Some time ago I was gifted with a significant quantity of Vihtavuori (N320 and 3N37) powders by a relative who no longer shoots (arthritis). I have been using the 3N37 for reloading 45acp for a while now. Since I use only jacketed and plated 230gr hardball bullets, load data is easy to come by, the whole process has been pretty straight forward and fun.
I recently acquired a .357 Magnum w/4 inch barrel and want to begin loading 357. Therein lays the frustration. The Vihtavuori load data available is scanty at best. I want to use either lead or plated bullets for cost savings. The problem is Vihtavuori’s reference to lead bullets. I am unable to find any reference to Intercast on-line and without that, I am unsure as to how to substitute for an available bullet. I am interested in mild to medium loads only. In 38 special, I will use the existing callout for Rainier 158gr HP. Easy peasy.
So, after that long preamble, here are my questions:
• What can I substitute (plated or lead) in .357 magnum for the callouts in the Vihtavuori load data?
• Is it possible to also use the Rainier 158gr HP for .357 mag?
• Can I substitute Berrys 158gr target HP in place of Rainier 158gr HP for 38 special?

Thanks very much for any advice or insights you all can provide me with.

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Michael O'Larte

Simple advice is to reduce posted loads by at least 10%.
Chronograph the results and work up as results indicate.
It's called load development.

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-jwk-
US Army '72-'95

What bullet are you trying to use? Simply use data for another bullet of identical weight and the same construction--i.e., using data for a Berry's 158-gr plated bullet to load for an Xtreme 158-gr plated).

You use the appropriate length for the gun in an autoloader, and load to the crimp groove in a revolver.

I think I've only had exact data for the precise bullet I was using maybe once in my life.

Alternatively, I can give you an address, and you can get all that VV powder off your hands

If you look here:

.357 Magnum - Handgun reloading - Reloading Data - Vihtavuori

you will see that Vihtavuori gives as a max load for the Intercast 160 gr. lead semiwadcutter bullet of 7.9 grs. 3N37. Keeping in mind the standard caution to start 10% low and work up, I would take that as a guideline for any 158 to 160 gr. cast bullet. Their test barrel is 7"; based on their given velocity of 1257 fps, I would guess the max load would run around 1100 from the 4" (what I would call mid-range), and a load of, say, 7.1 gr. would be a rather mild .357.

For N340 and a 158 gr. cast bullet, they quote 4.5 gr. for 804 fps; whack 3" off the barrel and you've got a target/plinking load, which they class as a Cowboy Action Shooting load.

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Pisgah

Use jacketed starting data & work up. You will rarely find exact bullet data when dealing with lead or plated bullets, so a vertain amount of extrapolation is reqd.

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NRA Cert. Inst. IDPA CSO

For a 158 grain lead bullet use the data for the 160 grain Lead Flat Nose, it's slightly heavier so start at the starting point and work up from there.

As for Plated Bullets my experience has been that Rainier, Berry's, and Extreme plated bullets are 100% interchangable if they feature the same profile. BTW, I've weighed, measured, and tested all 3 brands so this advice is based on experience using the Round Nose and Hollow Point heavy plate profiles. I'll also note that using 4 place digital micrometers all 3 brands measure within 0.0001 inch and Berry's and Extreme were EXACT matches in 357 and 45 ACP calibers.

I do not use those Vihtavuori powders, but I do use N110 and N340.

For .357 Magnum, since you're looking for mild to medium loads, I'd say start with max data for the same weight bullet in .38 Special and work up from there. I would not feel in any danger of starting with .5gr below starting .357 Magnum jacketed data of the same bullet weight.

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Authorized AMSOIL Dealer

You all are totally awesome as the surfers out here would say. Thank you for so much support and info. I have one follow up question: Can I use a bullet with the same profile to determine C.O.A.L.? An example would be using the published Speer jacketed 158gr HP COAL to set a Berrys plated 158gr HP? Seems as though that would work, but I wouldn't want to bet the farm on it.

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Michael O'Larte

If you are talking rimmed revolver cartridges that were based on black powder designs, such as .38, .357 mag, .44 Special, C.O.A.L. is not nearly as critical with modern cartridges designed for smokeless powder such as the 9mm, .40 and similar high pressure cartridges.

You can seat a bullet out as far as possible as long as the bullet doesn't bind in the forcing cone or seat it as far in as to crimp over the ogive of the bullet.

With this in mind a bullet that is similar in construction and a similar in profile that is the same weight can be considered as using the same data as long as care, common sense and good safety practices are followed.

Some more choices for inexpensive bullets are coated lead, which can be pushed as fast as jacketed bullets and some provide heavy plated bullets that could be counted as a jacketed.

In closing, I'd be pretty happy if somebody gave me a large amount of any kind of Vihtavuori powder.

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"He was kinda funny lookin'"

One observation makes loading 38 Special and every other rimmed revolver cartridge very easy.

1. Drop the loaded cartridge in the cylinder.

2. Is the nose of the bullet past the face of the cylinder?
NO = good overall length, crimp the bullet
YES = too long, seat the bullet deeper and test again.
3. If you crimp the bullet on the cannelure, your cartridge length is usually correct.

This is for rimmed REVOLVER cartridges. This does not work for rimmed rifle cartridges fired in a rifle.

(A) For load data for a specific 150 grain jacketed bullet, you can use the STARTING load data for a jacketed bullet between 145 and 160 grains safely.

(B) For a lead or plated bullet weighing 150 grains, you can use the STARTING load data for a LEAD bullet between 148 and 160 grains safely.

If you use method A or B for your starting load, make just 5 or 6 rounds and test fire that load in your gun before loading 500 rounds. Your loads will be safe, but if your want a very soft, light recoil target load, shoot the test rounds first.

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S&WHF 366

I now feel qualified to start the reloading process. I think I am really going to enjoy reloading for revolvers. My main concern with using similar bullets was establishing the seating depth so as to avoid over pressure situations, especially given that plated bullets do not seem to have cannelures as a starting point. If my understanding of this issue is correct, seating the projectile to even a small additional depth can dramatically increase the internal case pressure. By starting at the minimum load, and looking for signs of overpressure in the case/primers as I increase, I think I should be safe. Being here in Kalifornia, ranges that will allow a chrono to be set up ~15-20 feet in front of the firing line are few and far between.
The wife and I are considering evacuating to a different state for many reasons, including SA rights. Thanks to all of you fine folks for the help! I hope you don't mind if I ask more n00b questions as they arise.
Best,

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Michael O'Larte

Some notes concerning 3N37.

First, it is not the least bit Position Sensitive, even at the lightest Starting charge weight you can find listed. In a 38 Special or 357 Magnum case this is rather noteworthy, because many older powders will produce some variaiton in the produced velocity depending on how the powder charge is oriented in the case.

Second, the burn rate is quite similar to Unique so it is actually a powder with the potential for use in a large variety of calibers. Unfortunately load Data for this powder is a bit spotty so there are calibers where it may prove quite useful but isn't listed because Vihtavouri just didn't work up data for that caliber. For example you won't find any data for the 380 ACP but based on using it for the 9mm Parabellum I expect it would be a great powder for the 380.

Third positive is that it meters wonderfully, unlike Unique which meters horribly. As a result once you have your powder measure dialed in you can "throw and go" with charging cases without any concern about wildly divergent powder charges. BTW Statistically the 6 Sigma for 3N37 is +/- 0.054 grains, so 299 out of 300 thrown charges will be within this range.

The final positive is that it's a relatively low flash and clean shooting powder, even in a 2 1/2 inch model 19.

Sum it all up and the higher cost just isn't a factor worth considering. Because time saved not having to check every single charge thrown is a huge payoff if you place any value on your time. BTW, the 6 Sigma for Unique in my testing is +/- 0.51 grains, nearly 10 times the variation seen with 3N37 and a variation high enough that I would check every single charge thrown.

As in many things, it depends. .38 Special has a huge case volume, and doesn't run particularly hot. The charges used, additionally, are very small in volume in relation to the total case capacity. A hundredth or two one way or the other won't make a huge bit of difference. An experienced hand will be able to tell the difference.

Triple-charge the case, though, and a few thousandths can mean the difference between "a decidedly unpleasant experience", and "shrapnel". Wadcutters, too, are a little sensitive to this, but still--in the .38 Special, some people seat them flush with the case mouth, and others seat them into the crimp groove, and nobody has a problem.