How much cratering of primers is too much? Pics?

[eclarsen]

I just started working up a load for my 357 Max, 12" Contender and noticed my lightest loads (180gr FNGC, H110) had no cratering, but as I inched up 0.5 gr at a time, I soon started seeing slight cratering or raised edges of primer around the indentation of the firing pin.

Cases extracted easily for all charge weights and none were at maximum charges.  Primers were CCI 400 and did not appear to be "flattened"...just had the ridge around the edge of the indentation.

I've done a search for pictures of "cratering" and the responses for pictures that mimic what I see is "not a problem, fire on".

My Lyman manual has a side view drawing of "cratering" that is a sign of high pressure, but I'd like to see pictures of such. 

Anyone have pictures of "excessive cratering" that would be a sign of over pressure?

Thanks.

[sportclay]

Try another brand of primer.  I have found over the years that primers can sometimes be an unreliable indicator of high or low pressure.  Sometimes the firing pin hole in the bolt or breech face is slightly large and will show cratering and could be interpreted as a "pressure" sign.  Some primers depending on type, manufacturer, lot, will show cratering when pressure is not necessarily a factor.  Do not dismiss the cratering as being a false sign of high pressure.  If it's well flattened and cratered  this might raise my suspicions.  Other pressure signs should be observed such as base dimensional changes.  excessive stretching of the cases.  The best way to tell whats going on is to use a chronograph.  Pressure, for the most part is directly proportional to velocity.  Comparing your handloads to a factory load and published data will tell you if you are pushing the limit for your gun.   Pressure signs are just that, signs, they are relative given the same components  They may or may not indicate unsafe loads.  But do not ignore.  Chronographs are really inexpensive these days and in my opinion no handloader should be without one.  Even if you match a recipe component for component, from a manual using the same firearm it is unlikely the result you see on the chrono will match the printed/published results.  They will or should be close and any radical deviation from the published data should be a warning.  If your chrono results are well under a published load and still show a cratered primer the likelyhood of a slightly soft primer cup may be the culprit.  In the last few years I have found certain brands and lots within certain brands are showing pressure signs when no excess pressure exsists.  Chronograph....

[eclarsen]

A chronograph is in my future for the reasons you mention.

Your comment on large firing pin hole was what people mentioned was the cause for some of the "cratering" that was being asked about on another bb. 

A chrono will tell me the rest of what I want to know.  Thanks for the info.

[Curtis]

I agree with everthing sportclay said about reading primers for pressure signs.  I only respond to caution you on your first impressions using a chrono.  The first temptation after chrono-ing some of your pet loads is to become unhappy with them, either because of lower velocity than you expected or larger deviations.  My advise is this: if you were happy with the load before the chrono, stick with that load (assuming it proves to be safe) and use your chrono to troubleshoot your "problem" loads.  There is nothing to be gained by chasing numerical perfection.

Curtis