.380 load data: 100 grain lead w/ IMR PB

[9thchild]

Hey guys, I found some data for 100 grain jacketed bullets w/ this powder, but can't seem to find any for the same weight in a lead bullet.

Is there some kind of simple equation I can use or a general rule for using lead vs jacketed w/ the same powder? Does the distinction b/w bullet composition even matter if it is the same weight?

I am kind of a noob if you can't tell...

 

[jim243]

Start at the min load data for jacketed bullets and work your way up 0.2 of a grain at a time while checking for pressure signs. Remember keep lead bullets below 1,100 FPS unless using gas checks with them.

Jim

 

[ArchAngelCD]

Yes, the data for lead bullets is usually lighter than for jacketed bullets and should not be mixed. (as you guessed)

The definitive source for lead bullet data today is the Lyman Cast Handbook 4th Edition but unfortunately while they have plenty of load data for the 380 Auto and a 102gr lead bullet they do not list PB.

They do however list PB with a 120gr Lyman #356242 bullet if it helps.
PB 1.7gr 620 fps 10,800 CUP
PB 2.2gr 750 fps 15,800 CUP

Sorry I couldn't have been more help.

 

[9thchild]

Thank you, both of your responses shed some light on how to approach this.

The problem with your approach Jim, is that the data I do have only lists the maximum load, with no starting load. That max load is 2.8 grains. I think what I may do is start with the 1.7 grains that Lyman lists for the 120 grain bullet (which is quite a chunk of lead coming out of a .380!).

As far as minimum OAL, there should be no difference between lead/jacketed as far as that is concerned, correct?

 

[TfflHndn]

If you go down that far, you may risk problems. Generally, a heavier bullet will take a lower charge because pressure builds faster behind it as it takes more to get it moving than with a lighter bullet. Your minimum load with the jacketed bullet would be about 10% below the max load, putting you at about 2.5 grains of PB. Your 1.7 grain load would be 40% below the max load, albeit for jacketed. I think that's too much of a reduction. I'd go with Jim's advice and start at 2.4-2.5, especially if you have a chrony and can see what velocity you are getting right away. For an extra measure of safety, you could go to 2.2 and watch for signs of underpressure.

 

[ArchAngelCD]

9thchild,
My rule on OAL in semi-auto pistols is to load as long as I can and still pass the plunk test. Of course I don't load longer than SAAMI specs but I do try to load to the pistol.

Lyman lists OAL's of:
.980" w/90gr Lyman #356242 mold
.960" w/Lee #356-102-1R mold
.980" w/120gr Lyman #356242 mold

 

[9thchild]

I think I understand. So because the heavier bullet actually takes less powder, going down to 1.7 for the lighter bullet would make no sense. Unfortunately I don't have a chronometer, but I will start around the 2.2-2.3 range and watch for signs of underpressure.

Eventually, once I get these made and tested I will dig up this thread and post my thoughts. Out of curiosity how much does a basic chrony run?

 

[ArchAngelCD]

IMO and only my opinion, if you use the 120gr load max charge of 2.2gr you will be safe because the 120gr bullet is so much heavier than a 100gr bullet. (by 20%) I would think in such a small case though, maybe an additional .1gr or 2.gr is as high as I would go without a chrono to test velocities. It's also possible the 2.2gr charge load will be very accurate and you won't need to go further.

Don't forget the range report...

 

[9thchild]

Thanks Arch. I agree that 2.2 seems like the best way to start.

It may take a while as I don't get to shoot much and my preferred range is 45 minutes away, but I will post my results.

 

[9thchild]

Updates

So last night I sat down and experimented a little. Turns out the little dipper included in the Lee .380 dies is exactly 2.5 grains so I settled on that as a starting point. To be accurate, the charge is probably somewhere between 2.4 and 2.5 but not exceeding the latter.

It should be noted that the weapon I am loading for is a Taurus TCP, which leads us to a new and unforeseen complication. The first round I loaded measured out at .982.5", which is right in the middle of the minimum and maximum suggested in the Lee manual for IMR PB. The problem is that this round would not feed properly in the TCP. After some further experimentation and crimp adjustment, I found I could get them to feed in the .960" range.

Is this round even safe to fire? Is there a way to adjust crimp to get the rounds to feed properly at the appropriate length? Should I instead reduce the charge according the reduction in OAL?

 

[9thchild]

The only solution I can come up with is to trim the cases so that I can seat the bullets deeper. That still won't work, as seating the bullet deeper could also lead to unsafe pressures. I think it is time to abandon this project.

 

[ArchAngelCD]

The first round I loaded measured out at .982.5", which is right in the middle of the minimum and maximum suggested in the Lee manual for IMR PB. The problem is that this round would not feed properly in the TCP. After some further experimentation and crimp adjustment, I found I could get them to feed in the .960" range.

Is this round even safe to fire? Is there a way to adjust crimp to get the rounds to feed properly at the appropriate length? Should I instead reduce the charge according the reduction in OAL?

The OAL in the manual is not for PB but the bullet they used. Unless you are using the same exact brass, trimmed to the same exact length and you use the same exact bullet they used the OAL listed is useless to you. Anyone who loads for a semi-auto has to adjust the COLA for the handgun they are shooting. If you pistol shoots correctly with a COLA of .960" that's what you should use.

The only solution I can come up with is to trim the cases so that I can seat the bullets deeper. That still won't work, as seating the bullet deeper could also lead to unsafe pressures. I think it is time to abandon this project.

Trimming the brass or seating the bullet deeper will result in the same condition, less case capacity. Both will increase pressure. I always suggest starting low and working up because there are so many variables.

 

[9thchild]

Thanks Arch. I think I will reduce the charge a bit, and use the OAL needed to feed in my firearm. OAL is probably the most confusing thing about reloading so far, especially when you are tweaking published data to suit your components.