What pressure signs will you run into in .38 Special at 23,000 PSI?
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.38 special load question???
- Thread starter 74camaroman
- Start date
What pressure signs will you run into in .38 Special at 23,000 PSI?
None most likely. Its possible you could get flattened or flowed primers. But that can vary by brand and or lot, and primers are a poor way to judge pressure in general. I have seen one brand show no signs, another be flattened with the same load, both well under max. But if I see it I stop to evaluate.What pressure signs will you run into in .38 Special at 23,000 PSI?
Use published data, make sure your firearms are in good working order, work your loads up from start. Look for clues that things are not normal.
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What pressure signs will you run into in .38 Special at 23,000 PSI?
It's a conundrum, isn't it? The usual advice is to work up and look for pressure signs, but the max 38 special pressure limit is 17,000 psi, one of the lowest of all the calibers. Only a few are lower.
For a lot of handgun rounds the advice to "work up a load" doesn't really mean anything and will only give you a false sense of security. You could work up a load into .357 pressure ranges and you still wouldn't have any pressure signs. The gun will be taking a beating it wasn't designed for but any signs of excess battering won't show up until it's too late.
Realistically all you have to go by is the reloading data. At some point you have to use some common sense. Do you really want to run a load through your gun that is pushing a 125 grain bullet 1,230 FPS? FWIW my Lee load manual also gives 6.3 grains of N320 as the max load with a 125 grain plated bullet. So with 2 published sources does that confirm the load is safe? Or does that just mean Lee copied the VV data? Most factory 125 grain regular (non +P) ammo is running about 900 FPS. Even the majority of +P ammo is claiming slower velocity than that with most loads claiming around 1,000 to 1,100 FPS. Only the hottest premium ammo is going near 1,230.
Realistically all you have to go by is the reloading data. At some point you have to use some common sense. Do you really want to run a load through your gun that is pushing a 125 grain bullet 1,230 FPS? FWIW my Lee load manual also gives 6.3 grains of N320 as the max load with a 125 grain plated bullet. So with 2 published sources does that confirm the load is safe? Or does that just mean Lee copied the VV data? Most factory 125 grain regular (non +P) ammo is running about 900 FPS. Even the majority of +P ammo is claiming slower velocity than that with most loads claiming around 1,000 to 1,100 FPS. Only the hottest premium ammo is going near 1,230.
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Do you really want to run a load through your gun that is pushing a 125 grain bullet 1,230 FPS?
That might be the exact reason why people choose that data. They want speed.
That might be the exact reason why people choose that data. They want speed.
Definitely!
But the individual reloader must also take into consideration that a 125 grain bullet going that fast probably isn't a great choice for guns not designed to handle HOT .38 Special loads.
I know I would....Definitely!
But the individual reloader must also take into consideration that a 125 grain bullet going that fast probably isn't a great choice for guns not designed to handle HOT .38 Special loads.
Definitely!
But the individual reloader must also take into consideration that a 125 grain bullet going that fast probably isn't a great choice for guns not designed to handle HOT .38 Special loads.
Well … show me a 38 revolver that’s been shot loose by hot 38 special. Or even +p 38 when it’s not rated for it.
I’ve never seen one. I’ve handled and owned some of the most beat up model 36s, old charter arms, Spanish revolvers, etc. I’ve never seen one that’s been shot loose by hot 38s. It’s just not a thing. I suppose with a iron (not steel) revolver manufactured from 1899 to 1915 you might see one. But any 38 made in the last 70 years just doesn’t shoot loose. Sure they may be junk and have other mechanical issues, but shooting loose isn’t one of them.
That said, Uncle Nick has good advice. Stick to published load data. You generally won’t see any pressure signs at all in an over pressure 38 round until you are very far past the rates pressures.
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Pressure discrepancy solved by a bit of research
Pressure difference explained. The Vihtavuori (VV) loads are above SAAMI +P limits, as QuickLOAD and GRT said they were and got very close to. In U.S. ammunition market terms, they are +P+ loads. Here’s what I found:
First, in post #7, I said the CIP MAP for 38 Special was 17,400 psi (1200 bar). (Note that I am rounding the psi conversions to the nearest 100 psi.) This turns out to be correct for wadcutters only. Unlike SAAMI which rates both the regular 38 Special and 38 Special Match (wadcutters) at 17,000 psi and 17,000 CUP Maximum Average {peak} Pressure (MAP), the CIP separately rates the regular 38 Special at 21800 psi (1500 bar) and 23,200 CUP¹ (1600 bar). When I saw the wadcutter pressure (page 4 of the handgun cartridge homologation table) I just assumed it would be the same for the regular load just as it is in SAAMI tables. Yet another lesson in how to spell “assume”. It turns out I needed to go back one page to page 3 of the tables to see it was different for the CIP.
Why is it different? My guess is this is the result of the difference in SAAMI and CIP proof load requirements. SAAMI requires cartridges in the range of 15,000 to 18,000 psi to have a minimum proof load that is 135% of service pressure, while the CIP requires proof at only 125% of service pressure. If you take the minimum SAAMI +P proof load of 27,000 and divide it by 1.25, you get 21,600 psi, just 200 psi short of the 21,800 psi the CIP actually uses for its MAP number. CIP pressures for handgun cartridges are rounded to the nearest 50 bar (726 psi) in this pressure range, so bar unit rounding accounts for the 200 psi difference.
It would be easy to assume the above pressure differences are just instrumentation artifacts, but in this case, they are not. My copy of the 1995 second edition of the Vihtavuori manual shows both the U.S. and CIP pressure standards for 38 Special. It then has two separate load tables, one to meet the CIP standard pressures and one to meet the U.S. standard. So, for example, a 124-grain lead bullet in that manual has a maximum charge of 5.4 grains of N320 in its CIP standard tables, while on their table for SAAMI limits, the same bullet maximum is 4.8 grains. For the 125-grain Hornady XTP, they have 5.9 grains as the maximum in the European table, and 5.2 grains as the maximum for SAAMI specs.
In the current VV online data, the XTP maximum has been lowered to 5.6 grains for N320. The COL is the same. I don’t believe Hornady has changed the length of the bullet, but that can be checked. It is probably just reflecting better measurements arising from the switch from the copper crusher standard (the earlier loads) to the transducer standard. The 124-grain lead bullet data and the Ranier plated bullet data available in the 2011 manual have been eliminated in the online data (Ranier folded up shop and the Berry’s data has been put in its place). The Ranier data matched the lead data in the older manuals, but the Berry’s is higher, perhaps due to bullet seating depth differences.
The bottom line is, the loads shown in current VV data all reflect the CIP standard pressure, while the SAAMI pressure level load lists have all been dropped. This will prove to be no real issue for modern 38 Special guns, as SAAMI has changed the proof load pressure from separate pairs of values to having all guns chambered in 38 Special meet +P proof levels, which are 27,000 to 29,500 psi.
For some of the older lightweight guns with aluminum frames, though, this could be an issue. Reports of aluminum frame stretching in the S&W Airweights have been around for a long time, and, IIRC, originated with Air Force, as I believe they these guns as pilot sidearms. In this article, Masaad Ayoob describes having to have his Airweight rebuilt because of it:
So that's two boxes, or 40 to 100 rounds, depending upon whose +P+ ammo it was, succeeding at stretching the frame. Since those days, scandium-aluminum alloy, which is much stronger, has been used in many lightweight frames and I would not expect these to exhibit that problem, and, indeed, those guns are typically rated for +P.
As to pressure signs, in addition to frame stretch, which you can detect with feeler gauges between the recoil shield and the back of the cylinder, the other important one for revolvers is the classic sticky case ejection pressure sign, the one Elmer Keith and his cohorts used to develop heavy loads in their day. This sign depends on the fact steel has a greater elastic range than brass does (one reason it makes better springs) and about 10 times brass’s yield strength (the other reason it makes better springs). As pressure grows, it stretches the chamber walls and the brass that is expanded against those walls on the inside. With enough pressure, brass expands past its elastic limit (its yield point, beyond which it can no longer spring back to its original shape) before the steel does. Then when the pressure drops and the steel returns to shape. it does so over top of brass that can't. The brass is then too big for the chamber and will be trapped by the steel, which is squeezing it. This makes it hard to extract. It's a little like having a case in a sizing die without lube. It also means you are getting too close to the limits of the steel’s strength for comfort. If you encounter such a sign in a revolver during your load workup, the general rule of thumb is to knock your load down at least 5%.
¹ Note that I inserted CUP here. The CIP never did. It just used bar by copper crusher in the past and uses bar by piezo transducer today. Today, copper crusher standards are obsolete under the CIP. Unlike SAAMI, which publishes both standards.
Pressure difference explained. The Vihtavuori (VV) loads are above SAAMI +P limits, as QuickLOAD and GRT said they were and got very close to. In U.S. ammunition market terms, they are +P+ loads. Here’s what I found:
First, in post #7, I said the CIP MAP for 38 Special was 17,400 psi (1200 bar). (Note that I am rounding the psi conversions to the nearest 100 psi.) This turns out to be correct for wadcutters only. Unlike SAAMI which rates both the regular 38 Special and 38 Special Match (wadcutters) at 17,000 psi and 17,000 CUP Maximum Average {peak} Pressure (MAP), the CIP separately rates the regular 38 Special at 21800 psi (1500 bar) and 23,200 CUP¹ (1600 bar). When I saw the wadcutter pressure (page 4 of the handgun cartridge homologation table) I just assumed it would be the same for the regular load just as it is in SAAMI tables. Yet another lesson in how to spell “assume”. It turns out I needed to go back one page to page 3 of the tables to see it was different for the CIP.
Why is it different? My guess is this is the result of the difference in SAAMI and CIP proof load requirements. SAAMI requires cartridges in the range of 15,000 to 18,000 psi to have a minimum proof load that is 135% of service pressure, while the CIP requires proof at only 125% of service pressure. If you take the minimum SAAMI +P proof load of 27,000 and divide it by 1.25, you get 21,600 psi, just 200 psi short of the 21,800 psi the CIP actually uses for its MAP number. CIP pressures for handgun cartridges are rounded to the nearest 50 bar (726 psi) in this pressure range, so bar unit rounding accounts for the 200 psi difference.
It would be easy to assume the above pressure differences are just instrumentation artifacts, but in this case, they are not. My copy of the 1995 second edition of the Vihtavuori manual shows both the U.S. and CIP pressure standards for 38 Special. It then has two separate load tables, one to meet the CIP standard pressures and one to meet the U.S. standard. So, for example, a 124-grain lead bullet in that manual has a maximum charge of 5.4 grains of N320 in its CIP standard tables, while on their table for SAAMI limits, the same bullet maximum is 4.8 grains. For the 125-grain Hornady XTP, they have 5.9 grains as the maximum in the European table, and 5.2 grains as the maximum for SAAMI specs.
In the current VV online data, the XTP maximum has been lowered to 5.6 grains for N320. The COL is the same. I don’t believe Hornady has changed the length of the bullet, but that can be checked. It is probably just reflecting better measurements arising from the switch from the copper crusher standard (the earlier loads) to the transducer standard. The 124-grain lead bullet data and the Ranier plated bullet data available in the 2011 manual have been eliminated in the online data (Ranier folded up shop and the Berry’s data has been put in its place). The Ranier data matched the lead data in the older manuals, but the Berry’s is higher, perhaps due to bullet seating depth differences.
The bottom line is, the loads shown in current VV data all reflect the CIP standard pressure, while the SAAMI pressure level load lists have all been dropped. This will prove to be no real issue for modern 38 Special guns, as SAAMI has changed the proof load pressure from separate pairs of values to having all guns chambered in 38 Special meet +P proof levels, which are 27,000 to 29,500 psi.
For some of the older lightweight guns with aluminum frames, though, this could be an issue. Reports of aluminum frame stretching in the S&W Airweights have been around for a long time, and, IIRC, originated with Air Force, as I believe they these guns as pilot sidearms. In this article, Masaad Ayoob describes having to have his Airweight rebuilt because of it:
"I’ve had a Model 38 Bodyguard Airweight from the 1970s rebuilt at least twice, once as a direct result of two boxes of Federal .38 Special +P+ ammo that stretched the aluminum frame’s cylinder window to the point where excessive headspace was causing misfires."
So that's two boxes, or 40 to 100 rounds, depending upon whose +P+ ammo it was, succeeding at stretching the frame. Since those days, scandium-aluminum alloy, which is much stronger, has been used in many lightweight frames and I would not expect these to exhibit that problem, and, indeed, those guns are typically rated for +P.
As to pressure signs, in addition to frame stretch, which you can detect with feeler gauges between the recoil shield and the back of the cylinder, the other important one for revolvers is the classic sticky case ejection pressure sign, the one Elmer Keith and his cohorts used to develop heavy loads in their day. This sign depends on the fact steel has a greater elastic range than brass does (one reason it makes better springs) and about 10 times brass’s yield strength (the other reason it makes better springs). As pressure grows, it stretches the chamber walls and the brass that is expanded against those walls on the inside. With enough pressure, brass expands past its elastic limit (its yield point, beyond which it can no longer spring back to its original shape) before the steel does. Then when the pressure drops and the steel returns to shape. it does so over top of brass that can't. The brass is then too big for the chamber and will be trapped by the steel, which is squeezing it. This makes it hard to extract. It's a little like having a case in a sizing die without lube. It also means you are getting too close to the limits of the steel’s strength for comfort. If you encounter such a sign in a revolver during your load workup, the general rule of thumb is to knock your load down at least 5%.
¹ Note that I inserted CUP here. The CIP never did. It just used bar by copper crusher in the past and uses bar by piezo transducer today. Today, copper crusher standards are obsolete under the CIP. Unlike SAAMI, which publishes both standards.
74camaroman
New member
REDDOG-- The snubies I have are a Charter Arms .38 5 shot, a S&W 642-2 Airweight, .38 +P Hammerless. I think I am OK with the S&W but not sure about the Charter arms in .38 special.
jetinteriorguy
New member
A wadcutters case is designed for shooting 148gr wadcutters seated flush with the case mouth. The thickness of the brass stays the same all the way down to the cannelure on the brass and doesn’t start tapering in thickness until past that point. This way it won’t swage the diameter of the bullet since wadcutters are pretty soft. Because of this the bullets diameter stays tight in the bore preventing any gas cutting and keeping any barrel leading to a minimum, if not eliminating leading entirely. All of this helps with the accuracy a wadcutters is known for and why they used to be so common for bullseye matches. If you ever get the chance to shoot a nice S&W model 14 with WC’s you’ll see what I mean.