primer pressure gauge?

[terry_g]

I was taught that the primer was a good indicator of pressure. A very much flattened out primer indicated very a high pressure.
I took my 12FV .223 Savage and my home made rest to the range today. I had purchased a quantity of Winchester and Federal ammo. The Federal ammo worked quite well while the Winchester ammo is not near as accurate. When inspecting the spent cases I noticed that some of the Winchester primers had flattened out considerably more than others. Is this just plain old poor quality?

Terry

 

[savage express]

In this months Handloader mag, author talks about primers flattened due to head spacing.

 

[yodave]

Terry I bought some of that Winchester ammo and got the same results. Looking at the necks it seams like alot of them were bulged from the crimping stage, some of the crimps looked really heavy as well. I don't think I have to primers that looked the same after I fired the box off, and I can't take a picture because they have been resized and reloaded already.

 

[stubblejumper]

Primer flatness is a very poor way to try and estimate chamber pressure.

 

[shredder0]

Yup. Primers can be flattened or cratered from a variety of factors. Pressure is only one of those factors. You simply can't read pressure reliably from looking at primers.

 

[Ron AKA]

Primers are an indicator of pressure, but you do have to factor in the type of primer, and other pressure signs. Primers are not all the same thickness, and the thinner ones will flatten and crater easier than thicker ones. So, you do have to know the primer type. See this link for more info:

Primers and Pressure

Your primers are showing issues. And I would agree that the one on the right is showing more pressure. Does seem to reflect on quality of the load. If you handload I would suggest you try some CCI 450, BR-4's, or Remington 7 1/2. They are thicker. I use BR-4's on some fairly stout loads and they look perfect -- not at all like your photo.

Other signs of pressure are an imprint on the brass from the extractor recess, or sheared imprint (more pressure), gas leak around the primer, and enlarged primer pockets. Also you will feel a sticky lift on the bolt.