.380 auto OAL question

[Cliff6]

I have been shooting a Sig P238 using Berry's 100 grain round nose bullets and 2.8 gr W238 with no issues and an OAL of 0.975. "Most" loads indicate an OAL of 0.980, but to plunk and twist, I need 0.975. No problem.

I recently purchased 1,000 99 grain J-Ames CRB coated lead bullets. In order to pass plunk and twist, they have to be loaded at 0.925". The bullet is quite a bit different shape and I have attached a photo of the test round. I know this is the OAL needed for this gun, but with the change in OAL, I'm wondering about the powder charge. 50 thousands difference.

I've been using W231 at 2.8 grains. Hodgdons shows a 95 gr ACME RN at 3.0 to 3.8 gr and an OAL of 0.970.

The J-Ames bullet seats to the mark on the case, the Berry's round nose seats about half that far. Neither causes a compressed load.

Thoughts?

 

[Dudedog]

Not a lot of wiggle room in .380 with W231. (you said W238 but I think you meant W231/HP38)
Just guessing but I would put the MAX around 3.1 or 3.2. Maybe a hair more.
You have a shorter OAL and a ~5% heavier bullet than the Acme so I would stay well south of 3.8. (of course I am chicken, but I still have all my fingers)
If they were mine I would back off to about 2.6 and work up carefully .1 at a time from there until I got good function.

You didn't say the planned use but if for the range I see no reason to push.
If you want more vel than W231 can give you CFE-P has worked well for me in .380 for MAX loads.

 

[reloaded_in_pa]

I use a 102g rn with 2.7 w231 and my oal is 0.925 to plunk correctly. That pushes at 780-790 fps.
As Dudedog said, back off a bit and work back up.

 

[WeekendReloader]

Measure the length of your Berry's bullet and the new J-Ames bullet. Then do the math to see the difference in seating depth. I bet it isn't 0.050" (I bet it is half that amount). It sounds like the J-Ames bullet carries more weight in front with a fatter ogive.
If the seating depth is the same, you can use a similar powder charge. If the seating depth is greater (meaning it seats deeper into the case), I would back off the powder charge a few tenths and load a few test rounds.

 

[Dudedog]

From the above pic it looks like the J-Ames bullet is quite a bit deeper in the case than the Berrys the way the OP is loading them.

 

[Cliff6]

Not a lot of wiggle room in .380 with W231. (you said W238 but I think you meant W231/HP38)
Just guessing but I would put the MAX around 3.1 or 3.2. Maybe a hair more.
You have a shorter OAL and a ~5% heavier bullet than the Acme so I would stay well south of 3.8. (of course I am chicken, but I still have all my fingers)
If they were mine I would back off to about 2.6 and work up carefully .1 at a time from there until I got good function.

You didn't say the planned use but if for the range I see no reason to push.
If you want more vel than W231 can give you CFE-P has worked well for me in .380 for MAX loads.

I would appreciate that. CFE Pistol is what I am wanting to load, but I'll cut it back some. I just want light target practice loads.

 

[Cliff6]

I use a 102g rn with 2.7 w231 and my oal is 0.925 to plunk correctly. That pushes at 780-790 fps.
As Dudedog said, back off a bit and work back up.

Ok, thanks. I've been loading 2.8 W231.

 

[Cliff6]

Measure the length of your Berry's bullet and the new J-Ames bullet. Then do the math to see the difference in seating depth. I bet it isn't 0.050" (I bet it is half that amount). It sounds like the J-Ames bullet carries more weight in front with a fatter ogive.
If the seating depth is the same, you can use a similar powder charge. If the seating depth is greater (meaning it seats deeper into the case), I would back off the powder charge a few tenths and load a few test rounds.

I can certainly see your point. I have been loading 2.8 gr of W231 and the starting load for the nearest round I can find is 3.0....so I think I should be okay.

 

[Soonerpesek]

If the seating depth is the same, you can use a similar powder charge

I agree with @WeekendReloader ,It appears that the case capacity when both bullets are seated, is very similar.

The flat nosed bullet itself appears to be shorter than the RN..( about.050" maybe ??)

 

[Cliff6]

I agree with @WeekendReloader ,It appears that the case capacity when both bullets are seated, is very similar.

The flat nosed bullet itself appears to be shorter than the RN..( about.050" maybe ??)

Ok, thanks everyone. I must have just had a brain fart there.
Berry's round OAL 0.972
bullet 0.467
case space 0.505

J-Ames round OAL 0.936
bullet 0.435
case space 0.501

Close enough to be insignificant. Sometimes the brain just slips out of gear

 

[1KPerDay]

3.1 W231 is max or over max in some manuals IIRC. I’d start well below 3.0 if i had to seat that deep.

 

[Strainer]

I have loaded 380 auto using the Berry’s 100 gr RNHB plated #12535, bullet length measures .470”; seated to Berry’s recommended COL of .970”.
Powder 2.7 gr Win231.

I subsequently switched to X-Treme 100 gr RNFP plated bullets, bullet length measures .432”; seated to a COL of .950” that I came up with.
Powder 2.7gr Win 231.

Works for me in S&W Bodyguard 380.
Hopefully a useful comparison for you.

From your subsequent post I see you need a COL of .936, and your bullet is lead. Given that bullet if it were me I might start with a slight reduction in powder charge from what I was using above, say maybe 2.6gr.
All usual disclaimers apply, use at your own risk, consult reloading manuals, etc.
Good luck and stay safe!