Help, I got signs of pressure

gundownunder · Post by **gundownunder** » Thu Mar 20, 2008 4:47 am

I tried three new loads for the 357 today and one of them is causing minor primer flow around the pin strike but with my eyesight I didnt find it till I got home and put my reading glasses on.
So which load is it;
All WW brass
All CCI small pistol primers
125 lead tc with 6.2gr unique is what I use now and its good
the new ones are;
158 rnfp with 5.8gr unique
125 lead tc with 14gr 2400
158 rnfp with 14gr 2400
These all read as mild loads to me and none felt as potent as factory ammo or caused any extraction problems.
If it helps, the 158 and 5.8gr unique couldnt hit paper past 50 yds.

Thanks for any ideas

Tycer · Post by **Tycer** » Thu Mar 20, 2008 5:21 am

I'll venture to say the 14 gr of 2400 caused the flow. Not that it's too hot, but of the loads you have, that one is the hottest.

What rifle are you using? The firing pin hole on my Win 94 357 is too big and allows primer flow on the hotter loads. WSPM primers will really flow and one in a hundred will even be slightly sooty. Headspace could be a thousandths or so better too.

Rusty · Post by **Rusty** » Thu Mar 20, 2008 5:44 am

I'd have to agree. Years ago I loaded 140 grain JHP over 13.5 grains of 2400 and out of my 4" Python it was hot.

Post by **Hobie** » Thu Mar 20, 2008 6:40 am

Tycer wrote:I'll venture to say the 14 gr of 2400 caused the flow. Not that it's too hot, but of the loads you have, that one is the hottest.

What rifle are you using? The firing pin hole on my Win 94 357 is too big and allows primer flow on the hotter loads. WSPM primers will really flow and one in a hundred will even be slightly sooty. Headspace could be a thousandths or so better too.

I think this is your answer.

AndyM · Post by **AndyM** » Thu Mar 20, 2008 6:55 am

For what it is worth...
after much experimentation and trials - I have switched to Lil'Gun for my .357 hotter loads from 2400

Tycer · Post by **Tycer** » Thu Mar 20, 2008 7:17 am

AndyM wrote:For what it is worth...
after much experimentation and trials - I have switched to Lil'Gun for my .357 hotter loads from 2400

I have too. Still get primer flow on all primers.

Grizz · Post by **Grizz** » Thu Mar 20, 2008 7:27 am

Tycer wrote:
AndyM wrote:For what it is worth...
after much experimentation and trials - I have switched to Lil'Gun for my .357 hotter loads from 2400
I have too. Still get primer flow on all primers.

OK, can someone clarify this please? A large firing pin hole can contribute to primer flow too. So is it possible for it to be normal on certain guns?

IIRC, there are older smiths that develop this problem and if IRC the cure is to peen the primer hole to reduce the clearance. Is this so?

If you have 10 different .357s and some of them show that sign and others do not, that would be a better indicator.

But of course reducing the load or switching to lilgun is prudent and called for. Especially if the primer strikes look similar from a number of different firearms.

JimT · Post by **JimT** » Thu Mar 20, 2008 8:22 am

Primers are a VERY POOR indicator of excessive pressure.

It is common to have "primer flow" when other conditions exist. It does not necessarily indicate high pressures.

If you look at the primers from cartridges that blew guns apart, often the primer looks normal.

Starting in the 1930's Lyman published photos in all their loading manuals showing the primers of .30-06 cartridges loaded from low pressure to very high.

You cannot tell, by looking at the primers, which cartridge was 20,000 and which one was 55,000.

If you are loading recommended loads and are getting what seems to be excessive pressures, back the load off 10% and see if it still does it.

Quite frankly, most of the time, it is not pressure.

Again, PRIMERS ARE A VERY POOR INDICATOR OF PRESSURE PROBLEMS. READING PRIMERS IS ABOUT LIKE READING TEA LEAVES.

Tycer · Post by **Tycer** » Thu Mar 20, 2008 8:25 am

In my case, it's the gun. I look at it as normal for it. I get really deep primer strikes and a little flow on any spicy load that flattens the primers. 110, 296, 2400, Lil'gun.... The same loads do not flow in other guns. I could probably stone the pin a little and peen the firing pin hole, but I've shot an awful lot of rounds through it with no change so I probably won't. I could switch to the harder CCI primers, but I probably won't.

JimT · Post by **JimT** » Thu Mar 20, 2008 8:58 am

Tycer wrote:In my case, it's the gun. I look at it as normal for it. I get really deep primer strikes and a little flow on any spicy load that flattens the primers. 110, 296, 2400, Lil'gun.... The same loads do not flow in other guns. I could probably stone the pin a little and peen the firing pin hole, but I've shot an awful lot of rounds through it with no change so I probably won't. I could switch to the harder CCI primers, but I probably won't.

One of my 357's has a long firing pin. With standard hot loads (factory) I get peirced primers now and again.

14 gr. 2400 is not a hot load with a 125 gr. slug. My standard load is quite a few grains above that, even in the long firing pin gun.

gundownunder · Post by **gundownunder** » Thu Mar 20, 2008 10:44 am

Lee recommends 13.9gr of 2400 as a start load for 158gr cast and lists pressure as 34,000 with 15.3gr so its still only a very mild load.
In fact all my loads seem to be in the area of very low 30,000 range, based on both Lee and Alliant data, and thats what has me confused.
If primer flow is not a pressure sign does that make it safe to ignore it?, or what should I do about it?
I have noticed that my Marlin does strike quite a solid blow on the primers, should I try a rifle primer or is there a harder pistol primer worth trying.

JimT · Post by **JimT** » Thu Mar 20, 2008 10:56 am

gundownunder wrote:If primer flow is not a pressure sign does that make it safe to ignore it?, or what should I do about it?

IF it is not locking the gun up or making it hard to rotate the cylinder, and IF the loads are well under Maximum, and IF it is not noticable unless one happens to look closely at the primers ... I would.

"Primer flow" normally describes the displacement of metal. Primer flow from excessive pressures is not just noticable, it jumps out at you. In fact, it can lock up a sixgun or make it extrremely difficult to turn the cylinder.