Lyman's 49th Edition?

[Steven57]

Factory makes 90gr and 100gr for the 9mm. The ones I have are Frangible. Good for practice, varmints, light loading.

 

[Kuyong_Chuin]

I interchange load data for 124 and 125 gr bullet weight if they are the same bullet nose type (FMJ for FMJ, JHP for JHP, etc.).

Okay now I am confused too. When looking at my load data for the 9MM there is a big difference in data from the 124 grain jacketed bullet and the 125 grain jacketed bullet. Example: ACCUR#7 124 grain jacketed bullet starts at 6.9 grains and max at 7.9 grains, same powder using the 125 grain jacketed bullet shows a starting load of 5.7 grains and a max of 6.5 grains. So if you used the 124 grain data on a 125 grain bullet you would have a starting load 0.4 grains over the max for the 125 grain bullet. It was like that for every powder I checked that was listed for both bullets. Why is there such a wide gap difference in powder charge between bullets that are 1 grain apart?

 

[NeuseRvrRat]

Okay now I am confused too. When looking at my load data for the 9MM there is a big difference in data from the 124 grain jacketed bullet and the 125 grain jacketed bullet. Example: ACCUR#7 124 grain jacketed bullet starts at 6.9 grains and max at 7.9 grains, same powder using the 125 grain jacketed bullet shows a starting load of 5.7 grains and a max of 6.5 grains. So if you used the 124 grain data on a 125 grain bullet you would have a starting load 0.4 grains over the max for the 125 grain bullet. It was like that for every powder I checked that was listed for both bullets. Why is there such a wide gap difference in powder charge between bullets that are 1 grain apart?

were you looking at two different manuals? there are more variables at play than what type of bullet and powder they used. there are test barrel differences, OAL differences, and, most importantly, different lawyers.

 

[Steven57]

Use the heavier data for the lighter bullet. Not the other way around.

 

[Kuyong_Chuin]

were you looking at two different manuals? there are more variables at play than what type of bullet and powder they used. there are test barrel differences, OAL differences, and, most importantly, different lawyers.

Nope looking at the Lee 2nd Ed.

 

[Sport45]

Why is there such a wide gap difference in powder charge between bullets that are 1 grain apart?

Maybe a different seating depth. Was one a JHP and the other a FMJ?

 

[Kuyong_Chuin]

Use the heavier data for the lighter bullet. Not the other way around.

Wouldn't work the other way around ether because the max for the heavier round is 0.4 grains under the starting load for the lighter round.

 

[Kuyong_Chuin]

Maybe a different seating depth. Was one a JHP and the other a FMJ?

Both rounds listed was for Jacketed data. Okay there is a difference in the minimum O.A.L for the two rounds. The lighter bullet has a min. O.A.L. of 1.145 and the heavier bullet' s Min. O.A.L. is 1.035

 

[NeuseRvrRat]

Nope looking at the Lee 2nd Ed.

there's your problem. you really were looking at two different manuals, you just didn't know it. Lee doesn't do any ballistic testing of their own. all they do is copy data from other manuals and compile it in theirs.

 

[mgmorden]

Nope looking at the Lee 2nd Ed.

As stated by another poster all Lee does is compile data from other sources, but check the OAL - there's a decent change they're different. Different OAL's (even with the same exact bullet) will yield a different start/max powder charge.

 

[Kuyong_Chuin]

As stated by another poster all Lee does is compile data from other sources, but check the OAL - there's a decent change they're different. Different OAL's (even with the same exact bullet) will yield a different start/max powder charge.

Yea, I found that out when mentioned by a few of the other posters. I did not think to check the O.A.L. when I first compared the two rounds load data.