Maxing out on .357 mag velocities...is this normal?

[imq707s]

In the past I've either shot cheap store bought ammo in my 4" GP100, or some low power plinking lead bullet rounds I loaded up (around 900fps).

I decided to try my hand at loading up some heavy magnum loads with W296 and 158gr hard cast coated bullets. The reloading data for H100/W296 is all over the place. I decided to use 15.0gr as my starting load, and work my way up to 16.7 (Hodgsons listed max). I even loaded up a few 17.0 and 17.2 gr loads to shoot if I didn't see any pressure signs with the 16.7.

I started off with the 15gr loads (around 1230 fps), and worked my way up. Around 16.5gr the velocities stopped climbing and stayed right around 1380fps, all the way up to the 17.2 gr loads...still around 1380-ish.

Is that normal for the velocities to stop climbing even when you are going larger on the powder charge?

[SHR970]

You just hit the wall and are getting into proof pressure territory. Yes this happens.... when your velocity gains diminish or stop you are at or passing max. pressure.

Now is a good time to back up a few steps; as in back down to book max. or even a touch below. I would consider 16.5 max for your gun.

[Fine Figure of a Man]

I ls loaded the same recently. Did not go past 16.7 but noticed diminishing returns in velocity as the charge increased. My assumption was not enough barrel to burn more powder (4 inch Ruger).

[Nick_C_S]

Yeah as SHR970 said, you're way up there and need to back off the charge weights.

If you were loading jacketed bullets, you may have ended up with a severely damaged gun (or worse). Lead makes the trip through the barrel with less pressure buildup behind it. And on the high end (where you're loading), W296 is about as forgiving as any pistol propellant. Between the two, you may have dodged a bullet - uhh, so to speak.

It's a bit of apples-n-oranges, but my max load with a 158 grain bullet (jacketed though), and W296, yields about 1275 f/s (4" bbl). Now if I were to exchange that jacketed bullet with a lead slug (which I wouldn't even consider), the velocities would be higher - so the comparison is difficult.

At those pressures/velocities, your gun's barrel must be a leaded up mess. I'd never push a lead slug that hard. But then, I don't load lead at all in 357 Magnum. My lightest range shooter loads are plated. And everything above those are jacketed. But that's just me.

[Damon555]

I've always just loaded the minimum charge weight listed in the manual for H110 and found those levels to be all I need to get the full effect of a 44 or 357. If you look at the numbers there's not much difference from the top and bottom of the H110/W296 load range as far as velocity is concerned. Try the low end.....you'll be satisfied with the results and you'll save a little powder along the way.

[imq707s]

Thanks for all the info guys. Yes, I'm going to go with 16.5grains for my loads. Good velocity, and I'm a little under max loads.

By the way....the bullets I'm shooting are powder coated, and I was told that they are good up to around 1500pfs before you run into leading issues. The barrel doesn't really look that bad after my 50 test rounds. It looks much cleaner than running 50 of my low velocity plinking rounds through it.....but those bullets are a little softer, and not coated.

[Nick_C_S]

W296 is kinda funny stuff. It doesn't like to be downloaded, and it doesn't yield higher performance when it's overloaded. It just has a sweet spot; and that's where you should run it. A bit oversimplified, but basically, that's how it behaves.

My above-mentioned 158 jacketed W296 load is in that 16.5 neighborhood you just mentioned. Probably a good spot for it.

Load safe.

[rodfac]

W296 is kinda funny stuff. It doesn't like to be downloaded, and it doesn't yield higher performance when it's overloaded. It just has a sweet spot; and that's where you should run it. A bit oversimplified, but basically, that's how it behaves....My above-mentioned 158 jacketed W296 load is in that 16.5 neighborhood you just mentioned. Probably a good spot for it.

Good info/advice there Nick CS...and I share your use of that 16.5 gr load. With a Hornady 158 gr XTP, I get a chrono'd 1225 fps in my 4" Smith M19, and my Marlin 1894 CS with its 18.5" bbl shows right at 1700 fps. Both guns are superbly accurate with it: the Smith will print 5 shots in an inch at 25 yds if I'm having a good day with my eyes and the sun's behind me, and the Marlin will do an inch and a quarter at 100 yds with a 2.5x scope mounted. It's a hellofa load for sure. I've not used it with my cast bullets, however...might have to give it a try...Rod

[44 AMP]

At those pressures/velocities, your gun's barrel must be a leaded up mess. I'd never push a lead slug that hard.

Uncoated, unplated cast lead ALLOY bullets of the correct hardness, and sized properly for your gun won't lead the bore until you get up in the 1800fps range, and with gas checks can be driven to 2200fps before leading becomes a serious issue.

HOWEVER, improper sizing (no matter what the alloy) can result in a badly leaded barrel at SUBSONIC speeds and higher. In short, its gotta be the right stuff for the speed and its gotta fit right, or it will lead the bore.

Lots of people go into loading cast bullets with their eyes wide shut, lead up a bore badly, and decide to never shoot lead again. For them, there is no help.


As for topping out at about 1380ish fps, I don't think you'll get significantly higher velocity with any powder, even if you load up to pressures where you can't extract the fired cases. A 4" barrel simply does not have the length to allow slower powders to attain their top end speeds.

To put it shortly, if you want more speed you will need a longer barrel.

And, just FYI, 16.5 is half a grain above the listed max (jacketed) in Hornady 7th edition, and their top speed from an 8" Python with that load was 1250fps.
Speer #11 (1987) lists 158 jacketed max 17.8gr with velocity of 1326fps from a 6" Ruger Security Six.

If you look at other data, you will find other results.

[shootniron]

I shoot my NOE 180gr WFN powder coated cast bullets to 1650fps in a CVA Scout without any sign of leading...that is pretty well smoking for that heavy bullet, from a handgun. This load and gun are a real hammer for a .357...and laser accurate...the most accurate of any of my single shot hunting guns. This load is using 2400...tried the 296, but the accuracy starting going away with this bullet.

So, you can certainly push that load on up there as long as the details are right. Might want to consider the reason for doing it...might not be worth it for just target shooting...hunting, is a different situation. Although, it is not really necessary for hunting, if you are gonna limit the range to 50yds.

[Nick_C_S]

I went ahead and ran the 17.2 grains through QuickLoad.

According to QL, the situation isn't a dire as I originally thought (and as 44AMP has alluded). QL predicts 38.2Kpsi - for a jacketed bullet; it would probably be a little less for a lead bullet. That's only a little over SAAMI spec; and probably within the structural integrity of the firearm. But still, it is an over-pressure and should not done.

[ShootistPRS]

The current SAAMI maximum average pressures for the 357 magnum are only 33000 psi they may be slightly over pressure but if you consider that the SAAMI pressures have been dropped first 5000 psi and then another 2000 psi, after S&W petitioned SAAMI because the loads were shaking the side covers off their smaller revolvers, you know that in a gun that can take the pressures (look at the Ruger and Contender loads) you have a considerable margin for higher loads.

If someone would like to run this through Quick Load here is a maximum load from older data:

357 magnum
Remington case
Speer 140 grain JHP
OAL 1.59"
19.6 grains of Hodgdon H-110
6" revolver

It might be interesting to see what QL says about that load.

[Nick_C_S]

The current SAAMI maximum average pressures for the 357 magnum are only 33000 psi they may be slightly over pressure but if you consider that the SAAMI pressures have been dropped first 5000 psi and then another 2000 psi

Yep. True. IMO, it's just as well. These days, I'm just fine keeping my loads to current published data; and thus presumably, 33K max. That's plenty of juice for me.

If someone would like to run this through Quick Load here is a maximum load from older data:

Sorry ShootistPRS, my QL doesn't have a 140 as a bullet choice. I could try 158 with a more shallow seating depth - but that's quite a "tweek," and would probably result in worthless data. I could try a 148 lead DEWC, but that's seriously apples-n-oranges too. Maybe other QL versions have the oddball 140gn bullet as a choice??

That's my biggest gripe about QL - crummy bullet choices. I've run into the problem of not being able to find a comparable bullet a bunch of times.

[ShootistPRS]

The Speer or Sierra 140 JHP/JHC are comparable. The older Speer 146 HP is also in the same powder capacity range. Beyond that the newest addition from Speer is a 135 grain bullet.

[Nick_C_S]

My QL only has four bullet choices for 357 - 110, 125, 148 LWC, and 158. Oh, and THREE 180 grain choices - because EVERYBODY loads bunches of 180's. It's displeasing.

[ShootistPRS]

I am surprised that there isn't a convenient way to add bullets. Programmers usually use a database or XML format to keep lists like that.

Using the current pressure levels the 140 grain load is only 18 grains of H110 so the 19.6 grain load is 8.8% increase in powder. That should be close to 100% usage of available powder volume. I load just a half grain below the max because that was where I got the best accuracy.

[SHR970]

So the issue is that Quick load doesn't have the algorythms for plated as well as powder coated bullets. BFD!

The OP hit the wall using powder coated bullets. Quick Load pressure guesses are just that guesses since the algorythms don't take that type of bullet into account.

Based on the OP's info he has hit a pressure wall. Whether or not it is just beyond or well beyond the firearms llimit is just conjecture at this point. Empirical evidence is that he hit a point that is in dangerous territory. Prudent action is to back off to where velocities are within norm and within published load levels. Without a pressure testing rig all we can do is utilize various signs of pressure levels. Flattening of velocity vis a vis load levels is one indication that you have hit the limit.

[44 AMP]

..I share your use of that 16.5 gr load. With a Hornady 158 gr XTP, I get a chrono'd 1225 fps in my 4" Smith M19, and my Marlin 1894 CS with its 18.5" bbl shows right at 1700 fps.

Longer barrel = higher velocity

Based on the OP's info he has hit a pressure wall. Whether or not it is just beyond or well beyond the firearms llimit is just conjecture at this point. Empirical evidence is that he hit a point that is in dangerous territory.

Not quite sure what you mean by "pressure wall". If you mean his velocity has peaked and increasing powder charge (which increases pressure) doesn't increase his velocity, again, I say its because his 4" barrel won't let him USE the increased pressure.

The OP does not mention any of the usual signs of high pressure (difficult extraction, flattened primers, case head expansion, etc.) so what empirical evidence are you using to determine he's in dangerous territory?

He may well be in dangerous territory, but I don't see any evidence being presented that support that, so far. All we know is that he's reached a point where he's not getting more velocity when he adds more powder.

being over SAAMI pressure limits does not automatically mean danger, it depends on the specific gun in question. SAAMI is made to be safe in EVERYTHING, and some guns will handle considerably more, in complete safety.

[TheGuyOfSouthamerica]

I wonder how much max pressure (over 35000 psi for 357 mag) these Heritage Rough Rider 357 mag SAA revolvers can stand as they are made by Pietta and should be the same as the Pietta SAA 1873 357 mag model.
In the manual I remember it said they are proofed with 3 shots each has 3 times than the max pressure/3 times the powder charge (105000 psi. Can that be??) If I recall that rigth.

As well I wonder how much over max pressure is an 38 spl case if loaded with 4.0 grains of VV N330, 148 grain LeadDEWC, 0.688“ seating depth (Nagant style deep seated rounds), velocity of 1010 fps and shot out of the SAA 357 mag revolver above.
According to QL what does the software say taking an 38 spl case (since that is what I use)?

[buck460XVR]

Maxing out on .357 mag velocities...is this normal?

Yep.....completely. Kinda why many of us have Chronos to see when we reach that point. I often wonder why so many folks are so focused on getting the most velocity outta a load instead of the most accuracy. Back before Chronos became affordable to the general public, we just pretty much loaded within tested recipes, for max accuracy. When accuracy dropped off(and it does that too) we backed off.

[Hoppy]

I decided to try my hand at loading up some heavy magnum loads with W296 and 158gr hard cast coated bullets. The reloading data for H100/W296 is all over the place. I decided to use 15.0gr as my starting load, and work my way up to 16.7 (Hodgsons listed max). I even loaded up a few 17.0 and 17.2 gr loads to shoot if I didn't see any pressure signs with the 16.7.

I bought some 296 recently and loaded up about 25 test rounds. I have yet to get them to the range. I loaded 158 grain LSWC. I powder coat with the dry tumble method. When I was looking up data it all pointed me to max at about 14.5 with lead. 16.7 is max for the XTP bullet if you go to Winchester's load data website. I cross referenced with handloads.com website and winchester listed lead max at 14.5. I think I worked up in increments to 14.3. Can't remember what the data was from my Lyman book off hand.

I'm curious how mine will do now. I have a Vaquero and SP101, as well as an 1894cs. I want a good load for all of them. I'm hoping for good results with the powder coated version. If not, I'll get a mold for a gas check bullet in the 170-180 grain range.

Thanks for posting results on your 357/296 loads

[SHR970]

The OP does not mention any of the usual signs of high pressure (difficult extraction, flattened primers, case head expansion, etc.) so what empirical evidence are you using to determine he's in dangerous territory?

Velocity flattening out IS a pressure sign. Fortunately the OP is using a forgiving powder, not something a bit more spikey like Blue Dot. Reading "pressure signs" is slightly more scientific than reading tea leaves. Where Federal SPM primers are flattening, CCI's SP are not. In many handgun cartridges, if you rely on those "classic signs" you are so far above max that you are well past proof territory.

[ShootistPRS]

When you hit a velocity plateau, what is happening is the powder is burning faster, generating a shorter but higher pressure pulse. Luckily H110 and WW 296 have a slow pressure rise and it is not instantly destructive. It is still a signal to back the load down because higher temps or letting a round sit in a hot gun can cause the pressure to jump faster.

To re-purpose and old adage:
There are bold loaders and there are old loaders but there are darn few old bold loaders.

[44 AMP]

In many handgun cartridges, if you rely on those "classic signs" you are so far above max that you are well past proof territory.

PERHAPS

And, perhaps not.

There are two things to look at here, one is the paper limits (published standards), and the other is what happens in the real world with all the different factors thrown in. The biggest of which is the specific individual gun & load.

Reading "pressure signs" is slightly more scientific than reading tea leaves.

Agree. But that "slightly" part can be a usable tool.

Not in the sense that "this sign = that pressure" in psi, cup, or whatever units you use, but usable in the sense that they show you what is going on, and not going on in your gun, with your components.

Published load data works as a guideline because the results you get with your gun and load components is generally very similar to what they tested.

But very similar is not identical, and individual guns sometimes can and do show results at both ends of the curve.

I do fully agree that when velocity flattens out, you are done with that powder and bullet combination, and the prudent thing to do is to drop back slightly below the point where velocity flattened out.

[Unclenick]

Originally Posted by ShootistPRS

The current SAAMI maximum average pressures for the 357 magnum are only 33000 psi they may be slightly over pressure but if you consider that the SAAMI pressures have been dropped first 5000 psi and then another 2000 psi, after S&W petitioned SAAMI because the loads were shaking the side covers off their smaller revolvers, you know that in a gun that can take the pressures (look at the Ruger and Contender loads) you have a considerable margin for higher loads.

Are you telling me the .357 Magnum used to be rated at 52,000 CUP, same as the .308 Winchester and .223 Remington, and a bunch of other cartridges? I don't think so. Not for the skinny edge of a revolver cylinder.

Originally Posted by Nick_C_S

Yep. True. IMO, it's just as well. These days, I'm just fine keeping my loads to current published data; and thus presumably, 33K max. That's plenty of juice for me.

This is just persistent rumor, AFAIK. The 45,000 CUP MAP is still in the SAAMI standard, unchanged from after Elmer Keith loaded to sticky extraction, reduced 5%, and the resulting loads were put through copper crusher testing.

When I noticed this claimed drop in pressures was being repeated with authority in forum posts a decade ago, I decided to go to an actual authority to inquire. I called then SAAMI technical director, Ken Greene, and asked about it. He said the illusion is created by the fact the copper crusher rating is 45,000 CUP, while the newer conformal transducer standard is 35,000 psi. The smaller magnitude of the second number makes it appear there's been a change. But he said that is a measurement artifact. That the same reference load that produces a MAP of 45,000 CUP produces a MAP of 35,000 psi in a conformal transducer barrel. We are used to the conformal transducer giving the higher reading at rifle cartridge pressures, further convincing us the pressure was changed, but that in fact the differences are inconsistent, changing both with cartridge diameter and absolute pressure. You just cannot reliably compare the two.

For example, the .223 Rem and .308 Win are both rated at 52,000 CUP. Yet when the conformal pressure transducer is used with reference loads producing a MAP of 52,000 CUP, the .223 reads just 55,000 psi, while the .308 reads 62,000 psi. The CIP channel style transducer reads a max pressure reference load as 62,366 psi for the .223, and reads the .308 as 60,191 psi. Just the opposite of the conformal transducer, the channel transducer puts the smaller cartridge pressure higher. But it's all the same pressure based on the same reference loads shared across borders. The differences are all due to limitations of the measuring systems used and, to a lesser extent, rounding error.

This is why SAAMI has a reference load system. They know that no two copper crushers or transducers will read exactly alike, even within a type. The reference load provides a calibration factor, allowing the operator to adjust for the differences on his system and wind up making cartridges to the same pressure standard anyway, even if the absolute reading on his gear doesn't match.