Conflicting load data for XDM 40

[wyofool]

A friend gave me some 40SW 180gr TMJ FN so I thought this would be a good time to test load each of my five pistol powders. I found all five in my “One Book/One Caliber” for 10mm/.40S&W LoadBook in the section for Speer Bullets. They list three styles GDHP SB, TMJ FN, and GDHP. Using their data I loaded 10 of each powder with a mid-load as follows:
700-X 5.2gr their start 5.0 max 5.5
Unique 6.3gr their start 6.0 max 6.7
AA No5 7.3gr their start 7.0 max 7.8
Bullseye 5.1gr their start 4.9 max 5.5
TiteGroup 4.2gr their start 4.0 max 4.7

While cleaning up after loading I was looking in the Lyman load data and they have Bullseye at 4.9 to 5.6 and Unique also at 4.9 to 5.6. for a 180gr Jacketed HP??? WTH.

Looked up Sierra Bullets in the LoadBook 180gr JHP Unique 4.6 to 6.3 and AA No5 6.3 to7.5.

Same book Hornady Bullets 180gr HP-XTP, HAP, and FMJ-FP ENC AA No5 5.7 to 7.2

Went to the powder websites' load data:
Hodgdon shows 700-X for the XTP 4.3 to 4.7 Titegroup 4.2 to 4.7

Alliant shows Unique at 6.7 max and Bullseye 5.5 max

Accurate shows AA No5 with Hornady XTP 5.9 to 6.6, a Berry HP 5.7 to 6.7 and Sierra FPJ 6.0 to 6.7
What to make of this?? The 700-X and the AA No 5 are loaded too high.
Now what?

[HangFireW8]

Not to be rude, but that "one caliber" book covers 2 cartridges, did you double check that you're not using 10mm loads?

[wyofool]

Not to be rude, but that "one caliber" book covers 2 cartridges, did you double check that you're not using 10mm loads?

I double checked and am using the .40 S&W loads

[Hickory]

There are so many different things that will cause load variances from different loading manuals. A few examples.

1) Difference in chamber size and type of firearm.
2) Lots of the same powder will and can have a slightly different burn rate.
3) Lots of the same powder can have slightly different pressure spikes.
4) The bore on the test firearm may vary in bore & groove diameter and the smoothness or roughness of the bore & grooves.
5) The primers can vary from lot to lot affecting pressure and velocities.

It is ALWAYS a good idea to work up a load when ever any component has changed, especially when loading maximum velocities & pressure.

[dragon813gt]

First you should always use the starting load and work up. You should also compare loads from different manuals before deciding on one. The “one caliber” books are reprinted data and it’s older and out of date in some cases.

You cannot use XTP data for any other bullet. Same goes for using JHP loads for XTPs. XTPs have a different bearing surface and the loads are not interchangeable w/ other bullets.

I say all this w/ the caveat that no load in a manual will give the same velocity/pressure in your gun. So some judgement must be used when working up loads. This is why comparing multiple sources is important.

[Silver Jack Hammer]

Check your COL, that’ll really affect pressures especially in a high pressure cartridge like the 40. The Speer manual has a notice that their data is only for the combination of bullets which they tested. If a bullet manufacturer has a canular and you seat according to the canular, you may be seating to a different COL that a previous bullet from a different manufacturer you had success with.

Loading manuals do vary, I tend to stick to the most recent manual from my favorite company but I begin with a starting weight of powder and work up. I use a chronograph and keep notes.

The Speer manual is real good especially when you are loading Speer bullets.

Another thing I tend to do is stick with one brand of powder. Most powder companies have many different powders with different rates of burn to choose from to meet all our needs. Sticking with one company tends to make me familiar with those powders.

And of course if you pour your own boolits you’ll know your COL with your boolits all the time.

[Tackleberry41]

The likely issue is the 2 books using different bullets. 180gr is not the same as 180gr. Lyman has different data for 2 250gr cast bullets in 45 colt. Different designs one is shorter than the other. So changes things internally.