357 Magnum 158 gr SWC & Unique

[38SPL HV]

One of my most accurate 357 Magnum loads using circa 2001 Alliant data uses a cast 158 gr SWC and 6.5 grs of Unique. Sadly, probably because of using softer lead, no current manual loads are suggested over 6.0 grs with Unique using 158 gr lead bullet in 357 Magnum.

I’ve chronographed my 6.5 grs Unique/158 gr SWC loading and it measures approximately 1,125 FPS from 6 inch GP100.

Any opinions on my load? Even Lyman’s latest cast bullet data excludes Unique and 150-168 gr loads.

 

[6string]

As a lifelong fan of Unique, I'd say your load is fine. It seems best to extrapolate as much data from different sources as possible.
Whose data is that 6.0 max load?
I find it personally a bit annoying that some manuals will leave out a classic like Unique for a bunch of weird new stuff that may or may not be available. My latest Lyman cast bullet book has nothing for 357 with Unique using bullets over 120 grs.
But, it does show 5.4 gr as a +P 38 spl load using 358156 lyman swc.
Meanwhile, 158 gr 358665 max load is 4.7 (again, 38 spl). Then, with the 160 gr 358311 goes back up to 5.3!
The lesson, in my opinion, is that there are individual factors that will affect outcome beyond printed dogma.
Unique is not temperamental. It doesn't go from safe to over pressure in half a grain. Keep an eye for any pressure signs.

The fact that your chronographed results underscores the reasonable pressure of your load is a good sign.

Jim

 

[cowboy4evr]

My personal load using Unique with a 158gr up to a 173gr swc has always been 7.0 grs in a 357 case . It is very accurate and I have never had a problem with case extraction . i will continue with this load . Regards, Paul

 

[Big Cholla]

I too like that load and bullet combo. That is a lot of velocity for a 6" barrel. Do you have any leading problems? And how is the accuracy?

 

[smoothshooter]

As a lifelong fan of Unique, I'd say your load is fine. It seems best to extrapolate as much data from different sources as possible.
Whose data is that 6.0 max load?
I find it personally a bit annoying that some manuals will leave out a classic like Unique for a bunch of weird new stuff that may or may not be available. My latest Lyman cast bullet book has nothing for 357 with Unique using bullets over 120 grs.
But, it does show 5.4 gr as a +P 38 spl load using 358156 lyman swc.
Meanwhile, 158 gr 358665 max load is 4.7 (again, 38 spl). Then, with the 160 gr 358311 goes back up to 5.3!
The lesson, in my opinion, is that there are individual factors that will affect outcome beyond printed dogma.
Unique is not temperamental. It doesn't go from safe to over pressure in half a grain. Keep an eye for any pressure signs.

The fact that your chronographed results underscores the reasonable pressure of your load is a good sign.

Softer lead does not necessarily mean more leading.
Sometimes you get a better cylinder throat and bore seal with the softer alloy.

 

[biku324]

I regularly have used exactly that powder charge and cast 155-158 grain LSWC bullets since 1975. I see no reason to change.

 

[6string]

Hi
I dug up some older Lyman manuals (1970s-80s) and have attached a couple pictures.

They have jacketed loads for bullets in the 150-160 gr range in the 6 to 8.7 gr. range for Unique. Granted, that would be older Hercules brand Unique. But, I have not noticed a significant difference in Unique regardless of the manufacturer.

With a cast bullet you could expect slightly higher velocities and slightly lower pressure than for an equivalent weight jacketed bullet using the same powder charge.
(One caveat: such substitutions and extrapolation would be very risky if we were talking about maximum loads.)

Jim

 

[dogdoc]

I think if burning rate on powders changes significantly, they (manufacturer) would change the name. Lot to lot variation can be a factor. I think the main reason for changing powder charges is improved pressure measurement equipment.


Sent from my iPad using Tapatalk

 

[rockquarry]

Unique remains a useful powder, but it's not accurately metered by some powder measures because of the coarse flake size. A number of other powders can be used to duplicate Unique's performance.

 

[cowboy4evr]

Unique has been working successfully since 1899 . Regards , Paul

 

[Warren Sear]

New or old, Unique is the same as ever, and one of the best possible powder choices for lead bullets in a .357 Magnum, or almost any handgun caliber. I have no idea why Lyman does not list data for the .357 in their newer manuals.

Pertinent to the OP's concerns, here is some data from the 45th edition of the Lyman handbook, copyright 1970:

 

[Qc Pistolero]

I don't see any problem with your load.The one I use goes a little over that and it doesn't create undue pressure in any of my .357 many of them K frames.

 

[6string]

New or old, Unique is the same as ever, and one of the best possible powder choices for lead bullets in a .357 Magnum, or almost any handgun caliber. I have no idea why Lyman does not list data for the .357 in their newer manuals.

Pertinent to the OP's concerns, here is some data from the 45th edition of the Lyman handbook, copyright 1970:

Anyone else notice how many times in Warren Sear's manual images that Unique is singled out as the accuracy load?
For those of you unfamiliar with the extent of usefulness that Unique possesses, try it for cast bullet loads in a bottleneck rifle cartridge. Assuming good bullets and loading practices, that "$1 per shot" hunting rifle becomes an affordable and accurate arm for serious target practice!
The older manuals, while not without their issues, seem to bely an age when shooters (reloaders,to be specific) took a little more time to get the most out of their effort (and relatively scarce dollars). The question of how well Unique metered never entered my head as I didn't own a powder meter, just a scale and a set of Lee powder dippers.
I wonder how many guys started out with a Lee Loader and mold (like myself!) to get their cost down to a couple cents a round?
I don't think I could have kept my hungry M29 fed for two range trips a week otherwise.
Of course, the necessary expenditure of time might make one question the wisdom of such logic.

But it sure was (is!) fun!

Jim

PS: just to tie my silly digression back to the OP, my Lee Loader .44 "go to" load was a Lyman 429348 wadcutter, using the 1.0cc Lee powder scoop for 8.7 grs of (wait for it.....) Hercules Unique!

 

[BB57]

New or old, Unique is the same as ever, and one of the best possible powder choices for lead bullets in a .357 Magnum, or almost any handgun caliber. I have no idea why Lyman does not list data for the .357 in their newer manuals.

Pertinent to the OP's concerns, here is some data from the 45th edition of the Lyman handbook, copyright 1970:

I still have every manual I've ever purchased going back to 1975 (and it was a 1973 addition).

Old manuals can have some issues.
For example, the loads in the Hornady 3rd edition are considered to be a bit hot by some due to changes in SAAMI specs in some cartridges and a move away from copper crusher to piezoelectric pressure measurement).

On the plus side however, the older manuals will still provide load data long after the folks publishing the new manuals drop the older powders to make room to publish data for the newer powders.

There's an obvious need and demand to publish new data rather than repeat what was in older manuals, but the problem is excerbated by modern marketing. Unique for example gets slammed as "flaming dirt", a reputation it gets from being the go to powder for case bullet loads in many cartridges where the lube produces far more smoke than the powder.

It also tends to leave more residue in lighter loads where it doesn't burn as clean as it does in near maximum loads. However, it doesn't accumulate and shooters looking down a barrel and noting powder residue don't seem to grasp that it doesn't accumulate and will never be more than one shot dirty.

Then of course you have the misguided souls who do stupid stuff like 2000 round tests with no cleaning - apparently thinking that going 2000 rounds without cleaning will play some sort of role in their future. You know, like kids who watched Scooby Doo cartoons and Tarzan movies thought quick sand would play a much larger role in their adult lives.

None the less, that kind of dubious and misguided wisdom drives demand for newer cleaner burning powders that more often than not, do not offer any real advantage over the old standbys.

 

[Nevada Ed]

You are a long way from my compressed load of Unique powder used
in my 686 , 6" revolver that gets 1320fps........................

Stay safe.

 

[Univibe]

Unique remains a useful powder, but it's not accurately metered by some powder measures because of the coarse flake size. A number of other powders can be used to duplicate Unique's performance.

I'd recommend AA#5 for a similar powder. Meters like water.

 

[cowboy4evr]

I don't buy current / latest load manuals . I have my loads , using older manuals that work just fine . I really don't care about the latest " whiz-bang " powders . I know what works for me and my own cast bullets . Regards, Paul

 

[Fkimble]

Lots of manuals stop short of max powder load for cast bullets, I think due to leading, real or imagined. Also depending on the shape of the bullet, powder capacity in the case will vary which will affect pressure. For the standard 158 SWC, as cast by most commercial casters, I look at the 158 jacketed version loads and consider them the truer max loadings to not exceed. But in practice, I never load lead anywhere near max.

Frank. reloading Unique since 1966

 

[BB57]

Lots of manuals stop short of max powder load for cast bullets, I think due to leading, real or imagined. Also depending on the shape of the bullet, powder capacity in the case will vary which will affect pressure. For the standard 158 SWC, as cast by most commercial casters, I look at the 158 jacketed version loads and consider them the truer max loadings to not exceed. But in practice, I never load lead anywhere near max.

Frank. reloading Unique since 1966

Agreed.

Lead hardness needs to go hand in hand with the pressure of the load and this often isn't understood.

If you use too hard an alloy in a low pressure oad, the bullet will not obturate quickly and efficiently. That will result in gas cutting as excessive gas moves past the bullet and that lead removed by the gas will be deposited in the bore.

If you use an alloy that is too soft for the pressure of the load, the soft lead won't be able to either contain the pressure and you'll get a similar gas cutting effect, or the bullet will accelerate fast enough that it will skid or out right strip in the rifling, leaving lead in the bore, and in extreme cases failing to stabilize.

It can also be very gun specific. For example, I have a 2 1/2" Model 66 that I used to develop a .38 +P 158 gr LSWCHP load with an alloy soft enough that it would expand reliably in a short 2 1/2" barrel. It shoots really well in that Model 66 and performs exactly as intended.

However, when I shot that same load in my 3" Model 686, I had keyholing bullets at 10 yards. The velocity of the two revolvers with a given load is nearly identical despite the 1/2" barrel length difference, and I suspect my 686 has a slightly larger bore than my Model 66. That reduces the 686's velocity but also reduces the soft bullet's already marginal ability to successfully engrave the rifling without stripping at the higher pressures involved when it enters the bore. The options then in my 686 are a harder alloy (that may not expand at that velocity, or a larger bullet diameter that may either achieve the required velocity with a lower pressure load, or engrave reliably due to the larger diameter, or a combination of both.

Given that published load data will get used with a vast variety of firearms using that cartridge, they have to be conservative. Cast bullets also add a host of other variables that again indicate that published data needs to be conservative.

 

[gwpercle]

RCBS Cast Bullet Manuel #1
357 magnum , RCBS #38-158-SWC , sized .358

Unique - Start load - 6.5 grs. @ 1010
Max load - 7.0 grs. @ 1089

According to RCBS 6.5 grs. of Unique is a perfectly acceptable load .
I don't see any reason to change it .
RCBS Manual #1 was published in 1986 and I refer to it often , it has never given me a bum steer . .
Gary