confusing 9mm load data?

[parrothead600]

I am still a novice when it comes to reloading, so I like to double-check everything & not "blindly" follow instructions without understanding what & why I am being told to do it. I am looking at Lyman's Cast Bullet Handbook 4th Edition (pg 247). For those without the book, it refers to 9mm Luger.
The boolit that I am using is the Lee #356-102-1R with Unique powder. This manual states a starting load of 5.7gr., which seems like quite a bit of charge. There is not very much space left in this case to seat the boolit. If you look at their data for a 90gr lyman boolit, the starting load is 5.0gr of Unique. If you look on the next page, the starting loads range from 3.2 - 4.4gr of Unique(120 -147gr boolits).
I did load 5 cartridges w/ 5.7gr. They cycled fine w/ no evidence of too much pressure. Then I loaded 20 cartridges w/ 5.0gr. They also cycled fine.
Is it going to be a problem with going below the suggested starting grains? Does the suggested starting grains of 5.7 seem excessive? Also, the maximum load grains listed for this powder/boolit is 6.3gr:shock:, which I'm not sure if it could be done without compressing the powder. Sorry to be long-winded; I just want to understand the data & above all,BE SAFE.
Thanks in advance...

[buckwheatpaul]

The problem with too low, below min. charge, is the chance of a stuck bullet in the barrel. I consult several manuals when working up loads and start low and work up....congrats on admitting double-checking everthing and not blindly following instructions.....as you grow you will get a good feel for what works best but never never never give up checking your work.....Paul

[KenH]

I'll let the experts in the group give the final comment, but I will say I do agree with you your info is confusing. The 102 grain bullet should have a lower min powder charge than the 90 grain for sure. Using the Lee 356-102 cast bullet I tend to load around 4.2 grains of Unique (1.02" OAL) for solid cycling with my Glock 43. Not a heavy load by any means, but a pleasant plinking load that punches holes in paper just fine. The cartridge OAL is pretty sensitive with 9mm since it's such a small case.

Ken H>

[rintinglen]

One of the things to look at closely in the 9 mm Luger Cartridge is the OAL. Unlike some of the old revolver cartridges that were originally designed for Black powder shooting, the 9mm has a very finite firing chamber and is designed to run at a fairly high pressure. a modest reduction in length that might be negligible in a 44 special can have a significant impact on pressure. However, in this case that is not what has happened.
The Data for the 358-242 90 grain boolit starts at 19,900 cup. That for the Lee boolit starts at 27,700 psi. The Lee starting loads all seem to me to start pretty high, while the Lyman loads seem very low--like to the point of not functioning in some guns. My RCBS number 1 Cast Bullet Manual shows a 90 grain boolit starting load for Unique as 6.1 grains.

What's a fellow to Do? I would use the data from the Lyman Number 4 manual, since it is for the exact boolit You are using, I would use the start load and if it worked reliable and was adequately accurate, I would blithely go on my way and shoot as many of those little boogers as I could make and load until it stopped being fun or I got another mold. I personally have used 5.5 grains of Unique with the 90 grain 358-242 (Which casts about 93 grains from wheel weight alloy, at least in my sample) but have since gone on to using the heavier 358-242 120 grain and the Lee 356-120 TC.

[MT Gianni]

How do the bullet bearing surfaces compare?

[runfiverun]

and how much case capacity are they using.
just because a weight difference is present the shape will over ride the difference.
the 90gr boolit could use more [precious] case capacity when seated to the specified oal's.

[parrothead600]

Thanks to all that responded. Lots of good information to consider.

[Ed_Shot]

The Lyman 4th Ed HB is my primary guide. I have the Lee 356-102-1R I don't have any 9MM chrony data for it. The Lyman 356242 (mine drops at 92.5 gr) is my primary .380 boolit but I have loaded and chrony'd it in 9MM. My 356242 (92.5 gr) at the COAL of 1.060 (instead of the specified 1.045) using the Lyman HB starting load of Red Dot 4.1 gr. gave an average velocity of 1325 fps in my CZ 75B and 1340 fps in my G22 with conversion barrel. This is @ 200 fps faster than Lyman lists. At the time I pulled some loaded rounds to confirm I had the load right. My notes say "some primer cratering". Anyway I have settled on a load of Red Dot 3.6 gr which gives good accuracy and function at 1160 fps. Just my experience.