure. I did all my shotgun testing in manual actions. They do not make a version that goes high enough pressure range for most rifle cartridges and again the clearance for the film would be an issue.

It was a fun experiment and might be useful in the future if I even get back into using shotguns.

 

[rfwobbly]

A chrony is a pretty lousy way to measure pressure.

Agreed. But I can't afford test barrels for 8 calibers and all the computerized pressure test equipment, so I think I'll stay with the next best thing.

 

[LiveLife]

Sometimes there is no manual and instead of flying by the seat of your pants

My first no published load data load development was with Promo ... referencing Red Dot load data since Alliant indicated they were at same burn rate, so to use Red Dot load data by weight, not by volume - https://www.alliantpowder.com/products/powder/promo.aspx

It was scary for me but many of my friends wanted me to be the guinea pig because this was during the component shortage and Promo was available when other powders were not.

While Promo was snappy for 40S&W, for 9mm and 45ACP, produced very usable accuracy. It was the cheapest usable pistol powder that metered like Unique - bad.

I guess our whining to make Promo meter better got heard by Alliant Powders because as Paul from Alliant reported, newer lots of Promo has been reblended with different, more round flakes and now meter much better - https://www.thehighroad.org/index.p...blended-promo-for-more-accurate-loads.841097/

And due to fast powder burn that fills the case well for easy 100% fill loads not affected by slam powder forward position firing, great powder for PCC.


My second no published load data load development was with IMR Red, which has no loads for pistol and gun didn't explode and I still have my fingers - https://www.thehighroad.org/index.p...ectan-ba-9-5-ba-9.817796/page-2#post-10520702

Be safe and thread carefully when going blind (But it's so much better to just follow published load data).