Lawyer proof data

[Markk9]

I was looking for some load data for the 9mm comparing European and American data to find the highest velocity for a 155 gr FMJ. All the American data I have is about the same, but Vihtavuori Oy’s reloading guide 2nd Edition lists a Hornady 115 HP/XTP doing 1423 fps out of a 4in barrel with a load of 7.9 grs of 3N37 at 36,300 psi. I would really like to try this load out, that bullet is moving. Before I move on, the rest of data for the above load is: 4” barrel, 1 in 10 twist, CCI500 primer and Lapua case, the starting load is 7.2 grs of 3N37 with 1340 fps @ 29,000 psi, the max again is 7.9 grs of #n37 with 1423 @ 36,300 psi. Being the good handloader that I am, I try a cross reference using Vihtavuori Oy’s reloading guide 5th Edition. Like above the rest of that data is: 4” barrel, 1 in 10 twist, WSP primer and Remington case, and same bullet Hornady 115 HP/XTP, the starting load is 5.8 grs og 3N37 with 1182 fps @ 24,900, the max is 6.9 with 1322 fps @ 33,300 psi. The number just didn’t add up in my mind, the starting load in the 2nd edition is .3 grs over the max load in the 5th edition. If this is not lawyer’s keeping the load data down I don’t know what is. I think I’m going to try and work up a load using the 2nd edition data in a beretta 92FS stainless with a 5” barrel.

Mark

[bfoster]

Markk9... The test protocol used by VihtaVouri (CIP standard) varies from the U. S. protocol (SAMMI standard).

Bob

[WESHOOT2]

Gray Area says "screw SAAMI".

[Art Eatman]

Gray area say use common sense.

You look for signs of over-presure, and consider how well any particular pistol supports the brass. Some chambers work well with CIP standards, I imagine. I've read here at TFL about some pistols with lesser support, so the SAAMI standard should be better.

Granted that I'm mostly rifle-oriented, but a reasonable rule of thumb is to use "hot loads" for situations where you don't shoot that load very much. A deer load, for instance; in pistols, it would be your carry load for self-defense.

For punching paper or tin cans, there's just no point in creating the extra heat, stress and wear of full-house hot loads.

A Delta Elite full of hot loads is a wonderful self-defense package. If I'm gonna "work out" and shoot a few hundred rounds of practice, I'll use a regular Gummint Model .45ACP with IPSC loads.

$0.02, Art

[Walt Welch]

Several years ago the Winchester company markedly decreased the powder charge for the 9 x 19 from one edition of their reloading manual to the other. This was a result of changing from the less accurate copper crusher method of measuring pressure to the piezoelectric method.

35 years ago the Hercules company markedly decreased the data for Bullseye in 12 ga. shotgun loads. This was a result of simply retesting loads and getting different data. I even sent them a letter, saying I had reloaded some shells according to the earlier manual; are they now unsafe? They answered yes.

Another reason for change in data is the change of components. I was reloading some Rem 115 JHP bullets in 9 x 19 several years ago; I noticed that the mouth of the hollow point looked different. I miked the bullets, and found that the new ones were 0.035" longer in OAL, with an identical ogive. Loaded to the same OAL, there would have been 0.035" less room in the case; enough to make the pressure skyrocket to dangerous levels. A powder manufacturer using new components may well come to the same conclusion, and reduce the recommended load.

Changes in powder data have nothing to do with lawyers and everything to do with problems from change in components, dimensions of test bbls, and other variables.

Be careful.

Walt

[Markk9]

I'm bringing this topic back from the dead. I have some time to play with this. Boy, is time hard to come by with a new (1st) baby around.

Last night I loaded up some rounds. I using Win cases, Win 115 RN bullets, with CCI 500 primers. The charges were all weighted, I started at 6.3 and went up .2 to 7.7. I plan to shoot them today over a chrony. I will post the results tonight.

Mark

[Markk9]

Here are the results:

Win case/Win 115 RN/ CCI500 all were 20 rounds of each.

6.3 VV 3n37
Average Vel: 1153
Extreme Spread: 182
Low: 1074
Hi: 1256
Standard Deviation: 48.27

6.5 VV 3n37
Average Vel: 1191
Extreme Spread: 106
Low: 1120
Hi: 1226
Standard Deviation: 32.08

6.7 VV 3n37
Average Vel: 1200
Extreme Spread: 100
Low: 1142
Hi: 1242
Standard Deviation: 27.99

6.9 VV3n37
Average Vel: 1242
Extreme Spread: 77
Low: 1199
Hi: 1276
Standard Deviation: 20.22

7.1 VV3n37
Average Vel: 1253
Extreme Spread: 92
Low: 1212
Hi: 1304
Standard Deviation: 29.33

7.3 VV3n37
Average Vel: 1296
Extreme Spread: 58
Low: 1273
Hi: 1331
Standard Deviation: 14.86

7.5 VV3n37
Average Vel: 1327
Extreme Spread: 45
Low: 1310
Hi: 1355
Standard Deviation: 12.16

7.7 VV3n37
Average Vel: 1325
Extreme Spread: 51
Low: 1296
Hi: 1347
Standard Deviation: 13.77

[Peter M. Eick]

So Art,

Lets get real specific here.

What exactly are the pressure signs you would use for a pistol round of low pressure ie (for example): the 45 acp and of high pressure ie: the 10mm or 40S&W to determine what is overpressured?

I am not trying to be a pain, but this is a serious topic that "seems" to be glossed over here. I personally like to use pressure ring data, but that is darn hard to measure accurately with the mildly expansive 45 vs. the much more expansive 10mm.

[labgrade]

I'll take a stab at it. You did ask what time it was, dincha?

Secifics is for your firearm & that one only - even consecutive serial numbers to be completely accurate but in tolerances probably not measurable.

Each firearm will require careful load development to reach maximum for that one specific firearm.

The "pressure ring" you mention, I'll take to be measuring the case head just prior to & again agter firing. Works to some extent, but mainly with never fired brass as each subsequent firing work hardens the brass causing less expansion.

For revolvers, sticky extraction can be a sign of over pressuring.

For any cartridge, very flattened primers is a sure sign you are getting into that grey zone. Note that primers flatten out as a normal result of firing, but should have a distinct radius from this (bolt face) flat towards their sides.

Pierced primers may be a result of a "defective" firing pin - one that's too sharp, but would be noticable on all loads. If you're seeing pierced primers (when not normal) you need to back off.

I'm with Art in that personally there's no sense in beating your firearms & you (at the added expense) of "magnun loads" unless required for a secific task.

If I've multiple shooters for any given caliber, I'll work up loads that work well in all of them.

[Peter M. Eick]

I agree with the limits of the pressure rings, especially on like 380 or 45 acp rounds where the pressures are so low.

The problem is that pressure reading seems to be a "black art" best practiced when the moon is full. Ok, so I am kidding, but just a bit.

I use a sort of multi-stage. gut feel, sort of pressure measurement, and yes I almost never go beyond a "book" load.

But my question is more to the point. If I read that someone is using x.x powder with a particular cartridge, I immediately wonder about how they knew it was safe. Yes it fired and nothing blew up, but how do they know it did not exceed SAAMI specs?

Yes I accept that different versions of the same gun have very different responses. My 3 P7's proved that.

The point is being precise how we determine pressure for all pistol reloads. I am not sure it is a very accurate scientifically repeatable method. It is sort of by feel, and the scientist in me cringes at this. Well everyone has their pet peeve, this just happens to be mine.

[WESHOOT2]

Screw SAAMI; their data/limits are lowest common denominator.

Next, I like 'safe' as much as anyone (repeat after me: "liability insurance").

And even more important is the "...but not always..." philosophy REQUIRED to remain safe, because all guns are always different.

Modern guns in good condition can be loaded safely past most of the SAAMI specs, BUT NOT ALWAYS.
European standards, while higher, are not absolute, either.

Common sense and the black art of reading pressure signs are mandatory as you push loads ever faster, and a good understanding of risk is helpful (so you're not pissed when your gun grunts).

Mapping the powder/velocity curve seems very helpful (chrono required), and measuring cases can add to that, but at some point one must admit to oneself that one is guessing.

And how can I know how YOUR gun will perform?
Will my "Gray Area" load be safe in YOUR gun?
Is YOUR gun in safe mechanical condition?
Does YOUR gun have a tight chamber/close lands/undersized bore/etc.?
Will YOUR GUN be fired in extreme hot/cold temperatures?

So many variables, and I'm with Art and the others: be safe, go slow, observe carefully.
At some point it's 'enough'.

[Peter M. Eick]

Weshoot2,

I am not disagreeing with any of the conclusions, obviously safe is better then sorry.

My point I am trying to get to is what techiques for pressure signs are we all using? And what science backs them up as reasonable and safe.

This is a more philosphic discussion then anything else.

No hard feelings to anyone I hope.

[WESHOOT2]

I stop when my chrono tells me the charge weight/velocity relationship goes awry.
Then I back off.

Then I try it again, with some small variation in the load to get another read.
And again.

Etc., trade secrets, personal, private, old data, in my cluttered head..........

IN YOUR GUN you can also make case measurements to provide you with the specific expansion from your chamber. Use new sized cases for these tests.

There's more..........

[Cheapo]

Warning--I'm going to be rude here.

DUH! Factor alert! The V-V data substitutes BOTH cases and primers from the earlier impressive speeds to the later and more conventional speeds.

And did anyone notice that the pressure was also LOWER?

The difference in velocity is "only" about 100 fps, which might seem minor but can result in very bad juju (pressure-wise), depending on the rest of the components/caliber/pressure standards, etc.

Then consider the rather extreme range of extreme spreads in the tested velocities--far beyond the .05% or so instrument variations which make some small velocity differences most inconclusive.

IIRC, the US makers like to load 9mm to something like 33,500 mean average or whatever, and 35,000 peak (that means no individual load above that measurement..?..)

3,000 psi could very well mean 100 fps--but random instrument variations could make the averages 25 fps or more above or below what's reported, depending on the sample size and the load's adherence (or lack thereof) to the statistical bell curve.

SOOOO, notice that your measured data resulted in much smaller extreme spreads at 7.3 gr. That is a clue.

Notice that the average velocity (yeah, it's a small sample!) went down from 7.5 to 7.7.

That is another clue, folks!

If primers radius out about the same (or w/less pressure signs) as factory loads using those same primers in that same gun, I'd stick with 7.3 to 7.5 gr., and avoid the 7.7.

If you have changed components, using the "load to velocity" approach can still create out of spec pressures.

How much of YOUR safety margin do you want to use up? I suggest that the more rounds you plan to shoot, the more scrupulously you MUST try to keep the loads within specs.

Seems like too many of us are ignoring the obvious in an effort to justify hot-rodding the loads.

Remember, the lawyer will NEVER have a case without a BLOWN UP GUN OR SERIOUS CASE FAILURE! Lawyer-proof, or blow-up-proof?

You decide

[WESHOOT2]

Has anyone noticed that I am not entering the Vihtavuori Oy "#1 vs #2 whatsup widda pressure?" discussion?

Lawyers have NOTHING to do with it; it's a "more accurate representation of actual ammo" thing........

I might suggest that Vihta changed their data because their data changed.

Anyone else here remember when Frank James whined (maybe legitimately) that 3N37 blew up one of his fav sub-guns?

[Clark]

Vihtavuori 1st edition:9x19mm 4" barrel, 147 gr, 1.142", 6.1 gr 3N37,1152 fps 36.3kpsi
Vihtavuori 1st edition:9x19mm 4" barrel, 147 gr, 1.142", 5.7 gr 3N37,1140 fps 36.3kpsi
Vihtavuori 1st edition:9x21mm 4" barrel, 147 gr, 1.161", 6.6 gr 3N37,1227 fps 42.8kpsi
Vihtavuori 3rd edition:9x19mm 4" barrel, 147 gr, 1.142", 5.2 gr 3N37,1066 fps max
Vihtavuori 3rd edition:9x21mm 4" barrel, 147 gr, 1.161", 5.5 gr 3N37,1120 fps max

I have experimented a couple grains higher than the 1st edition, just to see what level the case bulge and kaboom occured at:
http://groups.google.com/groups?q=3N...ing.cs.umd.edu