Pressure Signs?

Peter M. Eick · February 13, 2000, 02:42 PM

As a follow up to the post on reloading manuals, I am always curious what techniques everyone uses to determine pressure or more accurately too much pressure in handguns.

I am currently using the micrometer pressure ring technique (as described in Pet Loads) and comparing the expansion of a reloaded case to a factory round in the same gun. By extrapolation if I have the same or less expansion as a factory round in my gun, I should be safe.

Let me add that I also check every load with a number of modern reloading manuals to make sure that I am not violating max loads on any of them.

Comments? or alternative ideas?

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[This message has been edited by Peter M. Eick (edited February 13, 2000).]

bfoster · February 14, 2000, 10:13 PM

Peter... Because of variation (both in hardness & weight) within each lot of brass and the gradual trend we have seen within the past few decades to stronger case design in the head and adjacent portion of the case I place much less faith in measuring expansion rings than I used to.

I'm not saying that I believe measuring expansion rings to be entirely without merit, but I am sure that in some "hot" loads, the difference between a "safe" and "borderline" measurements is less than it used to be- that is there is less growth per unit of pressure in most lots of brass than there used to be.

Assuming (as you state) that you are using current manuals, and assuming that you choose sensible data for the arm in question, I see no problem in using the published data.

The "rub" comes when a new powder is introduced. It can take years for data to be published in multiple sources, and by then the powder may be obsolete. The Oehler M43 makes working up a load for new powders, or powders for which there is little data available an easy task. Bob

Art Eatman · February 15, 2000, 10:59 AM

For pistols, I don't load maximum with fast-burning powders. I'll only load max or near-max in .357 and .44 Mags, but they are shot through a Ruger GP 100 and a Redhawk. I guess my own version of safety factor is to stay a bit below the data-books' maximum loads.

I compare various books; there are occasional changes over the years as to just how Maximum is indeed Maximum.

Call me lazy, I guess...Art

Peter M. Eick · February 15, 2000, 06:06 PM

I tend to agree with both of you.

The differences I have seen using pressure rings are not as pronounced as before (say 10 to 15 years ago). I was more curious just to see how others are dealing with the same problem.

My current technique is to use the average maximum for a particular bullet weight of all of the major manuals and take that as my absolute max. I then usually start off about 90% of that and work up to 95 to 100% depending upon the accuracy and pressure ring data.

About the only rounds I run full out are my 380 auto using 88 and 90 grn jhps and my 10mm in all bullet weights. I usually back the 40's and the 38 specials to at around 90%. And I run my 45's about about 100% because of accuracy. I am still learning about the 357 sig, so right now it is more like 90%.

I will be curious to see what others have to say.

alan · February 16, 2000, 04:51 PM

Peter:

As you have liklely noted, a manual dating back 20 or so years, and this year's manual will not give the same loading data, likely a result of the antics of liability lawyers.

Having said that, the method you described sounds as if it would make sense. Speaking personally, I have used a particular load in 45ACP for years, never measured case expansion, nor have I lost cases as a result of loosened primer pockets. This load, using Red Dot moves a 200 grain SWC bullet at 900+ f/sec, accurately.

While a contemporary manual might look agast at this load, Red Dot hasn't changed in 80 or so years, the pistols certainly haven't either, so what's different? Liability Lawyers, and personal irresponsibility.

Hope the above offers something to think on.

skipperJ · February 17, 2000, 07:56 AM

I rarely load at maximum, work up my loads from minimum and I check for pressure signs by looking for any flattening of the primer.

bfoster · February 17, 2000, 09:13 AM

alan... If you have some twenty year old .45 ACP cases you might find it interesting to check internal case capacity against current brass. In general, the brass being made now has less internal volume than did older brass. Because it is designed for relatively low pressures, the change averages much less in .45 ACP than you'll find in some high pressure rifle cartridges such as the .270 Winchester. Bob

bfoster · February 17, 2000, 09:28 AM

skipperj... While primer inspection often does show some correlation with pressure there are many conditions which can cause flattening of primers which have little to do with peak pressure. On the other hand, some primers available today will show only modest flattening at 70,000 psi. In the absence of a device such as Oehler's M43 I'd suggest measuring brass by one of several techniques described in the literature- Hornady's Loading Manual and Waters Pet Loads contain two approaches. Any time you observe primer pocket "loosening" or marks on the case head which correspond to any feature of the bolt face it is time to back off considerably. Bob

skipperJ · February 18, 2000, 10:39 AM

<P><I>Any time you observe primer pocket loosening
or marks on the case head which correspond to any feature of the
bolt face it is time to back off considerably. Bob </I><

O.K. Bob, So you do agree with me that primer inspection can be used to determine pressure signs? I've been reloading since 1959 and have never had a problem with pressure.

jtduncan · February 18, 2000, 02:35 PM

Go to your local bookstore and just check out the "ABCs of Reloading" or the "Metallic Catridge . . ." book with a bunch of reloading equipment on the cover. all the answers are there.

------------------
The Seattle SharpShooter

bfoster · February 18, 2000, 04:25 PM

skipperj... Given that (I sincerely hope) you don't want to operate in the 70,000 psi range, and given that some current primers don't show much flattening, flow around the firing pin hole, or boltface mark transfer at 70,000 psi, I'd strongly suggest that you supplement primer "reading" with other observations. Bob

wildcat · February 23, 2000, 03:11 PM

Im surprised no one mentioned velosity.I use most of the mentioned methods but I always chronograph a new load.I figure if I am getting more velosity with my components than the load book specifies then I am also getting more pressure.With the price of chronographs under $100.00 I would not be without one.

Nukem · February 25, 2000, 09:59 PM

Primers,, not reliable as a pressure sign on their own. I think many have seen some brands of primers that flatten and flow around firing pins on perfectly tame loads.
Other times, when you know the load is getting up there some will never flatten. Use all the indicators you can.
:-o

WESHOOT2 · February 27, 2000, 11:42 AM

I try to get the primer to blow, then back off slightly.

Not safe or recommended, but I'm nuts.

Or I use a load manual or twelve, and work up slow until I get some 'common' signs like difficult extraction, obvious primer signs, or inconsistent chrono results.
SAFETY FIRST.

------------------
"All my ammo is factory ammo"

Desert Dog · February 27, 2000, 05:29 PM

When the fired cartridge case is stuck in the chamber, it is time to back off the load... or clean the oil out of the breech...: )

------------------
.45 Super... Fat and FAST...

"No provision in our Constitution ought to be dearer to man than that which protects the rights of conscience against the enterprises of the civil authority" - Thomas Jefferson

February 13, 2000, 02:42 PM	#1
Peter M. Eick Senior Member Join Date: August 3, 1999 Location: Houston, Texas Posts: 2,991	As a follow up to the post on reloading manuals, I am always curious what techniques everyone uses to determine pressure or more accurately too much pressure in handguns. I am currently using the micrometer pressure ring technique (as described in Pet Loads) and comparing the expansion of a reloaded case to a factory round in the same gun. By extrapolation if I have the same or less expansion as a factory round in my gun, I should be safe. Let me add that I also check every load with a number of modern reloading manuals to make sure that I am not violating max loads on any of them. Comments? or alternative ideas? ------------------ [This message has been edited by Peter M. Eick (edited February 13, 2000).]

February 14, 2000, 10:13 PM	#2
bfoster Senior Member Join Date: October 13, 1998 Location: N. of Fords Switch, OK, USA Posts: 297	Peter... Because of variation (both in hardness & weight) within each lot of brass and the gradual trend we have seen within the past few decades to stronger case design in the head and adjacent portion of the case I place much less faith in measuring expansion rings than I used to. I'm not saying that I believe measuring expansion rings to be entirely without merit, but I am sure that in some "hot" loads, the difference between a "safe" and "borderline" measurements is less than it used to be- that is there is less growth per unit of pressure in most lots of brass than there used to be. Assuming (as you state) that you are using current manuals, and assuming that you choose sensible data for the arm in question, I see no problem in using the published data. The "rub" comes when a new powder is introduced. It can take years for data to be published in multiple sources, and by then the powder may be obsolete. The Oehler M43 makes working up a load for new powders, or powders for which there is little data available an easy task. Bob

February 15, 2000, 10:59 AM	#3
Art Eatman Staff in Memoriam Join Date: November 13, 1998 Location: Terlingua, TX; Thomasville, GA Posts: 24,798	For pistols, I don't load maximum with fast-burning powders. I'll only load max or near-max in .357 and .44 Mags, but they are shot through a Ruger GP 100 and a Redhawk. I guess my own version of safety factor is to stay a bit below the data-books' maximum loads. I compare various books; there are occasional changes over the years as to just how Maximum is indeed Maximum. Call me lazy, I guess...Art

February 15, 2000, 06:06 PM	#4
Peter M. Eick Senior Member Join Date: August 3, 1999 Location: Houston, Texas Posts: 2,991	I tend to agree with both of you. The differences I have seen using pressure rings are not as pronounced as before (say 10 to 15 years ago). I was more curious just to see how others are dealing with the same problem. My current technique is to use the average maximum for a particular bullet weight of all of the major manuals and take that as my absolute max. I then usually start off about 90% of that and work up to 95 to 100% depending upon the accuracy and pressure ring data. About the only rounds I run full out are my 380 auto using 88 and 90 grn jhps and my 10mm in all bullet weights. I usually back the 40's and the 38 specials to at around 90%. And I run my 45's about about 100% because of accuracy. I am still learning about the 357 sig, so right now it is more like 90%. I will be curious to see what others have to say.

February 16, 2000, 04:51 PM	#5
alan Senior Member Join Date: June 7, 1999 Posts: 3,847	Peter: As you have liklely noted, a manual dating back 20 or so years, and this year's manual will not give the same loading data, likely a result of the antics of liability lawyers. Having said that, the method you described sounds as if it would make sense. Speaking personally, I have used a particular load in 45ACP for years, never measured case expansion, nor have I lost cases as a result of loosened primer pockets. This load, using Red Dot moves a 200 grain SWC bullet at 900+ f/sec, accurately. While a contemporary manual might look agast at this load, Red Dot hasn't changed in 80 or so years, the pistols certainly haven't either, so what's different? Liability Lawyers, and personal irresponsibility. Hope the above offers something to think on.

February 17, 2000, 07:56 AM	#6
skipperJ Member Join Date: October 7, 1999 Posts: 85	I rarely load at maximum, work up my loads from minimum and I check for pressure signs by looking for any flattening of the primer.

February 17, 2000, 09:13 AM	#7
bfoster Senior Member Join Date: October 13, 1998 Location: N. of Fords Switch, OK, USA Posts: 297	alan... If you have some twenty year old .45 ACP cases you might find it interesting to check internal case capacity against current brass. In general, the brass being made now has less internal volume than did older brass. Because it is designed for relatively low pressures, the change averages much less in .45 ACP than you'll find in some high pressure rifle cartridges such as the .270 Winchester. Bob

February 17, 2000, 09:28 AM	#8
bfoster Senior Member Join Date: October 13, 1998 Location: N. of Fords Switch, OK, USA Posts: 297	skipperj... While primer inspection often does show some correlation with pressure there are many conditions which can cause flattening of primers which have little to do with peak pressure. On the other hand, some primers available today will show only modest flattening at 70,000 psi. In the absence of a device such as Oehler's M43 I'd suggest measuring brass by one of several techniques described in the literature- Hornady's Loading Manual and Waters Pet Loads contain two approaches. Any time you observe primer pocket "loosening" or marks on the case head which correspond to any feature of the bolt face it is time to back off considerably. Bob

February 18, 2000, 10:39 AM	#9
skipperJ Member Join Date: October 7, 1999 Posts: 85	<P><I>Any time you observe primer pocket loosening or marks on the case head which correspond to any feature of the bolt face it is time to back off considerably. Bob </I>< O.K. Bob, So you do agree with me that primer inspection can be used to determine pressure signs? I've been reloading since 1959 and have never had a problem with pressure.

February 18, 2000, 02:35 PM	#10
jtduncan Senior Member Join Date: December 5, 1999 Location: Seattle, Washington, USA Posts: 1,686	Go to your local bookstore and just check out the "ABCs of Reloading" or the "Metallic Catridge . . ." book with a bunch of reloading equipment on the cover. all the answers are there. ------------------ *The Seattle SharpShooter*

February 18, 2000, 04:25 PM	#11
bfoster Senior Member Join Date: October 13, 1998 Location: N. of Fords Switch, OK, USA Posts: 297	skipperj... Given that (I sincerely hope) you don't want to operate in the 70,000 psi range, and given that some current primers don't show much flattening, flow around the firing pin hole, or boltface mark transfer at 70,000 psi, I'd strongly suggest that you supplement primer "reading" with other observations. Bob

February 23, 2000, 03:11 PM	#12
wildcat Member Join Date: December 20, 1999 Location: Northeast Kingdom of Vermont Posts: 88	Im surprised no one mentioned velosity.I use most of the mentioned methods but I always chronograph a new load.I figure if I am getting more velosity with my components than the load book specifies then I am also getting more pressure.With the price of chronographs under $100.00 I would not be without one.

February 25, 2000, 09:59 PM	#13
Nukem Senior Member Join Date: January 29, 2000 Posts: 709	Primers,, not reliable as a pressure sign on their own. I think many have seen some brands of primers that flatten and flow around firing pins on perfectly tame loads. Other times, when you know the load is getting up there some will never flatten. Use all the indicators you can. :-o

February 27, 2000, 11:42 AM	#14
WESHOOT2 Senior Member Join Date: February 20, 1999 Location: home on the range; Vermont (Caspian country) Posts: 14,324	I try to get the primer to blow, then back off slightly. Not safe or recommended, but I'm nuts. Or I use a load manual or twelve, and work up slow until I get some 'common' signs like difficult extraction, obvious primer signs, or inconsistent chrono results. SAFETY FIRST. ------------------ "All my ammo is factory ammo"

February 27, 2000, 05:29 PM	#15
Desert Dog Senior Member Join Date: September 22, 1999 Location: Deep East Texas Posts: 474	When the fired cartridge case is stuck in the chamber, it is time to back off the load... or clean the oil out of the breech...: ) ------------------ .45 Super... Fat and FAST... "No provision in our Constitution ought to be dearer to man than that which protects the rights of conscience against the enterprises of the civil authority" - Thomas Jefferson