Going below the data sheet on 3N38 question

[frgood]

I just tried a few rounds of VV 3N38 with 165 FP per Vihtavouri's guide of 9.6 - 9.8 grains, OAL - 1.126. The data load produces +1250 fps and a pretty good fireball.


I understand this means a lot of un-burned powder. Here is my question. What are the concerns with going under spec? And I mean in reference to this formulation. For Major PF I only need to keep above 1000 fps. Should I roll about 5 rounds each of decreasing powder amounts? If so by what value? Would .5 gr.s be reasonable until I get a clean burn and good velocity.


What is squib potential when going significantly below the minimum?

FYI, I am testing this powder in hopes of powder cost by using only one powder. I use 3N38 for my 9mm and currently am using N320 for .40. If I could use reliably 3N38 for all my calibers I could justify just buying high lbs. of 3N38. Instead of buying two different types.

 

[Walkalong]

If you are going to limit yourself to only one pistol powder, you need to pick one that is more versatile.

 

[frgood]

What powder more versatile for 9MM Major and 40 SW Major Power factor?

 

[Sunray]

"...concerns with going under spec?..." You mean under minimum? That can be as dangerous as going over max. It can cause the powder to detonate vs burn and create weird pressures that can blow your firearm. Isn't something that happens often though. That squib will give you enough grief. Moreso if you don't catch the light shot and fire another round after it. Means a new barrel at least.
"...could justify just buying high lbs...." Work up the load before even thinking about buying in bulk.
"...powder more versatile for..." Net search "9mm major load data".

 

[ATLDave]

Are you trying to make major in 9mm? I presume this is for some kind of race gun with a compensator, no? If so, don't you want large volumes of gas?

Is the .40 major for a non-compensated gun? If so, you'll probably want something different.

HOWEVER, I have heard some people say that they can make major with AA#7 (well past SAAMI, but that's just about required for 9mm major), which does run comps reasonably well. And I've shot a lot of .40/10mm major with AA#7, though it is pretty flashy in that application.

HS6 might be feasible... don't know if you can get it to major in 9mm, though it looks as though at least some people online say they do so.

But, really, I think the idea of becoming reliant on one powder (which will necessarily be suboptimal) for 2 different applications is not smart. Think about the recent powder shortage. Shooters who had learned to use multiple powders were certainly better able to either shift their shooting habits or their loads to use different powders. Becoming wholly dependent on one powder means trouble if the supply goes way down or prices go way up.

 

[frgood]

After doing a little more than a net search. I find that N320 is almost good for 40 SW Major. It is borderline 1000 FPS. So, as I continue through the Vihtavouri Load Data book, I find N340 produces a nice safe range of 1100 FPS for 147 gr. FP 30 SW.

In the same load data manual (Vihtavouri), we find one of the only listings for 9mm Major. 147 HP 1200 FPS using 3N38.

In the same load data manual (Vihtavouri), we find listings for .40 S&W Major. 165 FMJ 1211-1252 FPS using 3N38. This guidance produces far too much noise and a pretty large fireball. This is far too distracting for competition.

I have abandoned my previous question and return to the 3N38 for 9mm Major. It works well in my open, comped gun.

I will test N340 for the .40 as the N320 is a tad slow.

All values are within published data. All formulations produce desirable results.

My goal is to crank some ammo and keep on practicing (and still be able to make rent ).

Thanks to everyone for their guidance it is very helpful.

 

[ATLDave]

I know a lot of guys who love N320 for .40 major... under a 180 grain pill. While this is somewhat subjective and varies by person, the conventional wisdom/majority view is that, in a NON-COMPENSATED gun, a relatively heavy bullet and fast-ish powder produces less perceived recoil than a lighter bullet and/or slower powder.

 

[ljnowell]

"...concerns with going under spec?..." You mean under minimum? That can be as dangerous as going over max. It can cause the powder to detonate vs burn and create weird pressures that can blow your firearm. Isn't something that happens often though. That squib will give you enough grief. Moreso if you don't catch the light shot and fire another round after it. Means a new barrel at least.

"...could justify just buying high lbs...." Work up the load before even thinking about buying in bulk.

"...powder more versatile for..." Net search "9mm major load data".

No, it won't cause a detonation. It's something that can't be proven or duplicated in a lab with large rifle cases and an even greater myth in handgun cartridges.

 

[frgood]

I will make a test batch of 180's for the N320. It seems that 916 fps is right in the sweet spot. It may find a more reliable batch than the 165's that hover at the line of 1000 fps

 

[Mad Chemist]

3N38 performed poorly for me when reduced in 9x19. I would expect the same results in .40 since operating pressures are similar between the two calibers.