scary velocities with Vit 3N38

[capdek]

I recently put a new barrel with integral 5 port comp in my .38 super STI open gun and am trying some new loads. I decided to give the Vihta Vouri 3N38 powder a try. I use a 125 grain Zero FMJ bullet in a Starline .38 Supercomp case with Winchester small rifle primers and an OAL of 1.245". Based on my research, I decided to start with 8.6 grains of the 3N38, and loaded up some additional rounds with 8.8, 9.0, 9.2 and 9.4 grains of the 3N38. I went to the range with the chrono, and tested one of the 8.6 grain rounds. I couldn't believe my eyes when the chrono read 1818 fps! I wondered if this was a mistake so I tried one more 8.6 grain round and it read 1813 fps! So this was no fluke. With those kind of velocities coming out of the light loads, I figured I better pack-up and go home before I run into serious trouble!

I pulled the 8.6 grain bullets when I got home to double check the powder weights and they were exactly 8.6 grains.

I can't figure this out. Based on the Vihta Vouri specs, with a 124 grain bullet and an OAL of 1.260", 8.0 grains of the 3N38 (starting charge) should yield 1110 fps and 9.3 grains of the 3N38 (max charge) should yield 1464 fps. But I'm getting 1800 fps with 8.6 grains, a slightly heavier bullet (125 grains versus 124 grains) and a slightly shorter OAL (1.245" versus 1.260"). Does this seem possible? I'm really wondering if the powder I got was mislabeled somehow. It is clearly a Vihta Vouri standard 4 lb. jug with the usual Vihta Vouri label and it clearly identifies it as 3N38, but I'm thinking this must be a mistake. I purchased this jug from Powder Valley out of Winfield Kansas about 2 weeks ago.

This is a pretty serious issue given the incredibly high velocities I'm getting with 8.6 grains of this stuff. Does this seem possible or is it more likely this jug contains something other than 3N38?

Should I contact Vihta Vouri or Powder Valley about this?

I'm not sure what to make of this and I would appreciate any help or advice people could throw my way.

Thanks.

DEK

[jasmap]

I recently put a new barrel with integral 5 port comp in my .38 super STI open gun and am trying some new loads. I decided to give the Vihta Vouri 3N38 powder a try. I use a 125 grain Zero FMJ bullet in a Starline .38 Supercomp case with Winchester small rifle primers and an OAL of 1.245". Based on my research, I decided to start with 8.6 grains of the 3N38, and loaded up some additional rounds with 8.8, 9.0, 9.2 and 9.4 grains of the 3N38. I went to the range with the chrono, and tested one of the 8.6 grain rounds. I couldn't believe my eyes when the chrono read 1818 fps! I wondered if this was a mistake so I tried one more 8.6 grain round and it read 1813 fps! So this was no fluke. With those kind of velocities coming out of the light loads, I figured I better pack-up and go home before I run into serious trouble!

I pulled the 8.6 grain bullets when I got home to double check the powder weights and they were exactly 8.6 grains.

I can't figure this out. Based on the Vihta Vouri specs, with a 124 grain bullet and an OAL of 1.260", 8.0 grains of the 3N38 (starting charge) should yield 1110 fps and 9.3 grains of the 3N38 (max charge) should yield 1464 fps. But I'm getting 1800 fps with 8.6 grains, a slightly heavier bullet (125 grains versus 124 grains) and a slightly shorter OAL (1.245" versus 1.260"). Does this seem possible? I'm really wondering if the powder I got was mislabeled somehow. It is clearly a Vihta Vouri standard 4 lb. jug with the usual Vihta Vouri label and it clearly identifies it as 3N38, but I'm thinking this must be a mistake. I purchased this jug from Powder Valley out of Winfield Kansas about 2 weeks ago.

This is a pretty serious issue given the incredibly high velocities I'm getting with 8.6 grains of this stuff. Does this seem possible or is it more likely this jug contains something other than 3N38?

Should I contact Vihta Vouri or Powder Valley about this?

I'm not sure what to make of this and I would appreciate any help or advice people could throw my way.

Thanks.

DEK

Another option is to test some factory ammo over the chrono to make sure you're not getting a bad reading. Make sure to set the chrono up as you did for this session.

Did you notice any signs of high pressure? Did you take a look at the brass and primer pockets?

[Neomet]

Like Jason said I would doublecheck the chrono just to be sure. How did the gun feel when you shot it? 8.6 of N38 should feel pretty darn soft. A 220 plus PF shot would really get your attention.

[capdek]

Yea, I should have checked the brass for signs of high pressure, but I didn't think. I was so shocked by the results I just packed up and went home in utter disbelief!

I can say there was minimal if any muzzle flip and the recoil didn't feel all that bad, but you could sure hear the damn thing when it went off!

I have used that chrono pretty recently to test a few other loads I've worked up - 7.4 grains of Vit N350 at ~1330 fps and 6.9 grains of IMR 7625 again at ~1330 fps, and I'm pretty sure I set the chrono up the same this time as these other two times, so it seems unlikely the issue was with the chrono.

From what I'm hearing, you guys would agree that this is way out-of-line for 3N38 and my round configuration, assuming that the chrono was working properly. I guess I could try one more round just to make sure if you think it's safe to be pushing those velocity limits.

Assuming these results are indeed accurate, do you think I should contact Vihta Vouri and/or Powder Valley about this?

Thanks.

DEK

[Will Abrahams]

like others have said, i would check the brass for pressure signs. with that velocity (assuming the chrono was correct) you would have to have some major pressure signs. if not, then i would question the chrono before contacting VV.

[calishootr]

+1 to double checking your equipment, as the one post said, an 1800 fps load would really get your attention, but again, your load doesnt sound all that out of line either, I run a MG 115 hp over 8.8 of 3n37 loaded outto 1.150 and am getting last i checked in the 1400 fps range as i recall???

[G-ManBart]

I'd be willing to bet there's some sort of chrono issue going on there...no way it's giving you 1800fps. 10.0gr of 3N38 gave me 1470fps with a 115gr MJ CMJ and 9.5gr gave me 1410fps with a MG 121 IFP. I can't imagine another 400fps with a heavier bullet and a grain less of powder.

[Pezco]

I'm at 9.7 with the 3N38 with MG 121 IFP's and getting 1425 fps out of my Bedell Shorty.

Your thinking was correct to start out light and work up and then stop with the 200+ PF.

[capdek]

I am going to take a side trip to the range this morning on my way to work and check those two rounds. I'm pretty sure they'll still be where I would expect them to be. If I see super flattened primers or noticeable case bulge, that may confirm what the chrono is telling me. If not, then it is probably a setup issue with the chrono. I really do hope it's an issue with the chrono. I'll post back what I found when I get home later this evening. Thanks for the good advice everyone!

[Neomet]

N38 is to me at least a loud powder, particularly compared to N350.

[L9X25]

3N38 is one of those powders where you will often run out of case capacity before the pressures get outrageous. You were not pushing a 125 1600fps with 3N38, much less 1800 fps. Sounds like the chrono was picking up a blast wave or some other phenomenon.

[fritzthemoose]

I recently put a new barrel with integral 5 port comp in my .38 super STI open gun and am trying some new loads. I decided to give the Vihta Vouri 3N38 powder a try. I use a 125 grain Zero FMJ bullet in a Starline .38 Supercomp case with Winchester small rifle primers and an OAL of 1.245". Based on my research, I decided to start with 8.6 grains of the 3N38, and loaded up some additional rounds with 8.8, 9.0, 9.2 and 9.4 grains of the 3N38. I went to the range with the chrono, and tested one of the 8.6 grain rounds. I couldn't believe my eyes when the chrono read 1818 fps! I wondered if this was a mistake so I tried one more 8.6 grain round and it read 1813 fps! So this was no fluke. With those kind of velocities coming out of the light loads, I figured I better pack-up and go home before I run into serious trouble!

I pulled the 8.6 grain bullets when I got home to double check the powder weights and they were exactly 8.6 grains.

I can't figure this out. Based on the Vihta Vouri specs, with a 124 grain bullet and an OAL of 1.260", 8.0 grains of the 3N38 (starting charge) should yield 1110 fps and 9.3 grains of the 3N38 (max charge) should yield 1464 fps. But I'm getting 1800 fps with 8.6 grains, a slightly heavier bullet (125 grains versus 124 grains) and a slightly shorter OAL (1.245" versus 1.260"). Does this seem possible? I'm really wondering if the powder I got was mislabeled somehow. It is clearly a Vihta Vouri standard 4 lb. jug with the usual Vihta Vouri label and it clearly identifies it as 3N38, but I'm thinking this must be a mistake. I purchased this jug from Powder Valley out of Winfield Kansas about 2 weeks ago.

This is a pretty serious issue given the incredibly high velocities I'm getting with 8.6 grains of this stuff. Does this seem possible or is it more likely this jug contains something other than 3N38?

Should I contact Vihta Vouri or Powder Valley about this?

I'm not sure what to make of this and I would appreciate any help or advice people could throw my way.

Thanks.

DEK

1800 sounds a lot with this setup. How far were you away from the crono? Anyone next to you shooting?

I got 1540 out of a 9 Major with a 124 grains TFMJ with 8,6 grains of SP 2. But it was with a very low OAL meaning hard press load.

Had 1690 with the same setup and a 125 grain plastic coated Ares bullet but the Ares gives you much more fps anyway

Pressure marks clearly visible but not nearly as bad as with hotloads some years ago.

[GrumpyOne]

Maybe too close to the chrono. Back away another 5 feet and see what happens. The chrono is probably picking up the muzzle blast.

[capdek]

So I went to see if I could find those 2 pieces of brass at lunch, but hard as I tried, I couldn't locate them. :-(

It's pretty obvious the consensus here is to suspect the chrono and not a labeling issue. And I would have to think suppliers would take their product labeling process pretty seriously given the possible litigation issues that could arise if something really bad was to happen to an end user that followed their loading guidelines.

I was pretty close to the chrono - about 6 feet away - and perhaps it was picking up some of the muzzle blast as has been suggested. I will give it a try again with the chrono about 12 feet away and see if that makes a difference. I'll also make sure to catch the brass so I can check it for high pressure signs.

One thing I can say for sure, there was practically no muzzle flip and very little felt recoil with that powder. True, it was pretty darn loud, but I normally use plugs and muffs when I compete. If this does turn out to be a chrono issue, I will have found a superb load with this powder!

Thanks everyone for the help. I sure do appreciate it!

DEK

Edited September 29, 2009 by capdek

[larry cazes]

Whenever I do load development I bring a few rounds of a known load to shoot over the chrono to confirm the setup is sane. Last time I loaded my standard open load and chrono'ed some, I put aside 100 rounds as a standard. Should last a while.

[Neomet]

I think you may have hit on the issue. I think 6 feet is too close. 10 seems to be the "go no closer" line.

[jasmap]

I think you may have hit on the issue. I think 6 feet is too close. 10 seems to be the "go no closer" line.

+1 to Rick's comment. You may have found the culprit.

[norbs007]

I'll bet you that's it... too close. I use 10.1gr 3N38 over 124gr and average around 170pf.

[G-ManBart]

So I went to see if I could find those 2 pieces of brass at lunch, but hard as I tried, I couldn't locate them. :-(

I wouldn't worry about that too much. If you'd really gotten 1800fps with a 125, the case would be in pieces

I use 12-15ft from the chrono and that seems to be even more important with the slower powders like 3N38 and N105 as they tend to have more blast and throw out quit a bit more unburned powder than faster stuff like N350. R,

[Patrick82]

I also just started experimenting with 3n38 (9.4gr) with a 124gr but haven't put them the chrono yet so you almost got me worrying when I first started reading this topic

[G-ManBart]

I also just started experimenting with 3n38 (9.4gr) with a 124gr but haven't put them the chrono yet so you almost got me worrying when I first started reading this topic

Some gun/comp setups will give you pretty good sized fireballs out of the comp (often irregularly), but you'd have to work to actually hurt a Super/Supercomp using it....you probably can't get enough in the case to do any damage without really trying. R,

[SkyScrapin]

N38 is to me at least a loud powder, particularly compared to N350.

+1, I got a 3 hybrid holes and a 3 port comp w/ two bleeders. Let me tell yeah, it's important to use double protection on the ears. I was thinking about trying other powders just because of this reason.

I am using 10.6g 3n38 124 MG JHP Making major on .38sc. (I think I am compressing the charge but I haven't had any issues.)

[Patrick Sweeney]

15 feet from the muzzle is what I use, and that's far enough to preclude muzzle blast issues.

Six feet from the muzzle? 1818 fps is the average speed of the muzzle blast shock wave.

[Julien Boit]

+1 with Patrick.

http://www.youtube.com/watch?v=l5PHkv3f-9U

Check this video. The first portion shows an open gun fired in slow motion, you will see that the blast comes out of the barrel before the bullet.

[redmanfixit]

We (myself and some of my friends) have been testing ammo and found a source of erratic readings comes from illumination problems with the sky screens. So much so in fact, that in some cases putting the entire chrono in a sonnetube (big pasteboard tube for casting concrete) and supplying an artificial light source was the only way to get the chrono readings to settle down. Muzzle blast was indeed an issue but the light turned out to be very important.