Discrepancy in reload data: powder vs bullet

[Autumn]

I'm a new reloader, taking it slow at every step.

I bought some 180 gr, 40 S&W Speer GDHP, and I have the Speer reloading manual.

When my powder arrived (VV 3N37) it also had reload data. However, the ranges of safe powder amounts don't even overlap.

So I wanted to check methodology: load the smallest amount from the source that has the lower range, fire 10 or so rounds, then move up a tiny bit until I'm either happy with the load, or I see signs of pressure (which means I should go back a bit).

If that is correct, what are the most indicative signs of pressure I'm likely to be seeing?

Thanks.

[Nick_C_S]

Welcome to TFL.

Whenever I need load data, I first reach for my Speer #14. And considering we're talking an actual Speer bullet, I would likely look no further. So if I were in your position, I would load to the Speer data and would have never known about the conflicting information - nor would the resulting ammunition

As for pressure signs, I don't shoot 40 S&W (I do 10mm), so I'm reluctant to give specifics. For me, with most semi-auto's, recoil will start to feel sharp and "just not right." Hard to explain; I've been shooting for over 30 years. If you stick with the Speer data, and load with diligence, it's unlikely you'll run into a pressure problem. Start by loading just a few rounds, and go from there.

[mehavey]

I looked and you are correct -- not even any overlap (passing strange).

180gr Speer/VV-3N37:
Vihtav Source 5.9 -6.2
Speer Source 6.6 - 7.2

Looking around I see folks citing starting/operating loads of 6.1 - 6.8 for their guns.
That's a fair entry point. And unless you have a chronograph, not a bad range.

Min load is the one that will function the slide reliably.

[Nick_C_S]

Hmm, I just looked at the 10mm data for the same, and it's even more out of range:

Vihtavuori: 6.1gn to 7.2gn
Speer: 9.0gn to 10.0gn

I've seen conflicting load data before, but these may be the biggest. I agree that knowing this, it would make me a little nervy using the Speer data. But in 30 years, my Speer manual has never failed me.

[serf 'rett]

I have found Speer load data to be on the high end compared to other data in 9mm and 40S&W. I tend to start with the lower end of published data and work up a series. Pay close attention to all of the details, such as overall length in 40S&W.

[Autumn]

Thanks everyone.

It was really odd. Especially since the VV data indicates a COAL 0.006" longer, which (in my limited understanding) should reduce pressure even further. If it had been the other way around (longer COAL with the greater powder amount) I might have thought it made sense.

[Nick_C_S]

a COAL 0.006" longer, which (in my limited understanding) should reduce pressure even further.

Yes, it does generally. But I think it's important for the novice loader to understand this phenomenon in a little more detail. A more accurate description is to say that the more internal case volume, the slower the burn rate. The slower burn rate flattens the pressure curve; which means the peak pressure is usually a little lower.

That's why cavernous cases - like 38 Special - lend themselves to faster powders. For instance, in 38 Special, a fast powder like W231 would have a pressure curve similar to an intermediate burn rate powder like HS-6 in the much smaller 9mm case.

[rg1]

I agree that Speer's maximum charges for Gold Dots is higher than I want to go in 9MM and 40 S&W but their start charges have been safe. Good idea to compare and work up.

[hartcreek]

I find errors in reloading manuals but then I have the experience to see the errors. New reloaders do not. You need more then one manual so purchase some more.

[PA-Joe]

As a general rule bullet makers show higher charges and velocities so that their bullets look better. Powder makers show lower charges so that they don't get blamed when something goes wrong.

[John0011]

I am loading 180gn nosler hollow points with 6gns of vv 3n37.
The pistol cycles just fine, but it sounds like from this conversation I could go a little higher on the powder charge, say 6.2gns.
I am looking into a chronograph to see what is really happening.
Anny one ever chronograph this combo?

[stubbicatt]

Perhaps I am the only one who has experienced this phenomenon. Perhaps I am just unlucky. But I thought I'd share, as it might save you a similar excursion.

As I'm sure you know, some 40 S&W's have a "tapered chamber" or "unsupported" chamber. Glocks being notorious for this condition. Due to this feature, which as I understand it, allows the rounds to feed reliably, the brass swells upon firing to conform to the chamber. You get "guppied" or bulged brass as a result.

It is my opinion that as a result, the brass will wear out more quickly, and it may become unsafe.

Also, as I have read elsewhere, some early cartridges for this number were manufactured with pretty thin case webs, for whatever reasons. PMC among them.

Using otherwise safe data, which I had shot countless times before in the same pistol, I had a cartridge rupture at the case head. I was shooting a Smith and Wesson pistol that was a Walther type, plastic framed pistol. I think they called it a P99. The escaping gas ejected the magazine, and broke the frame, and burst through at a couple of points. I am lucky I suppose, that I suffered nothing more than a cut on my trigger finger near the first knuckle. The scar is still there as a reminder, I suppose.

I'm not sure what to make of the data I take away from this experience. I'm not so arrogant to rule out an overcharge, or maybe even bullet setback caused the problem. For several reasons I do not think an overcharge was the cause. The cause could be the thin web PMC brass. I'm not sure that there is anything that can be done to correct this problem other than to be sure yours is a fully supported chamber. For myself, I decided not to shoot 40 S&W anymore. My reasoning is if the brass has been weakened by "guppying" it may not be safe to use, and I am unaware of any method to determine whether this has happened to the brass, other than to start with brand new cartridges, in a fully supported chambered gun, and only pick up those you know are your own. Some guys roll their brass, or force it through a die to remove this deformation. For myself, I am unconvinced that even if these methods are used, that the resulting correctly formed brass will not still be weakened by an excursion through a Glock-like or Smith and Wesson-like chamber.

I accept that others may disagree with this decision, which is fine, but the data speaks for itself. I guess if you continue to shoot one of these pistols it would be prudent to reload the brass at the lowest powder charge weight.







I now believe that there are varying degrees of "safe" when one speaks of load data, and having had this experience, I truly respect that safety in our hobby ultimately rests on the practitioner. Your decisions are your own, and you alone reap the benefits or suffer the consequences of any decision you make re: powder charge weights, chamber design, seating depth, or brass chosen -- in short, the quality and dimensions of your cartridges.

40 S&W is a high pressure cartridge, notoriously finicky about seating depth and charge weights. There is little margin for error with this cartridge.

One of the lessons I learned from this experience is to not approach maximum powder charge weights in my hand loads, or do so with extreme caution. Another lesson is to be certain that your firearm has a fully supported chamber. Another is to be sure of the origin and condition of your brass, as at this point in my life I purchase new brass for my hand loading, no longer picking up range brass, or purchasing "once fired" brass off the internet. Yet another lesson is that while perhaps one will not achieve the velocities otherwise attainable, typically one can find an accurate load at less than maximum pressures, and by my way of seeing things, by keeping pressures lower, perhaps avoid a repeat of an unpleasant experience.

There are surely other lessons, and I leave it up to you to determine whether any of this is helpful to you.

[mehavey]

Ouch !

Glad you're all right Stubbie... and kept all your fingers/typing ability/sense of humor.

[griz]

Vihtavuori: 6.1gn to 7.2gn
Speer: 9.0gn to 10.0gn

Wow, that's more difference than I have seen before. If I had to use that powder, I would first look for a third source of data. If none were available, I would start at the lowest end and go from there. I'd probably load only one round and chrono that. If I didn't have a chrono I would go by recoil and how well it cycled the action. (A pretty reliable indicator of "normal") Then I would work up to a comfortable load that worked.

[Autumn]

I have a chrono. How would I use it in reloading? I've never used it for anything other than ballistics for rifle.

[mehavey]

When reloading, a chronograph gives you first look at whether the cartridge is performing anywhere
close to what the manual predicts for a bullet/powder/barrel combination.

Your (your) case, a starting load of, say, 6.1gr of 3N37 under a 180 bullet should be going out ~1,000fps.
If it's way off (significantly lower) from that in a 5½" barrel, then you know the Vihtavouri data is way
off (low), and Speer is right (maybe ).

[buck460XVR]

If I had to use that powder, I would first look for a third source of data.

This is why I always use at least three published sources as reference when developing new loads(Lyman shows 6.1-6.8 with a 180 jacketed in .40 S&W). With three or more sources you can see a pattern or see readily if one of the sources is extremely low or high.

[FITASC]

I would go with the folks responsible for making the boom - the powder maker. Published data in books can be outdated by the time the book hits the shelf. The powder maker is the one assuming a lot of liability.

Then there is always calling Speer and talking to a live person.......

[44 AMP]

Don't overlook the simple fact that everyone publishing data, is doing their testing in different guns.

And what is safe, and a good working load in one gun can be a poor working load, or even unsafe in a different gun.

Our industry standards are made to be safe in ALL guns.

That's why the data is not identical.

[mehavey]

Originally Posted by 44 AMP

everyone publishing data, is doing their testing in different guns

Agree, BUT.....

The Speer vs Vihtavouri data on the 40 S&W/180gr/3N37 was so completely out of whack as to be a major potential blunder.

(That's where a chronograph comes into its own)

[FITASC]

That's where a phone call comes first before shooting over the chrono; if you load the wrong load first, it might not matter what the chrono says........

[mehavey]

a phone call comes first...

That's why you go LOW first.

(I wouldn't have any problem
w/ the VV 6.1gr start point for
calibration)

[buck460XVR]

That's where a phone call comes first

That's why you go LOW first.

....or again, simply refer to a third published source. Over the years I have come across the same scenario as the OP on different occasions. Start loads from one source higher than the max loads from another source. Both considered safe loads in any modern firearm, neither was a printing error or a mistake. In every case, the third source was somewhere in between the extremes and had some overlap.

[mehavey]

See Post #3

[Clark]

CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

In 40sw 200 gr 3N37:

a) Vihtavuori web site: 6 gr. 1.126" , 988 fps

b) top of my work up, all I can fit in my gun: 9 gr 1.158", 42% extra powder.. still a wimpy load, but low flash