Primer Flow- Just curious

[danman00]

Newbie question guys and forgive me if its a stupid one but I'm still learning. I'm relatively new to loading ( for several months now) but can anyone define what primer flow is? I've seen many references in these forums as to watching for primer flow when upping your powder charge while trying to make PF. I'm assuming it has something to with blowing the primer out of the back of the casing if your load is too hot. I'm curious and cautious as the reason I'm asking is I primarily use range pickup brass with no clue as to how many times some of my cases have been fired. I've never had any misfires or failures so far due to some paranoia on my part as continually run into brass that the primers sink or seat way to easily or way to hard. It's not that many I suppose, maybe a couple two or three for every hundred. But if it doesn't feel right when seating with my RCBS hand primer loader, I toss em. But anyway, what do you guys mean exactly when you say to watch for primer flow?

Thanks, Dan

[Hi-Power Jack]

What caliber are you loading? How hot? What powder and bullet are you using?

BTW - no such thing as a "stupid question" - you should have been around 5-6 years

ago when I first joined - those were almost "stupid questions".

Better safe than sorry.

Spend a half hour one day reading the old postings here on BE - go to Forums - then to

Reloading - then to whatever caliber you're reloading - you'll get LOTS of good stuff:)

BTW, do you have a chronograph?

Edited April 9, 2014 by Hi-Power Jack

[danman00]

I'm not having any issues per-say Hi-Power Jack. I was just curious as to the true meaning of primer flow. I load 9mm, .40 S&W and 45 ACP. No I do not have a Chrono yet.. but its my next purchase.

[Amerflyer48]

Primer flow is the primer material flowing back into the firing pin hole around the firing pin and/or filling out the perimiter of the primer pocket across the breech face end of the casing.

normal primer hit has just the dimple of the firing pin

higher pressures and "flow" would have the dimple with a tiny ridge around the dimple and possibly flattened edges whenre the primer meets the primer pocket along that edge instead of the slight turn in that an unfired or lower pressure round would show.

this shows all sorts of primer issues just keep in mind we do tend to run higher pressures depending on what caliber and PF we run, this is why alot of folks around here use SR primers in the .38Supers etc. thicker cups will resist flow better and most of the time the guns aren't stock and are built to run hotter

bottom of the page shows 3 levels of a 9mm for comparison.

http://stevespages.com/diagnosingproblems.html

Edited April 9, 2014 by Amerflyer48

[ttolliver]

It's not critical, but some of us OCD types sort brass by headstamp. If you do that you'll discover that S&B brass all has that tighter primer pocket that feels like a catch when priming with the hand tool. I assume they're putting a crimp on the primer like military brass uses.

Anyway, if you're not sorting that 2 or 3 per 100 might just be S&Bs or milspec brass in the batch. For my part, I sort all my brass and just use S&B last because of that minor irritation. But it absolutely gets loaded and it shoots just fine.

If you have military brass sneaking in, that can create a bit more of an issue. It's all thicker walled leading to less interior volume. So the same charge in military brass will get you higher case pressures and so on.

The only time I ever felt like had slight looseness in pockets was some very old, tired 45acp. But looseness is generally not a problem I ever really have.

[ropsitos]

I use one of the primer pocket go/no go gages from ballistic tools.

Because I wet tumble I decap first, so after tumbling its really quick to sort the cases using the go side of the gage while watching tv.

If the go side goes in way to easy I check it with the no go side. Usually it's just a case that was swaged. Haven't found a case that the no go would go into.

I did find some tight pockets that I never would have visually id'd as crimped or too tight.

Saves me headaches on the press and I also use it to check if I've cut out enough of the crimp

[danman00]

Thanks for the info guys. I am not sorting by headstamp. Maybe I should.

Generally, I'm noticing that the tightest primer pockets are from the S&B and federal brass. They fire just fine but when priming using the RCBS hand tool, I feel a slight "ker chunk" (like my technical term?) when the primer seats. It makes me nervous. But then again, maybe its the tool or the CCI primers im using. Who knows.

Regardless, I now what to look for when watching for primer flow.

Thanks again