I found a pound of Vv 3N37 today and thought it would be great for 38+p Spl loads.
But, I can only find 38 spl data and not even pressures (PSI/CUP)

Anybody know where that info would be hiding?

Some people have made reference to a hard manual but the latest I found was 2002, yet out of stock everywhere i looked. And im not sure if it even has this info

This is really for single-base nitro-cellulose powders, but at handgun pressure levels works out close enough for all.

+P pressure is ca. 10% higher than standard pressure. Velocities increase in direct proportion to charge weight, within reasonable ranges. Pressure increases at approximately twice the charge weight increase. So, to get a reasonable +P load simply multiply the maximum standard load by 1.05. Example: Standard load = 10.0 gr x 1.05 = 10.5 for +P load. Or if you are trying to duplicate a specific velocity increase the charge until you get the desired velocity. Just do not exceed the 105% of the standard load. This best if you have verified chronograph data for the load you are trying to duplicate, and not trying to match factory published data. Real guns rarely will give the published velocity by the factory! Often (usually) even a +P load will not give the published velocity for the standard pressure load.

NOTE: ALWAYS work up to maximum charges, whether published or derived. And, in most cases, the only "pressure sign" you will ever see in any handgun is catastrophic failure of the firearm! This is why every hand-loader needs a chronograph!

I think that if you use the maximum charge listed for 38 spl in the Vihtavuori reloading guide you will find that what you are really getting is a +P load. If you are getting a 158 grain bullet to go 1000 FPS or more I suspect you are in +P territory.

Yeah, I was thinking the same thing. If I can get it to match or exceed my results with Power Pistol under the 135 GDHP (without the flash and boom) using the VV's 38 SPL max data, I will stop there.

But if I don't, it will be guesswork as to the pressures im getting by trying to work up from that. Hard to believe it would be so hard to find the std pressure for their 38 loads.


Alk, Thanks, good to know.
I'll keep the x1.05 in mind and not exceed this.

I have a hard copy of their second edition hard manual, 1995. They obviously generate their data on a computer since all their pressures are exactly the same.

The hard copy differentiates between data for the CIP and SAAMI. Max loads for the CIP are 23200 psi while SAAMI's is 17,000 psi. Their actual data for the CIP max loads is about 22481 psi, while SAAMI is 16200 psi

Looking at a copy of their loading guide no. 6, the max data listed in it is actually much closer to the CIP data in the reloading manual.

One thing to remember is that the velocities listed in the Vihtavouri data can only be obtained if you shoot them in a rifle. Huh, what am I talking about? I'm talking about Manufacturer HYPE, something I've found nearly universal with the exception of Speer. In the case of Vihtavouri they claim to have used a 10 inch long barrel for the 38 special data but their velocity results are so high that it must be one smoking fast 10 inch barrel for this caliber.

As an example VV lists a 6.7 grain load as producing an interpolated (average of max and min) velocity of 1105 fps. with a 125 grain plated bullet. I've actually tested this particular load using a Rainier plated bullet and out of a 6 inch Dan Wesson the produced velocity was only 800 fps. I also tested the load out of a 20 inch 1892 Winchester Rifle and the produced velocity was 1150 fps.

Now, the good news is that 3N37 is an excellent powder for the 38 special, which is why I have about lbs. of it and am looking for more. However I only expect to duplicate the published velocities in one of my 357 Magnum Rifles. As for your desire to load to +P levels, 3N37 is slow enough to be a good choice for 357 Magnum Handgun loads so at a +P load level I would not expect it to be excessively Flashy or Boomy. In fact it should work quite well, just don't expect to get the velocities listed by Vihtavouri for this powder from any real world handgun.

PS; out of my 6 inch Dan Wesson or Reflex sight equipped 620 that 6.7 grain load of 3N37 is darned near a tack driver, in single action shooting offhand sub 1 inch groups at 50 feet are predictable.

Thanks Scooter,
that's very good info. I actualy loaded some 125 Berry plated over 7.0 grs 3N37 and was concerned from the data that I would be pushing them too fast in a 6".

I have more at 6.gr under a hornady 158 swaged I'm goanna try today and hoping I don't get leading.

Just cracked the jug open, and eager to see if it was worth the premium price.

BTW- their site's load data for 38 spl says its 6.5" barrel, maybe they updated their velocities on the latest data, but, like you, I think their results may still be unrealistic.

Shooter, the velocity difference could very well be the difference between shooting through a non-vented barrel (rifle or test barrel) versus a vented barrel (revolver). I recently got a chronograph and went to the range with 3 different 357 Mag pistols. 2 of them were Model 27s with different barrel lengths and the third was a Coonan Classic, which is a semi-auto 1911 style 357 Mag. The revolvers had a 5" and a 6 1/2" barrel and the Coonan has a 5" barrel, but since a semi-auto measures everything including chamber as the barrel length, the effective barrel length of the rifled part of it is only around 3 1/2". Shooting all 3 pistols over the chrono showed that the Coonan matched or exceeded the velocities of the 2 revolvers with 4 different loadings. 3 of the loadings were my handloads and the fourth was some PMC Bronze factory stuff, all with 158 grain jacketed soft point bullets. So if the companies are using a single shot test barrel type setup for their velocities instead of a production pistol, the velocities they show could be quite a bit higher than what we see with our revolvers.

Speer #13 and #14 have +P data for this powder. loaddata.com also has some loads. The ones I looked at were not very impressive.

Range report with max 38 spl Vv data x1.05
38+p (Win cases)
4 inch S&W 686
Lee FCD medium crimp
Primer: Rem 1-1/2 SP

135 gr Speer GDHP
avg 1074
ES 28
SD 14
2.5" grp @25yd

158 gr LSWCHP RimRock Gas check
Avg 1054
ES 13
SD 6
4" GRP @25YD

At first these look pretty good, however, when I shot the 135 GDHP with my PowerPistol load it was the same velocity with a smaller spread. Yet the 3n37 accuracy was a little better.

My HS6 load with158g RimRocks avg only 963 but much more accurate.

So nothing extraordinary, just different. I did notice some unburnt powder with the 3N37 though. Im sure I was at +p charges so maybe a heavier crimp is needed.

Speer #13 +p loads

3n37 110 gr HP-Start 6.9 max 7.3

3n37 125 gr HP-Start 6.9 max 7.2

Hope this helps-I really like 3n37 for full power loads in 9mm loads as well.

Thanks George, but VV's website data for 125 xtp at standard 38 SPL shows start 6.8 and max 7.5 gr. ?

And 110 gr is 7.3 to 8.2
why would +p data be less?
Something is a miss here.