Why the conflicting data?

[Sixer]

I recently started prepping cases and what not in order to load up some .40S&W. My 180gr FMJ bullets arrived last week so I got busy reading past threads on everyone's favorite powder for the .40... I ended up grabbing a pound of Unique to get started with.

Here is the issue... My reloading manual (Lyman 47th I believe) shows that a charge of 5.8gr of Unique is the MAX load for 180gr FMJ in 40 S&W. On the other hand, the data that came with my Lee die set shows 5.8gr as the MINIMUM load, and 6.4gr as the MAX. I checked out a few other websites and found that most of the suggestions also showed 5.8gr as the starting load and 6.4gr as the MAX.

So now I'm a bit confused. I know the Lyman guide may be a bit dated, but why the conflicting data?

BTW... I worked up a small batch of 180gr FMJ loads with 6.0-6.1gr of Unique and the shot fairly well.

 

[Scorch]

If you are using the exact same bullet, case, primer, seating depth and the same firearm that Lyman used, that may very well be max. Apparently it was in their test gun. On the other hand, the other sources got their data by using different components in different firearms. However, when I check in my Lyman manual, it shows the 180 gr Sierra on top of 5.6 gr of Unique as being MAX in a pistol, 5.8 gr of Unique is MAX for a rifle.

 

[Bud Helms]

Just like some of the experienced hand loaders keep saying in this forum. The data is not conflicting unless you know the two manuals used exactly the same conditions to gather their data.

Barrel length, primer brand, type of firearm used (auto loader, revolver, test barrel), brass, sometimes the type of bullet used (cast, hardcast, jacketed), temperature, humidity ... phase of the moon.

If you are going straight to the max end, you haven't read your manual. If you have read your manual then you're working upward in safe fashion. Right? Then max load for your gun is wherever you find it to be. I get above the half way point in the load range, I get real cautious, unless I've been there before.

I have taken data from various manuals and compared the load ranges. You can come up with a wider or a narrower range than either manual gives you, but it has no validity if the conditions of test were deifferent.

 

[SL1]

Sixer

Was the Lyman manual data for a lead bullet, by any chance?

SL1

 

[jepp2]

Data for Unique from the Reloading Manual for the 40 S&W:

Sierra data, Para Ordnance P-16 5" BBL 4.6 - 6.3 gr (800 - 1050 FPS)
OAL 1.125"

Speer data, S&W 4006 4" BBL 6.0 - 6.7 gr (849 - 1000 FPS) OAL 1.120"

Alliant data, no pistol specified, 6.4 gr max load 1010 FPS, no starting load given
OAL 1.125"

So your trial was in the right ballpark. Watch OAL and check for setback!! I measure the first in the magazine, load a second, then fire the first (last in the mag). Then I remove the live round from the chamber and measure to determine setback.

 

[Sixer]

Then max load for your gun is wherever you find it to be.

Sorry to sound like a noob ( even though I am ).... but how exactly do I know when I've reached MY max load? Other than blowing up my gun of course

 

[QBall45]

Signs of too much pressure include several things...

Flattened primer
Cratered/flowing primer
Case head seperation
Cracked/split case body
Deformed case

Ya forgot to mention which firearm you are loading this 40s&w for.

 

[SQUAREKNOT]

If you are using powder dump be advised that in that range my Redding has a
0.9 gr range in throws. Unique doesn't meter well at all for me. I'm going to buy the smaller chamber and try again.

 

[wncchester]

"So now I'm a bit confused. I know the Lyman guide may be a bit dated, but why the conflicting data?"

Different guns.


"Then max load for your gun is wherever you find it to be. ... how exactly do I know when I've reached MY max load?"

You don't and you can't. Listen to the books for a max charge, ESPECIALLY so for noobs. The rest of us can't tell a lot more that you can. Witness:

"Signs of too much pressure include several things...

Flattened primer
Cratered/flowing primer
Case head seperation
Cracked/split case body
Deformed case"

!!!! Those are pressure signs for RIFLES, indicating pressures in the 60-70 psi range! Any handgun made will come from together long before you see ANY of those "pressure signs!" (And cracked/split case bodies are from loading/firing a case too many times, not too much pressure.) Pistol shooters just don't have much to go on, so listen to the books - even if/when they contridict.

Obtaining a "max" handgun load is nearly pointless for effect and really beats up your pistol for nothing.

 

[Sixer]

Ya forgot to mention which firearm you are loading this 40s&w for.

Whoops. Glock 23 with a Storm Lake barrel

If you are using powder dump be advised that in that range my Redding has a 0.9 gr range in throws. Unique doesn't meter well at all for me. I'm going to buy the smaller chamber and try again.

No doubt! I am using a Lee Auto powder measure and am getting loads from 5.7gr and 6.4gr. It's seriously frustrating. I decided to go with Unique from what others had to say about it here on the boards. Actually, it wasn't my first choice, but it was in the top 3 and all that my reloading shop had. It would be nice to have something that meters consistently though.

As far as finding my own MAX load goes. I'm just plinking... not trying to push any limits here. Don't have a chrono yet, and don't feel the need to keep working up to a load that goes kaboom

 

[BigJimP]

0.7 gr total variation - is a lot ....... be careful man ....

I'd recommend you do something to get your variation down a little more ( and if your max is 6.4 and min is 5.8 ) dump and remeasure anything at 6.4 or more and anything at 5.8 or below / with a goal of 6.0 - 6.2 as an example. Even that spread of 0.2 gr is more than I would like personally / but at least its in the middle of the range.

 

[Sixer]

0.7 gr total variation - is a lot ....... be careful man ....

Definitely good advice BigJim.

I have been checking the powder in EACH case after it has been charged. It's a PITA and really slows the process down, BUT I do enjoy my fingers and would prefer to keep them all in tact, so it's worth checking and double checking.

I have noticed that when the hopper is about 1/3 of the way full of powder I am getting more consistent throws ( right at 6.0 gr ). However, when I start to get a bit low on powder, the charges seem to vary more.

It got me wondering if maybe the weight on top of the powder ( or lack thereof ) was affecting the consistency? I have thought about using a light circular piece of wood, or small lid of some type to place on top of the powder inside the hopper to keep a little weight on the powder when it gets lower. It's just an idea, may not work at all, but I doubt it will hurt much as the variation is already pretty bad...

 

[BigJimP]

Depth of powder in the cannister can affect the way it drops / but typically it gets worse as the powder volume gets lower ..... so I never let my powder measures get below half full.

Just thinking out loud .....( I don't use the Lee system) but have you thought about adding some weight to your bench, maybe bolting everything down tighter - to make sure there is no flex in your bench, that might be causing this variation .....

one trick is to get someone to stand a few feet away from the powder measure / watch you make some powder drops ( if anything vibrates or moves at all ) then you need a more stable platform. Its easier to see, if you're standing back vs on top of the measure using it..

 

[SL1]

You probably need a baffle or two

See Unclenicks files ( http://drop.io/unclenick )for designs of baffles that you can cut out of some flat material. The file explains how to insert them and how they help.

Basically, they do the OPPOSITE of what you are thinking about. Instead of ADDING weight to the powder column in the measure, they REDUCE THE WEIGHT AT THE BOTTOM where the measurement is made and KEEP IT RELATIVELY CONSTANT. So, you were basically onto the right concept, but using a method that probably won't work as well as a baffle (or two).

SL1

 

[Sixer]

BigJim, my reloading table is pretty sturdy and most other powders don't vary like that. However, it's definitely something I will consider and check.

SL1, thanks for the link. I can't get it to open on my work computer but I will check it out later. Appreciate it!