Judging pressure in Load Development

[mmorris]

I've been working a while after getting the casting fever to get to the point that I need to work up a load for some Boolits. I'm there now. The reading I've done talks about primer flow and comes down to a judgment call. I got no judgment. You guys got plenty. ;)

The picture below shows the first 20 handloads I have produced (well, minus the two cases that bounced off the tarp & hit the leaves).

I’m looking for guidance in reading pressure indications in the case and primer.

First question: Are any of these showing signs of excessive pressure?
(These loads are below the Max listed in all the references I used to determine powder charge)


Thanks,

Mike

http://castboolits.gunloads.com/attachment.php?attachmentid=12084&stc=1&d=1236569533

[Fixxah]

I am no expert but I would go with either of the 5.2 gr loads. The others look like they deformed the primers. They may shoot great but brass won't last too long.

[dwtim]

I've never seen a CCI 500 crater like that out of any of my guns, but then again, I don't own your gun--and I didn't set the COAL on your cartridges. The load is definitely within the range tested by Vihtavuori, but 9mm is a high pressure round that is sensitive to bullet seating depth.

Do the primers turn out the same with CCI factory ammo? If not, then perhaps something is amiss.

Other than that, it's hard to judge primer flow from the picture.

[missionary5155]

Good morning & WELCOME Mmorris
Pressure... THE best method I know of that does not involve stress gauges and science labs is the "CASE WEB EXPANSION" measurement.
Get at least 5 MAX Factory Loaded bullet for the arm in Question.
Fire the cartrdges in that firearm. With a quality micrometer measure the expanded brass Case Web Area. That is the case area after the grove towards the mouth. With the micrometer you WILL find that area where the case is THE MOST EXPANDED. That measurment is the Max Case Expansion you should NOT go past with your reloads. The 5 MAX load factory cases will give you a good idea what is safe in THAT firearm. Right this measurement down in your loading Data Book.... (Do you have one for this forearm ? ) Now measure your reloads the same way. Remeber you are working in THOUSANDTHS and each .001 increment IS important.
Each firearm is different on it´s capability to withstand pressure. Steel mix, working, shape, mass all come into play.
Just looking at flat primers... is this a hard cup primer? Thickness? It gives you an idea... but my idea and someone else may vary to the destruction of your firearm and worse.
All reloading manuals have a PRESSURE Section... Have you read yours? If not you could be stepping into a real problem. Loads listed in Reloading Manuals are generally safe in MOST friearms. There are some CHEAP made "Thangs" out there nothing is safe in. Also OLD firearms are getting worn and loose and need to have a bit less pressure.
When I am up north I live in Danville. May see ya one day !
Mike in Peru SA

[Bret4207]

When I enlarged the pic I saw cratering on most or all of the primers. Could be a hot load or it could be soft primers. Best to measure as Mike outlined. Primers are a poor way to judge pressure unless you have a long line up of other primers leading up to that point to judge increasing pressure with. And even then, a different gun with a different firing pin and breech face will give different results.

[high standard 40]

Reading pressure signs on a fired case has to take into account several factors.
Cratered primers can be caused by a soft primer cup or an oversize firing pin hole in the breech face or high pressure. I have not found CCI primers to have soft cups. What Mike says about measuring case expansion is important.

Charlie........

[Harry O]

I have never been able to read pressure signs from the primers of the handgun loads I shoot. They don't develop enough pressure -- not even the 9mm luger. If you do see signs, you are probably well into the danger range with them.

Rifle cartridges are different. You can easily see the results of high pressure.

I see rings around the firing pin in almost ALL of the ones you show above. that is normally a sign of pressure. However, since it is on all of them, that makes me believe it is due to an oversized hole that the XXXprimerXXX (should have read "firing pin") goes through. That can cause problems, but it can happen at fairly low pressures. I don't see that the primer is flat near the edge, which is often a sign of high pressure. Also, there is no sign that the firing pin indentation gets smaller with higher loads. That happens when excessive pressure irons out the indentation. It is always (from what I have seen) seen in conjunction with flattening at the edges. It is also sometimes seen with polishing of the case base at the extractor and/or embossing the primer with the backside of the bolt.

In other words, I don't see signs of high pressure in the pictures you posted, but handguns are not the best to read primers on. I would suggest starting lower than the book maximum and working up to the maximum slowly. Then stop.

[44man]

I have to agree with Harry. I would look at the firing pin hole first and then get the head space checked. The edges of the primers are still rounded so it looks like there is no support at the center.
What does the gun do with factory loads?

[FN in MT]

Why not buy a cronograph in order to get an idea of velocity and then go from there? Velocity will vary with the same load barrel to barrel and even between loading manuals but at least you have ONE accurate measure for that particular gun.

I NEVER try to load to the ragged edge of max pressure for any pistol. It's senseless in my thinking. I reload 90% of my pistol or revolver loads LOWER than factory pressures. If a .38 Spcl with a 158 gr slug at 850 fps isn't enough than a 210 or 240 gr from a .41 at 900-1000 will do the job.

FN in MT

[mmorris]

Thanks for the responses. I should have given a little more info in my post, sorry. [smilie=1:

Firearm: Ruger P95DC (new w/ less than 200 factory rounds and exactly 20 reloads)
LEE Classic Turret Press
Lee Carbide 4-die set w/Factory Crimp die
New brass
CCI Small Pistol primers (are these “soft” or “hard” primers?)


All reloading manuals have a PRESSURE Section...

Vihatavouri doesn’t publish pressures - only velocities.:???:
Other powder mfg’s list pressures up-and-down around 32,000 PSI.

Load sources I consulted:

LEE Modern Reloading, Second Edition, p. 534
124gr Lead Bullet
COL= 1.142
3N37 (Start) 5.5gr 1171 fps (MAX) 6.0gr 1234 fps

Vihatavouri Reloading Guide for Centerfire Cartridges, Edition , p.45
124gr FMJ-RN
COL 1.142
3N37 (Start) 5.2gr 1102 fps (MAX) 6.2gr 1243 fps

Sierra Rifle & Handgun Reloading Data, Edition V 3rd Printing, p.737
125gr FMJ
COL 1.090
3N37 (Start) 5.0gr 900 fps (MAX) 6.3gr 1150 fps

Case Overall Length Question:
:?:If the (min) COL is 1.142, should I go with the longest COL that feeds well and is less than the MAX COL of 1.169? For example, use 1.152 or even 1.160 if it feeds OK?

I set COL at 1.152 on the three loads for the Hornady FMJ.
I set COL at 1.142 on the load for the cast WW Boolits.

I will do some tests to get the figures on the expanded brass Case Web Area on some Blazer 115gr factory loads that I have and post the results, along with the numbers for the suspect loads pictured. I will also get some 124gr and heavier factory loads to test.

I will check the firing pin hole more closely (seems to be around 0.079"). The craters on the 5.8gr look like 0.090".
Can't see the firing pin... any suggestions on this Ruger to eliminate excess hole size?

Obviously More Data Required
After I looked at these first handloads, I decided I needed a chrono to gather more info, and I just got a ProChrono Digital. I will follow-up when I get some data (after I go through the Self-Help Chrono training session).

:?:Can chrono data help with pressure evaluation, or is it just going to show consistency from round-to-round in a load development test?

Thanks

Mike

[mmorris]

Why not buy a cronograph in order to get an idea of velocity and then go from there? Velocity will vary with the same load barrel to barrel and even between loading manuals but at least you have ONE accurate measure for that particular gun.

I NEVER try to load to the ragged edge of max pressure for any pistol. It's senseless in my thinking. I reload 90% of my pistol or revolver loads LOWER than factory pressures. If a .38 Spcl with a 158 gr slug at 850 fps isn't enough than a 210 or 240 gr from a .41 at 900-1000 will do the job.

FN in MT

I posted before I saw your response (see end of last post).

I just got a ProChrono and I am off yet another sidetrack on the Road to Reloading.

I'm looking for more info on chrono use and meaning in load development.:Fire:

I also agree that min loads to start with are a good policy (esp for beginners).[smilie=s:

Mike

[gray wolf]

The advise you got about taking measurements was a good thing.
It would be good if we could see some cases from factory loads.
From the pic. it looks like there is not primer flow I/E it looks like the primers have not flattened out as to flow into the slight bevel that is at the beginning of the primer hole--I could be wrong.
My first seat of the paint's guess would be--a slight bevel in the breach face at the point that the fireing pin exits the breach face. look and see if it has a little bevel around the fireing pin.
I hope that is all it is.

GW.

[Maven]

"Can chrono data help with pressure evaluation, or is it just going to show consistency from round-to-round in a load development test?"

Mike, The short answer is no, it can't. As you've said, the chronograph measures velocity and round-to-round consistency (arithmetic means, extreme spreads, standard deviations). Although pressure is directly related to velocity, it is not a perfect correspondence and can't accurately be determined without strain gauges, pressure barrels/universal receivers, etc. Understand too that in pistol cases, small changes in powder weight, powder type, bullet design (bearing surface) and composition (jacketed v. Pb alloy), bullet hardness, bullet to bbl. fit, bullet weight, primer type, etc., will have appreciable effects on both pressure and velocity, sometimes to a dangerous degree. Most reloading manuals discuss this extensively and also provide pressure data along with suggested starting and maximum charges of a given powder/bullet combination.

[mmorris]

Here is a picture of 10 rounds of factory load Magtech 115gr FMC in the bottom two rows.
The others are in the same positions as in the first picture.

It looks like the cratering is a normal pattern for this Ruger P95DC.

The Max Case Expansion I measured on the Magtech came out to 0.3885”
(yea, all ten of ‘em).

The Max Case Expansion on my reloads is:
5.8gr - 0.3890
5.5gr - 0.3885
5.2gr - 0.3875
5.2gr - 0.3880 (WW)

It looks like case expansion follows predicted pressure increases (as powder charge increases). Cast WW seem to cause a little PSI increase, too.

I see that my 5.8gr load exceeds the Magtech by half a thou. Do I need a bullet weight match grain-for-grain to correctly establish the Max Expansion for this pistol?

This is great:drinks: I really appreciate the help.

I’ve really learned a lot in this thread about pressure indicators to look for as I try different loads. I started with the VV 3N37 and I am going to continue working with it before I switch to the other powders I have on hand.

Mike




http://castboolits.gunloads.com/images/attach/jpg.gif

[mpmarty]

Welcome Mmoris;

A slight addendum to what you have already learned.

When measuring case head expansion to judge pressures, it is important to measure the case heads BEFORE firing the factory rounds and noting the difference after they are fired. Try this with several brands and do not use Blazer aluminum cased ammo for these measurements. You're not reloading aluminum and the data gathered from them is useless for your purposes.

Once you get a good baseline on factory loads get new brass of the same make as you tested the factory stuff in and go to testing your handloads for pressure. Once fired or many times fired brass will mislead you as the brass work hardens and the expansion numbers will not be indicative of pressure in the same way new brass is.

Be careful out there!

[38-55]

MMorris,
Cool stuff.. I think some of what your seeing is a 'large' firing pin hole in the face of your slide ( this is not a 'bad ' thing or a defect.. it's just the way the gun is made). Based on your measurements vs the factory ammo I think I'd stick with the 5.5 load for max.. Chronograph your loads and you might be surprised at the speed of em'. 9MM's are peaky little critters and in my experience lead boolits tend to show pressure signs faster ( closer to max charge) than j-boolits do... I think this is due to the lead upsetting to the bore better/faster than jacketed bullets.. thus giving a better seal and a little higher pressure faster..
Oh and don't sweat expansion with lead bullets in the 9mm... just work on your shot placement skills..
Stay safe
Calvin